WO2000003024A2

WO2000003024A2 - Alleles of the human mu opioid receptor, diagnostic methods using said alleles, and methods of treatment based thereon

Info

Publication number: WO2000003024A2
Application number: PCT/US1999/015707
Authority: WO
Inventors: Mary Jeanne Kreek; Karl Steven Laforge; Lei Yu; Jay A. Tischfield
Original assignee: The Rockefeller University; The Advanced Research And Technology Institute
Priority date: 1998-07-10
Filing date: 1999-07-10
Publication date: 2000-01-20
Also published as: WO2000003024A3; WO2000003024A9

Abstract

Provided herein are variant alleles of a gene encoding a mu opioid receptor, along with cloning vectors for replicating such variant alleles, expressing vectors for expressing the variant alleles to produce variant mu opioid receptors, and antibodies to such variant receptors. Also disclosed are binding characteristics of such variant receptors regarding binding to opioid ligands, and the using of such binding characteristics to diagnose subjects susceptibility to pain, susceptibility to an addictive disease, selecting an appropriate pain reliever along with a therapeutically effective amount of the reliever to administer to a subject suffering from pain. In addition, diagnostic methods for diagnosing a disease or disorder such as infertility, constipation, diarrhea immune response relative to a standard, and decreased ability to withstand stress relative to a standard, along with commercial kits for diagnosing such diseases or disorders. Furthermore, the invention is also directed to identification of targeted prevention methods, early therapeutic intervention, and improved treatment of opioid addiction, infertility, constipation, diarrhea, impaired immune responsiveness, and stress.

Description

ALLELES OF THE HUMAN MU OPIOID RECEPTOR, DIAGNOSTIC METHODS USING SAID ALLELES, AND METHODS OF TREATMENT BASED THEREON

GOVERNMENTAL SUPPORT This invention was made government support under Grant Nos. NIDA R01-DA09444,

NIDA P50-DA05130, and NIDA K05-DA00049 awarded by the National Institute of Drug Addiction. The Government has certain rights in the invention.

FIELD OF THE INVENTION

This invention relates generally to alleles of the human mu opioid receptor gene, along with products derived from such alleles. Also included herein are methods of diagnosing various susceptibilities using such alleles and determining treatment for certain diseases based upon the presence of specific alleles of the human mu opioid receptor gene, and various diseases or disorders related to physiological functions regulated by the hypothalamus pituitary adrenal axis (HPA) or the hypothalamus pituitary gonadal axis (HPG).

BACKGROUND OF THE INVENTION Opioid drugs have various effects on perception of pain, consciousness, motor control, mood, autonomic function, and can also induce physical dependence. The endogenous opioid system plays an important role in modulating endocrine, cardiovascular, respiratory, gastrointestinal functions, and immune functions. Opioids, either exogenous or endogenous, exert their actions by binding to specific membrane-associated receptors.

Examples of exogenous opioids presently known include, opium, heroin, morphine, codeine, fentanyl, and methadone, to name only a few. Moreover, a family of over 20 endogenous opioid peptides has been identified, wherein the members possess common structural features, including a positive charge juxtaposed with an aromatic ring that is required for interaction with an opioid receptor It has been determined that most, if not all the endogenous opioid peptides are derived from the proteolytic processing of three precursor proteins, 1 e , pro-opiomelanocortm, proenkephahn, and prodynorphin In addition, a fourth class of endogenous opioids, the endorphms, has been identified (the gene encoding these proteins has not yet been cloned) In the processing of the endogenous opioid precursor proteins, initial cleavages are made by membrane-bound proteases that cut next to pairs of positively charged amino acid residues, and then trimming reactions produce the final endogenous opioids secreted from cells in vivo Different cell types contain different "processing enzymes so that, for example proopiomelanocortm can be processed into different endogenous peptides by different cells For example, in the anterior lobe of the pituitary gland, only corticotropin (ACTH), β-hpotropin, and β-endorphin are produced Both pro-enkepha n and pro-dynorphin are similarly processed by specific enzymes in specific cells to yield multiple opioid peptides

Pharmacological studies have suggested there are numerous classes of opioid receptors which bind to exogenous and endogenous opioids These classes differ in their affinity for various opioid ligands and in their cellular and organ distribution Moreover, although the different classes are believed to serve different physiological functions, there is substantial overlap of function, as well as of distribution

In particular, there are at least three known types of opioid receptors, mu (μ), delta (δ), and kappa (K), to which morphine, the enkephahns, and the dynorphins can bind These three opioid receptor types are the sites of action of opioid ligands producing analgesic effects However, the type of pain inhibited and the secondary functions vary with each receptor type The mu receptor is generally regarded as primarily associated with pain relief, and drug or other chemical dependence, I e , addiction and alcoholism

The human mu opioid receptor, which modulates corticotropin releasing hormone, has been isolated and described in PCT Application WO 95/07983 (March 23, 1995) (SEQ ID NO. l) as well as in Chen, Y , Mestek, A , Hurley, J A , & Yu, L (1993) Mol Pharmacol 44, 8-12, and Wang, et al , FEBS letters, (1994)338 217-222 Furthermore, SEQ ID NO 1 can readily be obtained in GENBANK under accession number L25119 The cDNA therefor contains an open reading frame capable of encoding a protein of 400 amino acid residues with 94 % sequence similarity to the rat mu opioid receptor Hydropathy analysis of the deduced protein indicates the presence of seven hydrophobic domains, typical of G-protem-coupled receptors The N-terminus contains five potential N-1 inked glycosylation sites which remain conserved between the human and the rat mu opioid receptor A variant in which Asn-40 is changed to Asp (N40D) is reported in GENBANK Accession No U 12569

In the body and brain, heroin is hydrolyzed to morphine, which acts at the mu opioid receptor and results in an euphoric effect and confers the reinforcing properties of the drug and contributes to development of addiction Heroin addiction can be managed through treatment, primarily methadone maintenance However, the biological basis of heroin addiction may include diversity of gene structure Such genetic diversity of the human mu opioid receptor, and the impact of such diversity on receptor function, could contribute to the success or failure of pharmacological management Similar problems with respect to patient response to pharmacological treatment could occur in most, if not all addictive diseases, such as heroin addiction, alcohol addiction, or cocaine addiction to name only a few, or a combination thereof

Moreover, addiction to opioid drugs, especially heroin is a major social problem in the United States, and throughout the world For example, recent epidemiological assessments sponsored by the NIH-NIDA and other federal agencies have found that around 2 7 million persons in the United States have used heroin at some time Moreover, the numbers of "hardcore" long-term heroin addicts (addiction being defined herein as self administration of a regular, multiple, daily dose use of a short-acting opioid, such as heroin, for one year or more, with the development of tolerance, physical dependence and drug-seeking behavior, a definition codified in the Federal guidelines governing pharmacotherapy using long-acting agents such as methadone or LA AM, and used as the minimal requirement for entry into treatment) are now estimated to be approximately one million persons In addition, it has been estimated that around 24 million persons in the United States have used cocaine for some time, and of that number, approximately one million use cocaine regularly, and at least 600,000-700,000 are cocaine addicts In view of the importance of the human mu opioid receptor in the study of addiction, and the epidemic proportions of drug addiction, especially to heroin, alcohol or cocaine, or a combination thereof, in the United States and throughout the world, and its involvement in the neuroendocπne system, and physiological functions regulated thereby, efforts have been made to investigate whether any polymorphisms in the gene encoding the human mu opioid receptor exist in the population, and whether such polymorphisms result in a phenotype that has an increased or decreased susceptibility towards development of addiction to exogenous opioids, such as heroin, or alcohol, cocaine, or other addictive drugs For example, in an article entitled Human mu opioid receptor gene polymorphisms and vulnerability to substance abuse (Berrettim, W H , Hoehe, M R , Ferraro, T N , DeMaπa, P A , and Gottheil, E , Addiction Biology 2 303-308 (1997)), two polymorphisms in the human mu opioid receptor gene were reported One polymorphism (G to T) occurs at nucleotide 175 preceding initiation of translation, and a second coding polymorphism ^® to T) at nucleotide 229 (with respect to transcription initiation) on exon I results in an Ala to Val residue change However, data taken from a study indicated the C229T polymorphism does not differ in occurrence with statistical significance in addicts relative to non addicts (Id at 306) No functional studies were reported

It has been further determined that a receptor for both endogenous and exogenous opioids modulates the activity ot the hypothalamus pituitary adrenal axis (HPA) and the hypothalamus pituitary gonadal axis (HPG), which effects the neuroendocπne system and its production of signaling compounds that play important roles in regulation of numerous physiological functions In particular, the neuroendocπne system involves the integration of the neural and endocrine systems of the body, and is responsible for the coordination of numerous bodily functions An important part of this system is the hypothalamus, a specialized portion of the brain involved in receiving and relaying messages from the central nervous system to other parts of the body Upon stimulation by chemical signals from the central nervous system, the hypothalamus secretes hypothalamic hormones, such as corticotropin releasing factor (CRF) or hormone and gonadotropin releasing hormone or luteinizing hormone releasing hormone These factors in turn stimulate the anterior pituitary gland to secrete tropic hormones, or tropms, which are synthesized as relatively long polypeptides, and then are then biotransformed to produce active peptide hormones Pro-opiomelanocortin, which is processed into several active peptide hormones, including adrenocorticotropic hormone (ACTH), is an example of a tropic hormone ACTH stimulates the adrenal cortex to secrete additional hormones, like cortisol, a stress hormone humans which regulates glucose metabolism, and targets many tissues m the body In addition, examples of hormones produced by the anterior pituitary glad upon stimulation with gonadotropm releasing hormone include follicle-stimulating hormone and luteinizmg hormones These hormones stimulate the gonads, such as the ovaries and the testes, to secrete androgens, such as testosterone, progesterone, and estrogen, which in turn affect sexual development, sexual behavior, and other reproductive and nonreproductive functions As a result, the endogenous opioid system plays an important role in modulating endocrine, reproductive, cardiovascular, respiratory, gastrointestinal, immune functions, sexual development and function, as well as a person's response to stress

More specifically, in humans, it has been determined that chronic administration of opioids has an inhibitory effect on the HPA axis [McDonald et al , Effect of morphine and nalorphine on plasma hydrocortisone levels in man J Pharmacol Exp Ther 125 241247 ( 1959)] Basal levels of ACTH and cortisol are significantly disrupted in active heroin addicts suppression of ACTH and cortisol and abnormal diurnal rhythms of these hormones are found [Kreek, Medical safety and side effects of methadone in tolerant individuals JAMA 223 665-668 (1973)] Basal levels and the diurnal rhythm of ACTH and cortisol, which are disrupted in active heroin addicts, have been shown to become normalized in moderate to high dose, long-term methadone-maintained patients when compared to those of healthy volunteer subjects [Kreek 1973, Kreek et al , Orcadian rhythms and levels of beta-endorphin, ACTH, and cortisol during chronic methadone maintenance treatment in humans Life Sci 33 409-411 (1983), Kreek et al , Prolonged (24 hour) infusion of the opioid antagonist naloxone does not significantly alter plasma levels of cortisol and ACTH in humans Proceedings of the 7th International Congress on Endocrinology Elsevier Science pi 170, 1984]

In healthy volunteers, ACTH and cortisol levels decrease below the basal levels response to the infusion of β-endorphin indicating feedback of inhibition of pituitary ACTH release or suppression ot hypothalamic CRF release by β-endorphin [Taylor, et al , Beta-endorphin suppresses adrenocroticotropin and cortisol levels in normal human subjects J Clin Endocπnol Metab 57 592-596 (1983)], and also naloxone (an opioid antagonist) stimulates a rise in serum ACTH and cortisol, suggesting that the HPA axis is under the tonic inhibitory control of endogenous opioids normalized in steady-state chronic methadone- maintamed patients, their HPA axis responses to metyrapone-mduced stress appear to be no different from that of healthy volunteer subjects [Kreek, 1973, Kreek et al , Prolonged (24 hour) infusion of the opioid antagonist naloxone does not significantly alter plasma levels of cortisol and ACTH in humans Proceedings of the 7th International Congress on Endocrinology Elsevier Science pi 170, 1984]

Support for the effects of opioids on physiological functions regulated by the HPA and the HPG axes can be found in observations of heroin addicts More specifically, it has been observed that many heroin addicts are infertile, and in the case of female addicts, their menstrual cycle is dramatically disrupted to the point that they do not ovulate Furthermore, it has been observed that heroin addicts, and nonaddicted patients taking morphine, become constipated, and that the immune systems of addicts is weakened relative to the immune system of non addicts However once therapeutic agents designed to treat addiction, such as methadone, addicts become fertile, are no longer constipated, and have a immune system whose ability to fight foreign bodies is m parity with the immune system of a nonaddict

Hence what is needed is discovery of heretofore unknown polymorphisms of the human mu opioid receptor gene that can be used as genetic markers to map the locus of the human mu opioid receptor gene in the genome

What is also needed are the DNA sequences of heretofore unknown isolated nucleic acid molecules which encode human mu opioid receptors, wherein the DNA sequences include a combination of presently known and subsequently discovered polymorphisms of the human mu opioid receptors

Furthermore, what is needed is the characterization of the binding properties of heretofore unknown human mu opioid receptors produced from the expression of genes comprising such heretofore unknown polymorphisms of the human mu opioid receptor gene, or combinations of unknown polymorphisms and known polymorphisms Furthermore, what is needed is a characterization of the activity of such unknown human mu opioid receptors produced from the expression of nucleic acid molecules comprising such polymorphisms

What is also needed is a correlation between polymorphisms of the human mu opioid receptor gene, and the susceptibility of a subject to addictive diseases, such as herom addiction, cocaine addiction, or alcohol addiction, to name only a few

What is also needed are diagnostic methods to determine a subject's increased or decreased susceptibility to addictive diseases With the results of such methods, targeted prevention methods, early therapeutic intervention, and improved chronic treatment to opioid addiction can be developed Physicians armed with the results of such diagnostic methods can determine whether administration to a subject of opioid analgesics is appropriate or whether non-opioid derived analgesics should be administered to the subject Also, appropriate choice and type of analgesic can be made in treating a subject's pam

What is also need are methods of determining a subject's susceptibility to pain and responsibility to analgesics, and using that information when prescribing analgesics to the subject What is also needed is an ability to determine the binding affinity of the mu opioid receptor to endogenous opioids, such as β-endorphm, and the effect of this binding activity on the neuroendocπne system

The citation of any reference herein should not be construed as an admission that such reference is available as "Prior Art" to the instant application

SUMMARY OF THE INVENTION There is provided in accordance with the present invention, heretofore unknown polymorphisms of the human mu opioid receptor gene, and their use in mapping the locus of the human mu opioid receptor gene, determining susceptibility to addictive diseases. determining susceptibility to pain, and determining a therapeutically effective amount of pain reliever to administer to a subjeu suffering from pain, diagnosing a disease or disorder in a subject that is related to a physiological function regulated by the HPA or HPG axes of the neuroendocπne system, and selecting an appropπate therapeutic agent and a therapeuti- cally effective amount of such an agent to administer to a subject suffering from a disease or disorder related to a physiological function regulated by the HPA or HPG

Hence, the present invention extends to heretofore unknown polymorphisms of the human mu opioid receptor gene that can serve as genetic markers to map the locus of the human mu opioid receptor gene

The present invention further extends to DNA sequences of heretofore unknown isolated nucleic acid molecules which encode human mu opioid receptors, wherein the DNA sequences include a combination of presently known polymorphisms and polymorphisms of the human mu opioid receptors discovered by Applicants

The present invention further extends to the characterization of the binding properties of heretofore unknown human mu opioid receptors produced from the expression of isolated nucleic acid molecules comprising DNA sequences with such heretofore unknown polymorphisms of the human mu opioid receptor gene, or combinations of unknown polymorphisms and known polymorphisms

Furthermore, the present invention extends to characterizing the activity of such unknown human mu opioid receptors and particularly the increased or decreased ability of mu opioid receptors produced from isolated nucleic acid acids of the present invention to activate G protein-activated inwardly rectifying K⁺ (GIRK) channels via a G protem-mediated mechanism

The present invention further extends to Applicants' discovery that polymorphisms m an allele comprising a DNA sequence of SEQ ID NO 1 , such as Al 18G and C17T, which are described in further detail infra, are present in the population at a high frequency (greater than 5%)

Furthermore, the present invention extends to Applicant's discovery of a correlation between polymoφhisms of the human mu opioid receptor gene, and the increased or decreased susceptibility of a subject to addictive diseases, such as heroin addiction, cocaine addiction, or alcohol addiction, to name only a few The present invention further extends to diagnostic methods to determine a subject's increased or decreased susceptibility to addictive diseases With the results of such methods, targeted prevention methods, early therapeutic intervention, and improved chronic treatment to opioid addiction are set forth herein and encompassed by the present invention In addition, attending medical professionals armed with the results of such diagnostic methods can determine whether administration of opioid analgesics is appropπate or whether non-op 10 id derived analgesics should be administered to the subject Furthermore, appropriate choice and type of analgesic to treai a subject's pain can be made

Also, the present invention extends to methods of determining a subject's increased or decreased susceptibility to pam and response to analgesics, and the use of the information in prescribing analgesics to the subject

In addition, the present invention extends to methods of diagnosing a disease or disorder in a subject, wherein the disease or disorder is related to a physiological function regulated by the HPA or HPG axes of the neuroendocπne system Examples of such physiological functions include reproductive or sexual functions, gastrointestinal motihty, immune response, and ability to withstand stress

Broadly the present invention extends to an isolated vaπant allele of a human mu opioid receptor gene which can serve as a genetic marker, wherein the predominant or most common allele of a human mu opioid receptor gene found in the population comprises a DNA sequence of SEQ ID NO 1 , and a vaπant allele of the present invention comprises a DNA sequence having a variation in SEQ ID NO 1 , wherein the variation comprises G24A,

G779A, or G942A, or combinations thereof

Furthermore, the present invention extends to an isolated variant allele of a human mu opioid receptor gene as set forth above, which is detectably labeled Numerous detectable labels have applications in the present invention, such as radioactive elements, chemicals which fluoresces, or enzymes, to name onlv a few The present invention further extends to an isolated nucleic acid molecule hybridizable under standard hybridization conditions to an isolated variant allele of the human mu opioid receptor gene, wherein the predominant or "most common" allele of a human mu opioid receptor gene found m the population comprises a DNA sequence of SEQ ID NO 1 , and a variant allele of the present invention comprises a DNA sequence having a variation in SEQ ID NO 1 , wherein the variation comprises

G24A,

G779A, or

G942A. or combinations thereof

Moreover, the present invention extends to an isolated nucleic acid molecule hybridizable under standard hybridization conditions to an isolated variant allele of the human mu opioid receptor gene, wherein the predominant or 'most common ' allele of a human mu opioid receptor gene found in the population comprises a DNA sequence of SEQ ID NO 1 , and a variant allele ot the present invention comprises a DNA sequence having a variation in SEQ ID NO 1 , wherein the variation comprises G24A. G779A, or G942A, or combinations thereof, wherein the isolated nucleic acid molecule is detectably labeled Examples of detectable labels that have applications in this embodiment of the present invention are described above

In addition, the present invention extends to an isolated variant allele of a human mu opioid receptor gene, wherein the predominant or "most common" allele of the human mu opioid receptor gene encodes a human mu opioid receptor comprising an amino acid sequence of SEQ ID NO 2, and the variant allele of the human mu opioid receptor gene encodes a vaπant human mu opioid receptor comprising an ammo acid sequence having a variation in SEQ ID NO 2, wherein the variation comprises Arg260Hιs

Furthermore, the present invention extends to an isolated nucleic acid molecule hybridizable under standard hybridization conditions to an isolated variant allele of a human mu opioid receptor gene of the present invention, wherein the isolated nucleic acid molecule encodes a vaπant human mu opioid receptor comprising an amino acid sequence having a variation in SEQ ID NO 2, wherein the variation comprises Arg260Hιs

Namrally, the present invention extends to a vaπant human mu opioid receptor comprising an ammo acid sequence having a variation in SEQ ID NO 2, wherein the variation comprises Arg260Hιs

Furthermore, the present invention extends to an antibody having a variant human mu opioid receptor comprising an ammo acid sequence having a variation in SEQ ID NO:2, wherein the variation comprises Arg260Hιs as an lmmunogen Such an antibody can be a polyclonal antibody, a monoclonal antibody, or a chimeric antibody Moreover, an antibody of the present invention can be detectably labeled Examples of detectable labels which have applications in this embodiment comprises a radioactive element, a chemical which fluoresces. or an enzyme, to name only a few

In addition, the present invention extends to cloning vectors that can be used to clone copies of a variant alleles of a human mu opioid receptor gene of the present invention For example, the present invention extends to a cloning vector comprising an isolated variant allele of a human mu opioid receptor gene and an origin of replication, wherein the predominant or "most common" allele of a human mu opioid receptor gene found in the population comprises a DNA sequence of SEQ ID NO 1 , and a variant allele of the present invention comprises a DNA sequence having a variation in SEQ ID NO 1. wherein the variation comprises G24A,

G779A, or G942A, or combinations thereof

In another embodiment, the present invention extends to a cloning vector comprising an isolated nucleic acid molecule hybridizable under standard hybridization conditions to an isolated variant allele of a human mu opioid receptor gene, and an origin of replication, wherein the predominant or "most common" allele of a human mu opioid receptor gene found in the population comprises a DNA sequence of SEQ ID NO 1, and a variant allele of the present invention comprises a DNA sequence having a variation in SEQ ID NO 1, wherein the variation comprises

G24A, G779A, or

G942A. or combinations thereof

Numerous cloning vectors have applications in the present invention For example, a cloning vector having applications m the present invention includes E coli, bacteriophages such as lambda derivatives, plasmids such as pBR322 derivatives, and pUC plasmid derivatives such as pGEX vectors or pmal-c or pFLAG, to name only a few

Naturally, the present invention extends to expression vectors comprising an isolated variant allele a human mu opioid receptor gene operatively associated with a promoter, wherein the predominant or ' most common' allele of a human mu opioid receptor gene found in the population comprises a DNA sequence of SEQ ID NO 1 , and a variant allele of the present invention comprises a DNA sequence having a variation in SEQ ID NO 1 , wherein the variation comprises G24A,

G779A, or G942A, or combinations thereof

Furthermore, the present invention extends to an expression vector comprising an isolated nucleic acid molecule hybridizable under standard hybridization conditions to an isolated vaπant allele a human mu opioid receptor gene, wherein the isolated nucleic acid molecule is operatively associated with a promoter As set forth above, the predominant or "most common" allele of a human mu opioid receptor gene found in the population comprises a DNA sequence of SEQ ID NO 1 , and a variant allele of the present invention comprises a DNA sequence having a variation in SEQ ID NO 1 , wherein the variation comprises G24A, G779A, or G942A, or combinations thereof

Numerous promoters have applications in an expression vector of the present invention, including but not limited to immediate early promoters of hCMV, early promoters of SV40, early promoters of adenovirus, early promoters of vaccinia, early promoters of polyoma, late promoters of SV40, late promoters of adenovirus. late promoters of vaccinia, late promoters of polyoma, the lac the trp system, the TAC system, the TRC system, the major operator and promoter regions of phage lambda, control regions of fd coat protein, 3- phosphoglycerate kinase promoter, acid phosphatase promoter, or promoters of yeast α mating factor, to name onlj a few

In addition, the present invention extends to a unicellular host transformed or transfected with an expression vector of the present invention Examples of hosts which can be transformed or transfected with an expression vector of the present invention, and have applications m the present invention, include, but are not limited to, E coli, Pseudomonas, Bacillus, Streptomyces, yeast, CHO, RI 1. B-W, L-M COS1, COS7, BSC1 , BSC40, BMT10 or Sf9 cells

Naturally, the present invention extends to a method ot producing a variant human mu opioid receptor comprising an amino acid sequence having a variation in SEQ ID NO 2, wherein the variation comprises Arg260Hιs An example of such a method comprises the steps of culturing a unicellular host transformed or transfected with an expression vector comprising an isolated variant allele a human mu opioid receptor gene, wherein the predominant or "most common" allele of a human mu opioid receptor gene found in the population comprises a DNA sequence of SEQ ID NO 1 , and a variant allele of the present invention comprises a DNA sequence having a variation in SEQ ID NO 1 , wherein the variation comprises G779A, operatively associated with a promoter The transformed or transfected unicellular host is then cultured under conditions that provide for expression of the variant allele of the human mu opioid receptor gene The variant human mu opioid receptor produced from such induced expression is then recovered from the unicellular host Another example comprises the steps of culturing a unicellular host transformed or transfected with an expression vector comprising an isolated nucleic acid molecule operatively associated with a promoter, wherein the isolated nucleic acid molecule is hybridizable under standard hybridization conditions to a variant allele a human mu opioid receptor gene, and the predominant or "most common" allele of a human mu opioid receptor gene found in the population comprises a DNA sequence of SEQ ID NO 1 , and the vaπant allele comprises a DNA sequence having at least one variation in SEQ ID NO 1, wherein the at least one variation comprises G779A The transformed or transfected unicellular host is then cultured under conditions that provide for expression of the variant allele of the human mu opioid receptor gene The variant human opioid receptor produced from such induced expression is then recovered from the unicellular host

Furthermore, the present invention extends to an isolated variant allele of a human mu opioid receptor gene, wherein the predominant or "most common" allele of the human mu opioid receptor gene comprises a DNA sequence of SEQ ID NO 1 , and a variant allele of the present invention comprises a DNA sequence having at least two variations in SEQ ID NO 1 , wherein the variations comprise

A118G,

C17T, G24A,

G779A, or

G942A

The present invention further extends to an isolated variant allele of a human mu opioid receptor gone comprising a DNA sequence having at least two variations in SEQ ID NO. l , as stated above, which is detectably labeled Examples of detectable labels having applications in this embodiment include, but are not limited to. a radioactive element, a chemical which fluoresces, or an enzyme

The present invention further extends to an isolated nucleic acid molecule hybridizable under standard hybridization conditions to an isolated variant allele of a human mu opioid receptor gene, wherein the predominant or most common" allele of the human mu opioid receptor gene comprises a DNA sequence of SEQ ID NO 1 , and a variant allele of the present invention comprises a DNA sequence having at least two variations in SEQ ID NO 1 , wherein the variations comprise A118G,

C17T, G24A,

G779A, or G942A

Namrally, the present invention extends to a detectably labeled isolated nucleic acid molecule hybridizable under standard hybridization conditions to an isolated variant allele of a human mu opioid receptor comprising a DNA sequence having at least two variations in SEQ ID NO 1 , wherein the variations comprise A118G, C17T, G24A,

G779A, or G942A

Examples of detectable labels having applications in this embodiment of the invention include, but are not limited to, a radioactive element, a chemical which fluoresces, or an enzyme

Furthermore, the present invention extends to an isolated variant allele of a human mu opioid receptor gene comprising a DNA sequence having at least two variations in SEQ ID NO 1 , as set forth above, wherein the predominant or most common allele ot a human mu opioid receptor gene encodes a human mu opioid receptor comprising an ammo acid sequence of SEQ ID NO 2, and a variant allele of the present invention encodes a human mu opioid receptor comprising an amino acid having at least two variations in SEQ ID NO 2, wherein the variations comprise Asn40Asp or conserved variants thereof

AlaόVal or conserved variants thereof, or Arg260Hιs or conserved variants thereof The present invention further extends to an isolated nucleic acid molecule hybridizable under standard hybridization conditions to an isolated variant allele of a human mu opioid receptor gene comprising a DNA sequence having at least two variations in SEQ ID NO l, wherein the variations comprise A118G,

C17T,

G24A,

G779A, or

G942A, such that the isolated nucleic acid molecule encodes a variant human mu opioid receptor comprising an amino acid sequence having at least two variations m SEQ ID NO 2, wherein the variations comprise

Asn40Asp or conserved variants thereof,

AlaόVal or conserved variants thereof, or Arg260Hιs or conserved variants thereof

Naturally, the present invention extends to a vaπant human mu opioid receptor comprising an ammo acid sequence having at least two variations in SEQ ID NO 2, wherein the variations comprise Asn40Asp or conserved variants thereof,

AlaόVal or conserved variants thereof, or

Arg260Hιs or conserved variants thereof

Moreover, the present invention extends to an antibody having as an immunogen a human mu opioid receptor comprising an ammo acid sequence having at least two variations in SEQ ID NO 2, wherein the variations comprise Asn40Asp or conserved variants thereof, AlaόVal or conserved variants thereof, or Arg260Hιs or conserved variants thereof An antibody of the present invention can be a polyclonal antibody, a monoclonal antibody, or a chimeric antibody Moreover, an antibody of the present invention can be detectably labeled Examples of detectable labels having applications in an antibody of the present invention include, but are not limited to, a radioactive element, a chemical which fluo- resces, or an enzyme

Furthermore, the present invention extends to a cloning vector comprising an isolated variant allele of a human mu opioid receptor gene and an origin of replication, wherein the predominant or "most common" allele of the human mu opioid receptor gene present in the population comprises a DNA sequence of SEQ ID NO 1, and a variant allele of the present invention comprises a DNA sequence having at least two variations m SEQ ID NO 1 , wherein the variations comprise

A118G, C17T,

G24A,

G779A, or

G942A

In addition, the present invention extends to a cloning vector comprising an isolated nucleic acid molecule hybridizable under standard hybridization conditions to a variant allele of a human mu opioid receptor and an origin of replication wherein the vaπant allele comprises a DNA sequence having at least two variations m SEQ ID NO 1 , wherein the variations comprise A118G,

C17T, G24A, G779A, or G942A, and an origin of replication

Numerous cloning vectors have applications in this embodiment of the present invention Examples of such vectors include, but are not limited to, E coli, bacteriophages, such as lambda derivatives, plasmids such as pBR322 derivatives, and pUC plasmid derivatives such as pGEX vectors or pmal-c or pFLAG to name only a few

Naturally, the present invention extends to an expression vector comprising an isolated variant allele of a human mu opioid receptor gene operatively associated with a promoter, wherein such an isolated vaπant allele comprises a DNA sequence having at least two variations in SEQ ID NO 1 , wherein the variations comprise

A118G,

C17T, G24A,

G779A, or

G942A

In addition, the present invention extends to an expression vector comprising an isolated nucleic acid molecule operatively associated with a promoter, wherein the isolated nucleic acid molecule is hybridizable under standard hybridization conditions to an isolated variant allele of a human mu opioid receptor gene comprising a DNA sequence having at least two variations in SEQ ID NO 1 wherein the variations comprise

A118G. C17T,

G24A,

G779A, or

G942A

Numerous promoters are available and have applications in an expression vector of the present invention Examples of promoters having applications include, but are not limited to immediate early promoters of hCMV, early promoters of SV40, early promoters of adenovirus, early promoters of vaccinia, early promoters of polyoma, late promoters of SV40, late promoters of adenovirus. late promoters of vaccinia late promoters of polyoma, the lac the trp system, the TAC system, the TRC system, the major operator and promoter regions of phage lambda, control regions of fd coat protein, 3-phosphoglycerate kinase promoter, acid phosphatase promoter, or promoters of yeast α mating factor, to name only a few

Naturally, the present invention extends to a unicellular host transformed or transfected with an expression vector of the present invention Examples of unicellular hosts having applications in an embodiment of the present invention include, but are not limited to, E coli, Pseudonomas, Bacillus, Streptomyces. yeast, WHO, RI 1 , B-W, L-M, COS1 , COS7, BSC1, BSC40, BMT10 or Sf9 cells

In another embodiment, the present invention extends to a method for producing a human mu opioid receptor comprising an ammo acid sequence having at least two variations in SEQ ID NO 2, wherein the variations comprise

Asn40Asp or conserved variants thereof,

AlaόVal or conserved variants thereof, or

Arg260Hιs or conserved variants thereof

More specifically, an example of a method for producing such a human mu opioid receptor comprises the steps of culturing a unicellular host transformed or transfected with an expression vector compπsmg an isolated vaπant allele of a human mu opioid receptor gene operatively associated with a promoter, wherein the vaπant allele comprises a DNA sequence having at least two variations m SEQ ID NO 1 , wherein the variations comprise A118G,

C17T, G24A, G779A, or G942A, under conditions that provide for expression of the isolated vaπant allele of a human mu opioid receptor gene After expression, a variant human mu opioid receptor is recovered from the unicellular host

In another example, a method for producing a human mu opioid receptor of the present invention comprises the steps of culturing a unicellular host transformed or transfected with an expression vector comprising an isolated nucleic acid molecule operatively associated with a promoter, wherein the isolated nucleic acid molecule is hybridizable under standard hybridization conditions to an isolated variant allele of a human mu opioid receptor gene comprising a DNA sequence having at least two variations in SEQ ID NO 1 , wherein the variations comprise A118G, C17T, G24A, G779A, or

G942A, under conditions that provide for expression of the isolated nucleic acid molecule The variant human mu opioid receptor produced from the expression is then recovered from the unicellular host

Moreover, Applicants have discovered that β-endoφhm, an endogenous opioid comprising 31 ammo acid residues, and binds to the human mu opioid receptor, has a binding affinity approximately three times greater for a variant human mu opioid receptor produced from expression of a variant allele of the human mu opioid receptor gene comprising an Al 18G variation in SEQ ID NO 1, than for a human mu opioid receptor produced from expression of the predominant or most common' allele of the human mu opioid receptor gene Also, β-endoφhm induced activity of a receptor produced from the expression of a variant allele of a human mu opioid receptor gene or an isolated nucleic acid molecule hybridizable thereto under standard hybridization conditions comprising the A118G polymoφhism effected the receptor s activation of GIRK channels via a G protein-mediated mechanism relative to the activity of a receptor produced from the expression of the predominant or most common allele β-endoφhin is present in both the central nervous system (CNS) and the periphery It plays a role m endogenous analgesia, as well as in response to exposure to a potential addictive agent, such as heroin or alcohol For example, as a neuropeptide, it can modulate neurotransmitter actions in the CNS to mediate antmoception It is also of potential importance for the pathophysiology of addictive diseases Given the diverse roles of β-endorphin the presence of a variant allele of a human mu opioid receptor gene comprising at least one variation in SEQ ID NO 1 , wherein the variation comprises A118G, in a subject may alter the subject's perception of pain, susceptibility to develop opioid addiction following exposure to opioids as well as addictions to other drugs that alter the opioid system, and reaction of the subject towards a therapeutic agent designed to treat pam, such as moφhine or towards a therapeutic agent designed to treat a specific addiction In fact, the inventors herein have also discovered that the Al 18G variant polymor- phism is present in the human mu opioid receptor gene of at least one subset of nonaddicts, an Hispanic study subject group, in a statistically significant level (P=0 0041) Hence, the presence of the A118G polymoφhism in a subject, with increased β-endorphin affinity and effects on activation of GIRK channels as described above, is expected to decrease the subject's perception of pam, protect the subject against potential addiction to opioids such as heroin and likewise influence the subject's reaction to therapeutic agents designed to treat the at least one addictive disease of the subject

Furthermore, Applicants have discovered a variant allele of a human mu opioid receptor gene comprising a variation in SEQ ID NO 1, wherein the variation comprises C17T, is present at a statistically significant greater frequency in the genome of at least one defined subset of addicts suffering from at least one addictive disease, than m the genomes of people not suffering from such a disease Hence, the presence of such a variant allele of a human mu opioid receptor gene may alter perception of pain, susceptibility to develop opioid addiction following exposure to opioids, and influence the subject's reaction to therapeutic agents designed to treat the at least one addictive disease of the subject The inventors herein have discovered that the C17T variant mu opioid receptor has a β- endoφhin binding affinity approximately 0 72 times that of the human mu opioid receptor produced from expression of the predominant or "most common" allele of the human mu opioid receptor gene The decreased binding affinity of this variant is in contrast to the increased affinity of the A118G variant mentioned above In addition, one of the important indices of cellular functioning of the mu opioid receptor is the inhibition of adenylyl cyclase activity following agonist binding to the receptor Theinventors herein have discovered that the C17T variant mu opioid receptor is less sensitive to two endogenous opioids, β-endorphin and leu-enkephahn, than the receptor produced by the "most common" allele the EC50 values differed by a factor of approximately 2 7 and 2 8, respectively Hence, the presence of the C17T polymoφhism in a subject, with decreased β-endoφhin affinity and decreased sensitivity to endogenous opioids as described above, is expected to increase the subject's perception of pain, increase susceptibility to potential addiction to opioids such as heroin and likewise influence the subject's reaction to therapeutic agents designed to treat the at least one addictive disease of the subject

Accordingly, the present invention extends to a method for determining a susceptibility m a subject to at least one addictive disease, comprising the steps of removing a bodily sample comprising a first and second allele of a human mu opioid receptor gene from the subject, and determining whether the first allele comprises a human mu opioid receptor gene comprising a DNA sequence having at least one variation in SEQ ID NO 1 , wherein the variation comprises A118G, or C17T

The present of at least one of these variations in the human mu opioid receptor gene of the first allele is expected to be indicative of the subject's susceptibility to at least one addictive disease relative to the susceptibility of a standard to at least one addictive disease, wherein the standard comprises a first allele comprising a human mu opioid receptor gene having a DNA sequence of SEQ ID NO 1

Another embodiment of the method for determining a susceptibility in the subject to at least one addictive disease, as described above, comprises the further step of determining whether the second allele of the bodily sample of the subject comprises a human mu opioid receptor gene comprising a DNA sequence having at least one variation in SEQ ID NO 1. wherein the variations comprise A118G, or C17T The presence of at least one variation the second allele of the bodily sample is expected to be indicative of the subject's susceptibility to at least one addictive disease relative to a standard in which both alleles of a human mu opioid receptor gene comprise a DNA sequence of SEQ ID NO 1

In particular, the presence of an Al 18G variation in the DNA sequence of the human mu opioid receptor gene of the first and/or second alleles in the bodily sample from the subject is expected to be indicative of a decreased susceptibility of the subject to at least one addictive disease relative to the standard

Moreover, the presence of a C17T variation in the DNA sequence of the human mu opioid receptor gene of the first and/or second alleles in the bodily sample from the subject is expected to be indicative of an increased susceptibility of the subject to at least one addictive disease relative the susceptibility of the standard to at least one addictive disease, wherein both alleles of the standard comprise a human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO 1 Examples of at least one addictive disease includes, but is not limited to opioid addiction, cocaine addiction or addiction to other psychostimulants, nicotine addiction, barbiturate or sedative hypnotic addiction, anxiolytic addiction, or alcohol addiction

In another embodiment, the present invention extends to a method for determining a susceptibility to at least one addictive disease m a subject relative to susceptibility to at least one addictive disease in a standard, involving the detection of variations in the human mu opioid receptor itself, and particularly, determining whether a variant human mu opioid receptor is present in a bodily sample from a subject Such a method comprises the steps of removing a bodily sample comprising a human mu opioid receptor from the subject, and determining whether the human mu opioid receptor present in the sample is a variant human mu opioid receptor of the invention, wherein the variant human mu opioid receptor comprises an amino acid sequence having at least one variation in SEQ ID NO 2, wherein the variation comprises Asn40Asp or conserved variants thereof, or

AlaόVal or conserved variants thereof, The presence of at least one variation is expected to be indicative of the subject's susceptibility to at least one addictive disease relative to susceptibility to at least one addictive disease in a standard, wherein the human mu opioid receptor of the standard comprises an ammo acid sequence of SEQ ID NO 2

In particular, a variant human mu opioid receptor present in the sample comprising an amino acid sequence having at least one variation in SEQ ID NO 2, wherein the variation comprises Asn40Asp or conserved variants thereof, is expected to be indicative of a decreased susceptibility to at least one addictive disease in the subject relative susceptibility to the at least one addictive disease in the standard, wherein the human mu opioid receptor of the standard comprises an amino acid sequence of SEQ ID NO 2

In contrast, a variant human mu opioid receptor present in a sample from the subject comprising a variation in SEQ ID NO 2, wherein the variation comprises AlaόVal or conserved variants thereof, indicates an increased susceptibility to addictive diseases m the subject relative to a standard having a human mu opioid receptor comprising an amino acid sequence of SEQ ID NO 2 As explained above, at least one addictive disease includes, but is not limited to, opioid addiction, cocaine addiction or addiction to other psychostimulants, nicotine addiction, barbiturate or sedative hypnotic addiction, anxiolytic addiction, or alcohol addiction

Furthermore, the present invention extends to a method for determining a susceptibility to pain in a subject relative to susceptibility to pain in a standard, comprising the steps of removing a bodily sample comprising a first and second allele of a human mu opioid receptor gene from the subject, and determining whether the first allele comprises a human mu opioid receptor gene comprising a DNA sequence having at least one variation in SEQ ID NO- 1 , wherein the variation comprises A118G, or C17T The presence of at least one variation in the human mu opioid receptor gene of the first allele is expected to be indicative of a decreased oi increased susceptibility to pain in the subject relative to susceptibility to pain in the standard, wherein the first allele of the standard comprises a human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO 1

Moreover, a method for determining a susceptibility to pain in a subject may further comprise the step of determining whether the second allele comprises a human mu opioid receptor gene comprising a DNA sequence having at least one variation in SEQ ID NO 1 , wherein the variation comprises A118G, or C17T The presence of the at least one variation in the human mu opioid receptor gene of the second allele of the bodily sample from the subject is expected to be indicative of an increased or decreased susceptibility to pain in the subject relative to the susceptibility to pain in the standard, wherein the second allele in the standard comprises a human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO 1

At least one variation in the human mu opioid receptor gene of the first and/or second allele of the bodily sample taken from the subject, wherein the variation comprises A118G, is expected to be indicative of a decreased susceptibility to pain in the subject relative susceptibility of pain in the standard, wherein the human mu opioid receptor gene of the first and/or second allele of the standard comprises a DNA sequence of SEQ ID NO 1

Furthermore, the presence of at least one variation comprising C17T in the human mu opioid receptor gene of the first and/or second allele of the bodily sample from the subject is expected to be indicative of an increased susceptibility to pain in the subject relative to the susceptibility to pain in the standard, wherein the first and/or second allele of the standard comprise a human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO 1

In another embodiment, the present invention extends to a method for determining a susceptibility to pain in a subject relative to susceptibility to pain in a standard by examining a bodily sample taken from the subject for the presence of a variant human mu opioid receptor Such a method comprises the steps of removing a bodily sample comprising a human mu opioid receptor from the subject, and determining whether the human mu opioid receptor present in the sample is a variant human mu opioid receptor of the invention, 1 e , comprises an amino acid sequence having at least one variation in SEQ ID NO 2, wherein the variation comprises

Asn40Asp or conserved variants thereof, or AlaόVal or conserved variants thereof, such that the presence of at least one variation is expected to be indicative of the subject's susceptibility to pain relative to susceptibility to pain in the standard, wherein the human mu opioid receptor of the standard comprises an amino acid sequence of SEQ ID NO 2

In particular, the presence of a variant human mu opioid receptor comprising an amino acid sequence having at least one variation in SEQ ID NO 2 wherein the variation comprises Asn40Asp or conserved variants thereof, is expected to be indicative of a decreased susceptibility to pain in the subject relative to susceptibility to pain in the standard, wherein the human mu opioid receptor of the standard comprises an amino acid sequence of SEQ ID NO 2

Furthermore, the presence of a variant human mu opioid receptor comprising an amino acid sequence having a variation in SEQ ID NO 2, wherein the variation comprises AlaόVal or conserved variants thereof, in a bodily sample taken from a subject is expected to be indicative of an increased susceptibility to pain in the subject relative to susceptibility to pain m the standard, wherein the human mu opioid receptor of the standard comprises an amino acid sequence of SEQ ID NO 2

Once a susceptibility to pain in the subject has been determined, it is possible for attending medical professionals treating the subject to administer to an appropriate, or therapeutically effective amount of pam reliever in order to induce analgesia in the subject Administration of such an amount is important to the subject because, should an inappropriate amount of pa reliever be administered, the subject may not experience analgesia, and may be exposed to potentially deleterious side effects of the pam reliever, such as induction of addiction to the pain reliever, brain damage, or death

Consequently, the present invention extends to a method for determining a therapeuticallv effective amount of pain reliever to administer to a subject m order to induce analgesia in the subject relative to a therapeutically effective amount of the pain reliever to administer to a standard in order to induce analgesia in the standard wherein the method comprises determining a susceptibility to pain in the subject relative to susceptibility to pain in the standard The susceptibility of pain in the subject is expected to be indicative of the therapeutically effective amount of the pain reliever to administer to the subject to induce analgesia in the subject relative to the amount of the pain reliever to administer to the standard to induce analgesia in the standard

Hence, the present invention extends to a method for determining a therapeutically effective amount of pain reliever to administer to a subject in order to induce analgesia in the subject relative to a therapeutically effective amount of the pain reliever to administer to a standard in order to induce analgesia in the standard wherein the method comprises the steps of removing a bodily sample comprising a first and second allele of a human mu opioid receptor gene from the subject, and determining whether the first allele comprises a human mu opioid receptor gene comprising a DNA sequence having at least one variation in SEQ ID NO 1 , wherein the variation comprises A118G, or C17T The presence of at least one variation m the human mu opioid receptor gene of the first allele from the bodily sample is expected to be indicative of the therapeutically effective amount of pain reliever to administer to the subject to induce analgesia in the subject relative to the therapeutically effective amount of pam reliever to administer to the standard to induce analgesia in the standard, wherein the standard comprises a first allele comprising a human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO 1

Moreover, the present invention further extends to a method for determining a therapeutically effective amount of pain reliever to administer to a subject in order to induce analgesia in the subject relative to a therapeutically effective amount of pain reliever to administer to a standard to induce analgesia therein, further comprising the steps of removing a bodily sample comprising a first and second allele comprising a human mu opioid receptor gene from the subject, and determining whether the second allele of the bodily sample comprises a human mu opioid receptor gene comprising a DNA sequence comprising at least one variation in SEQ ID NO 1. wherein the variation comprises A118G, or

C17T The presence of at least one variation in the human mu opioid receptor gene of the first and/or second allele ot the bodily sample is expected to be indicative of the therapeutically effective amount ot pain reliever to administer to the subject to induce analgesia therein relative to the amount ot pain reliever to administer to a standard to induce analgesia therein, wherein the first and second alleles of the standard comprise a human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO 1

More particularly, a variation of the human mu opioid receptor gene of the first and/or second allele from the bodily sample taken from the subject, comprising a DNA sequence comprising a variation in SEQ ID NO 1 , wherein the variation comprises A118G, is expected to be indicative of a decreased susceptibility to pain in the subject relative susceptibility of pain in the standard Consequently, the subject requires a decreased therapeutically effective amount of pam reliever in order to induce analgesia therein relative to the therapeutically effective amount of pain reliever needed to induce analgesia in the standard

In contrast, a variation of the DNA sequence of the human mu opioid receptor gene of the first and/or second allele from the bodily sample taken from the subject, comprising C17T, is expected to be indicative of an increased susceptibility to pain in the subject relative to the susceptibility to pain in the standard Hence, the therapeutically effective amount of pain reliever to administer to the subject in order to induce analgesia therein is greater than the therapeutically effective amount of pain reliever to administer to the standard to induce analgesia therein

In another embodiment, the present invention extends to determining a therapeutically effective amount of pam reliever to administer to a subject in order to induce analgesia in the subject, by examining a bodily sample from a subject for the presence of a variant human mu opioid receptor comprising an ammo acid sequence having a variation in SEQ ID NO 2 More specifically, the present invention extends to a method for determining a therapeutically effective amount of pam reliever to administer to a subject in order to induce analgesia in the subject, relative to a therapeutically effective amount of pain reliever to administer to a standard in order to induce analgesia in the standard, comprising the steps of removing a bodily sample comprising a human mu opioid receptor from the subject, and determining whether the human mu opioid receptor present m the sample comprises an amino acid sequence having at least one variation in SEQ ID NO 2, wherein the variation comprises Asn40Asp or conserved variants thereof, or

AlaόVal or conserved variants thereof, such that the presence of at least one variation is expected to be indicative of the therapeutically effective amount of pain reliever to administer to the subject to induce analgesia therein relative to the therapeutically effective amount of pain reliever to administer to induce analgesia in the standard, wherein the human mu opioid receptor of the standard comprises an ammo acid sequence of SEQ ID NO 2

In particular, the presence of a variant human mu opioid receptor comprising an ammo acid sequence having a variation in SEQ ID NO 2, wherein the variation comprises Asn40Asp or conserved variants thereof m the sample from the subject, is expected to be indicative of a decreased therapeutically effective amount of pain reliever to administer to the subject to induce analgesia therein relative to the therapeutically effective amount of pam reliever to administer to the standard in order to induce analgesia therein In contrast, the presence of a vaπant human mu opioid receptor m the sample from the subject, wherein the receptor comprises an amino acid sequence have a variation in SEQ ID NO 2, wherein the variation comprises AlaόVal or conserved variants thereof, is expected to be indicative of an increased therapeutically effective amount of pain reliever to admmis- ter to the subject in order to induce analgesia therein relative to the therapeutically effective amount to administer to the standard to induce analgesia therein

Examples of pa relievers having applications m this embodiment of the present invention include, but are not limited to, moφhine, codeine, dihydromoφhm, mepeπdme, metha- done, fentanyl and its congeners, butoφhenol, nalbuphme, LAAM, or propoxyphme, to name only a few

Furthermore, the present invention extends to a method for determining a therapeutically effective amount of a therapeutic agent for treating at least one addictive disease to administer to a subject suffering from at least one addictive disease, relative to a therapeutically effective amount of the therapeutic agent to administer to a standard suffering from the at least one addictive disease As a result, the dosage of therapeutic agent administered to an addict can be tailored" to the addict's needs based upon the addict's genotype An example of such a method comprises the steps of removing a bodily sample from the subject, wherein the bodily sample comprises a first and second allele of the human mu opioid receptor gene, and determining whether the first allele comprises a DNA sequence having at least one variation in SEQ ID NO 1 , wherein the variation comprises A118G, or C17T The presence of the at least one variation in the human mu opioid receptor gene of the first allele in the bodily sample from the subject is related to the therapeutically effective amount of therapeutic agent to administer to the subject to treat the subject's at least one addictive disease, relative to the therapeutically effective amount of the therapeutic agent to administer to the standard suffering from the at least one addictive disease, wherein the first and second allele of the standard comprise a human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO 1

Furthermore, a method for determining a therapeutically effective amount of therapeutic agent to administer to a subject suffering from at least one addictive disease may further comprise an additional step of determining whether the second allele of the bodily sample taken from the subject comprises a human mu opioid receptor gene comprises a DNA sequence having at least one variation in SEQ ID NO 1 , wherein the at least one variation comprises

A118G, or

C17T Such a variation in the first and/or second allele of the bodily sample is expected to be indicative of the therapeutically effective amount of the therapeutic agent to administer to the subject to treat the at least one addictive disease of the subject relative to the therapeutically effective amount of the therapeutic agent to administer to the standard suffering from the at least one addictive disease

The presence of a human mu opioid receptor gene comprising a DNA sequence having at least one variation in SEQ ID NO 1 in the first and/or second alleles of the bodily sample taken from the subject, wherein the variation comprises Al 18G is expected to be indicative of a decreased therapeutically effective amount of the therapeutic agent to administer to the subject to treat the at least one addictive disease of the subject, relative to the therapeutically effective amount of the therapeutic agent to administer to the standard suffering from the at least one addictive disease, wherein the two alleles of the standard comprise a human mu opioid receptor gene comprising a DNA sequence ot SEQ ID NO 1

Furthermore, the presence of a human mu opioid receptor gene comprising a DNA sequence having at least one variation of SEQ ID NO 1 in the first and/or second allele of the bodily sample taken from the subject, wherein the variation comprises C17T, is expected to be indicative of an increased therapeutically effective amount of the therapeutic agent to administer to treat the at least one addictive disease of the subject relative to the therapeutically effective amount of the therapeutic agent to administer to the standard suffering from the at least one addictive disease to treat the at least one addictive disease in the standard, wherein the alleles of the standard comprise a human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO 1

In another embodiment, the present invention extends to determining a therapeutically effective amount of a therapeutic agent for treating at least one addictive disease to administer to a subject suffering from at least one addictive disease by examining a bodily sample from a subject for the presence of a variant human mu opioid receptor comprising an amino acid sequence having at least one variation in SEQ ID NO 2 More specifically, the present invention extends to a method for determining a therapeutically effective amount of therapeutic agent for treating at least one addictive disease to administer to a subject suffering from the at least one addictive disease, relative to a therapeutically effective amount of the therapeutic agent to administer to a standard suffering from the at least one addictive disease, wherein the method comprises the steps of removing a bodily sample comprising a human mu opioid receptor from the subject, and determining whether the human mu opioid receptor present in the sample comprises an amino acid sequence having at least one variation in SEQ ID NO 2, wherein the variation comprises Asn40Asp or conserved variants thereof, or AlaόVal or conserved variants thereof The presence of at least one variation in the human mu opioid receptor of the bodily sample is expected to be indicative of therapeutically effective amount of the therapeutic agent to administer to the subject to treat the at least one addictive disease of the subject relative to the therapeutically effective amount of the therapeutic agent to administer to the standard suffering from the at least one addictive disease, wherein the human mu opioid receptor of the standard comprises an amino acid sequence of SEQ ID NO 2

In particular, the presence of a variant human mu opioid receptor comprising an amino acid sequence having at least one variation in SEQ ID NO 2 comprising Asn40Asp or conserved variants thereof in the bodily sample of the subject is expected to be indicative of a decreased therapeutically effective amount of the therapeutic agent to administer to the subject to treat the at least one addictive disease in the subject relative to the therapeutically effective amount of the therapeutic agent to administer to the standard to treat the at least one addictive disease therein

Furthermore, the presence of a variant human mu opioid receptor comprising an amino acid sequence having at least one variation in SEQ ID NO 2, wherein the variation comprises AlaόVal or conserved variants thereof in the bodily sample of the subject is expected to be indicative of an increased therapeutically effective amount of the therapeutic agent to administer to the subject order treat the at least one addictive disease in the subject relative to the therapeutically effective amount of the therapeutic agent to administer to the standard suffering from the at least one addictive disease Examples of at least one addictive disease includes, but is not limited to opioid addiction, cocaine addiction or addiction to other psychostimulants, nicotine addiction, barbiturate or sedative hypnotic addiction, anxiolytic addiction, or alcohol addiction Furthermore, examples of therapeutic agents having applications of the present invention include methadone, LAAM, maltrexone, or bupπnoφhine, to name only a few

Furthermore, the present invention extends to a method for diagnosing a disease or disorder related to a physiological function regulated by the HPA or HPG axes of the neuroendocπne system The HPA and HPG axes play an important role in regulation of numerous physiological activities such as reproductive and sexual function, gastrointestinal motihty, immune response to an antigen, or an ability to withstand stress Furthermore, the HPA and HPG axes exert such regulatory control via the production of endogenous opioids that interact with opioid in many locations of the body In particular, in the HPG axis, the mu opioid receptor is centrally involved in tonic regulation of the luteinizmg hormone, particularly in its pulsatile release Furthermore, in the HPA axis, the mu opioid receptor modulates corticotropin releasing factor/hormone (CRF or CRH) in the hypothalamus which m turn modulates production of pro-opiomelanocortin (POMC) in the pituitary which is processed into several active peptides such as ACTH, which stimulates the adrenal cortex to release the stress hormone cortisol in humans, which in turn provides the stress response to environmental stimuli Furthermore, modulated mu opioid receptor activity can lead to modulation of most cellular and humoral immunity including that mediate through T cells, B cells, cytokines, and chemokines The pathophysiology ot immune disorders may therefore be influenced by pharmacotherapies that modulate the activity of the mu opioid receptor Moreover, gastrointestinal motihty is modulated by modulation of opioid receptor treatment, and diagnosis of a disease or disorder related to gastrointestinal motihty (e g constipation) may be facilitated by knowledge of intrinsic mu opioid receptor motihty

Applicants have discovered that the binding affinity of an opioid receptor, such as a mu opioid receptor with an endogenous opioid ligand, such as β-endoφhin. is expected to modulate such physiological activities Hence, the binding affinity of variant mu opioid receptors explained above, for endogenous opioid ligands such as β-endoφhin, is expected to modulate those physiological activities regulated by the HPA and HPG axes relative to those physiological activities in a standard having mu opioid receptors produced from the predominant or "most common" allele of the mu opioid receptor gene comprising a DNA sequence of SEQ ID NO 1 As the result, the present invention extends to a method of diagnosing a disease or disorder related to a physiological function regulated by the HPA or HPG axes Examples of physiological functions regulated by the HPA and the HPG include, but are not limited to sexual or reproductive functions, gastrointestinal motihty, immune response, or ability to withstand stress Such a method comprises the steps of removing a bodilv sample comprising a first and second allele of a human mu opioid receptor gene from the subject, and determining whether the first allele comprises a human mu opioid receptor gene comprising a DNA sequence having at least one variation in SEQ ID NO 1. wherein the variation comprises A118G. or C17T

The presence of at least one variation in the human mu opioid receptor gene of the first allele is expected to be indicative of a disorder related to a physiological function regulated by the HPA or GPA, such as sexual or reproductive functions, gastrointestinal motihty, immune response, and the ability to withstand stress, wherein the first allele of the standard comprises a human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO 1

Moreover, a method for diagnosing a disease or disorder related to a physiological function regulated by the HPA or GPA, as described above may further comprise the step of determining whether the second allele of the bodily sample comprises a human mu opioid receptor gene comprising a DNA sequence having at least one variation in SEQ ID NO 1 , wherein the variation comprises A118G, or C17T The presence of the at least one variation in the human mu opioid receptor gene of the second allele of the bodily sample from the subject may be expected to be indicative of a disease or disorder related to sexual and reproductive functions, gastrointestinal motihty, immune response, or the ability of the subject to withstand stress At least one variation m the human mu opioid receptor gene of the first and/or second allele of the bodily sample taken from the subject, wherein the variation comprises A118G, is expected to be indicative of decreased HPA and HPG activity, resulting m increased sexual or reproductive functions, increased gastrointestinal motihty, increased immune response, or increased ability to withstand stress relative to the levels of such function observed in a standard

Furthermore, the presence of at least one variation comprising C17T in the human mu opioid receptor gene of the first and/or second allele of the bodily sample from the subject is expected to be indicative increased HPA or HPG activity, resulting in decreased sexual or reproductive function, decreased gastrointestinal motihty, decreased immune response, or decreased ability to withstand stress relative to the levels of such function observed m a standard

In another embodiment, the present invention extends to a method for diagnosing a disease or disorder related to a physiological function regulated by the HPA or GPA by examining a bodily sample taken from the subject for the presence of a variant human mu opioid receptor Such a method comprises the steps of removing a bodily sample comprising a human mu opioid receptor from the subject, and determining whether the human mu opioid receptor present in the sample is a vaπant human mu opioid receptor of the invention, l e , comprises an ammo acid sequence having at least one variation in SEQ ID NO 2, wherein the variation comprises

Asn40Asp or conserved variants thereof, or AlaόVal or conserved variants thereof, such that the presence of at least one variation is expected to be indicative of a disease or disorder related to a physiological activity regulated by the HPA or HPG axes, such as sexual function or development, gastric motihty, immune response, or the ability of the subject to withstand stress, relative to regulation of such activities in a standard comprising a human mu opioid receptor having an ammo acid sequence of SEQ ID NO 2

In particular, the presence of a variant human mu opioid receptor comprising an ammo acid sequence having at least one variation m SEQ ID NO 2 wherein the variation comprises Asn40Asp or conserved variants thereof, is expected to be indicative decreased HPA and HPG activity, resulting in increased sexual or reproductive functions, increased gastrointestinal motility, increased immune response, or increased ability to withstand stress relative to the levels of such function observed in a standard having a mu opioid receptor comprising an amino acid sequence of SEQ ID NO:2.

Furthermore, the presence of a variant human mu opioid receptor comprising an amino acid sequence having a variation in SEQ ID NO:2, wherein the variation comprises AlaόVal or conserved variants thereof, in a bodily sample taken from a subject is expected to be indicative of increased activity of the HPA and HPG axes, resulting in decreased sexual or reproductive functions, decreased gastrointestinal motility, decreased immune response, or decreased ability to withstand stress relative to the levels of such function observed in a standard having a mu opioid receptor comprising an amino acid sequence of SEQ ID NO:2. Examples of specific diseases or disorders related to regulation of physiological functions by the HPA or HPG axes include infertility, constipation, diarrhea, decreased immune response to antigens relative to a standard, or decreased of ability to withstand stress relative to a standard.

Once a disease or disorder related to a physiological function regulated by the HPA or HPG axes has been diagnosed, it is possible for attending medical professionals treating the subject to select and administer an appropriate therapeutic agent and a therapeutically effective amount of the agent to administer to the subject to treat such a disease or disorder. Consequently, the present invention extends to a method for determining an appropriate therapeutic agent to administer to a subject suffering from a disease or disorder related to a physiological function regulated by the HPA or HPG axes, comprising removing a bodily sample from the subject, and determining the presence of at least one variant allele of a mu opioid receptor gene in the bodily sample, wherein the variant allele comprises a human mu opioid receptor gene comprising a DNA sequence having at least one variation in SEQ ID NO: l , wherein the variation comprises: A118G; or C17T.

The present invention further extends to a method for selecting an appropriate therapeutic agent to administer to a subject suffering from a disease or disorder related to a physiologi- cal function regulated by the HPA or HPG axes as set forth above, further comprising determining whether the bodily sample comprises a second variant allele of the mu opioid receptor gene comprising a DNA sequence having a variation in SEQ ID NO 1, wherein the variation comprises A118G, or

C17T

In particular, should either or both alleles of the mu opioid receptor gene of the bodily sample comprise a DNA sequence having a variation in SEQ ID NO 1 , wherein the variation comprises Al 18G, the mu opioid receptors of the subject are expected to have increased function relative to mu opioid receptors of a standard produced from expression of the predominant or "most common" mu opioid receptor allele comprising a DNA sequence of SEQ ID NO 1 This increased function is expected to result m decreased function of the HPA and HPG axes Hence, an appropriate therapeutic agent for treating a disease or disorder related to decreased activity of the HPA or HPG axes, such as diarrhea can be selected

In contrast, a human mu opioid receptor produced from expression of a variant allele of a mu opioid receptor gene comprising a variation in SEQ ID NO 1 , wherein the variation comprises C17T is expected to have decreased activity relative to a mu opioid receptor produced from expression of the predominant or "most common" allele of the human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO 1 This decreased activity is expected to result in higher activity of the HPA and HPG axes As a result, a medical professional attending the subject is able to select an appropriate therapeutic agent for treating a disease or disorder related to sexual and reproductive functions, such as infertility, gastrointestinal motihty, such as constipation or diarrhea, decreased immune response towards antigens relative to immune response in a standard, or decreased ability to withstand stress relative to ability to withstand stress in a standard

The present invention further extends to commercial test kits suitable for use by a medical professional to determine whether either or both alleles of a bodily sample taken from a subject comprise a DNA sequence having at least one variation in SEQ ID NO 1 , wherein the variation comprises A118G, or C17T

Commercial test kits of the present invention have applications in determining susceptibility of pam m the subject relative to a standard Such kits can also be used to determine a subject's increased or decreased susceptibility to at least one addictive disease relative to susceptibility to at least one addictive disease in a standard Also a therapeutically effective amount of pam reliever to administer to the subject in order to induce analgesia in the subject relative to a therapeutically effective amount of pain reliever to administer to a standard to induce analgesia in the standard can be determined Moreover, a test kit of the present invention has applications m determining a therapeutically effective amount of therapeutic agent for treating at least one addictive disease to administer to a subject suffering from the at least one addictive disease, relative to a therapeutically effective amount of therapeutic agent to administer to a standard suffering from at least one addictive disease Furthermore, test kits of the invention have applications in diagnosing a disease or disorder related to a physiological condition regulated by the HPA or HPG axes of the neuroendocπne system, and m selecting an appropriate therapeutic agent for treating such a disease or disorder, along with a therapeutically effective amount of agent to administer to the subject A standard as used herein comprises two alleles of a human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO 1

Furthermore, a commercial test kit of the present invention can also be used to determine the presence of an isolated variant allele of a human mu opioid receptor gene of the present invention in a bodily sample removed from a subject, which can serve as a genetic marker As explained above, the predominant or ' most common' allele of a human mu opioid receptor gene found in the population comprises a DNA sequence of SEQ ID NO 1 Hence a variant allele comprising a DNA sequence having a variation in SEQ ID NO 1. wherein the variation comprises G24A, G779A, or

G942A, or combinations thereof, can be detected in the bodily sample with a commercial kit of the invention Other variant alleles of the human mu opioid receptor gene of the present invention can be detected with a commercial test kit of the present invention For example, an isolated variant allele of a human mu opioid receptor gene detectable with a commercial kit ot the present invention, comprises a DNA sequence having at least two variations m SEQ ID NO 1 , wherein the variations comprise

A118G,

C17T,

G24A,

G779A, or G942A

Accordingly, a commercial test kit may be prepared for determining the presence of at least one variation in a human mu opioid receptor gene of either or both alleles in a bodily sample taken from a subject wherein the commercial test kit comprises a) PCR oligonucleotide primers suitable for detection of an allele comprising a human mu opioid receptor gene having a DNA sequence with a variation in SEQ ID NO 1 , b) other reagents, and c) directions for use of the kit

The present invention further extends to commercial test kits capable of detecting a variant human mu opioid receptor in a bodily sample taken from a subject Examples of variant human mu opioid receptors that can be detected with a kit of the present invention comprise a variant human mu opioid receptor comprising an amino acid sequence having a variation in SEQ ID NO 2, wherein the variation comprises Arg260Hιs or conserved variants thereof, or a variant human mu opioid receptor comprising an amino acid sequence having at least two variations in SEQ ID NO 2, wherein the variations comprise Asn40Asp or conserved variants thereof,

AlaόVal or conserved variants thereof, or Arg260Hιs or conserved variants thereof Moreover, a commercial test kit of the present invention can be used to determine susceptibility to pa in the subject relative to susceptibility to pain in a standard, a therapeutically effective amount of pain reliever to administer to a subject to induce analgesia m the subject relative to a therapeutically effective amount of pain reliever to administer to a standard to induce analgesia in the standard, a therapeutically effective amount of therapeutic agent for treating at least one addictive disease to administer to a subject suffering from at least one addictive disease, relative to a therapeutically effective amount of therapeutic agent to administer to a standard suffering from the at least one addictive disease, diagnosing a disease or disorder related to a physiological condition regulated by the HPA or HPG axes of the neuroendocπne system, or selecting an appropriate therapeutic agent for treating such a disease or disorder, along with a therapeutically effective amount of such agent to administer to the subject

Accordingly, the present invention extends to a commercial test kit having applications set forth above comprising a predetermined amount of at least one detectably labeled lmmuno- chemically reactive component having affinity for a variant human mu opioid receptor,

(b) other reagents, and

(c) directions for use of the kit

In a further variation the test kit may be prepared and used for the puφoses stated above, which operates according to a predetermined protocol (e g "competitive, " "sandwich, double antibody, ' etc ), and comprises

(a) a labeled component which has been obtained by coupling the human mu opioid receptor of a bodily sample to a detectable label,

(b) one or more additional lmmunochemical reagents of which at least one reagent is a ligand or an immobilized ligand, which ligand comprises

(0 a ligand capable of binding with the labeled component (a),

(n) a ligand capable of binding with a binding partner of the labeled component

(a),

(in) a ligand capable of binding with at least one of the component(s) to be determined, or

(IV) a ligand capable of binding with at least one of the binding partners of at least one of the component(s) to be determined, or

(c) directions for the performance of a protocol for the detection and/or determination of one or more components of an lmmunochemical reaction between the human mu opioid receptor gene of the present invention and a specific binding partner thereto

Accordingly, it is an object of the present invention to provide heretofore unknown variations the DNA sequence of the human mu opioid receptor gene wherein the variations can be used to map the locus of the human mu opioid receptor gene

It is yet another object of the present invention to use heretofore unknown polymoφhisms of an allele of the human mu opioid receptor gene as markers for any kind of disorder related to the human mu opioid receptor, such as an addictive disease, pain, or markers for genes

It is another object of the present invention to provide nucleotides, optionally detectably labeled, hybridizable under standard hybridization conditions to variant alleles of the human mu opioid receptor gene disclosed herein, as well as polypeptides produced from the expression of the variant alleles and nucleotides hybridizable thereto under standard hybridization conditions

It is yet another object of the present invention to provide antibodies, optionally detectably labeled, having immunogens comprising polypeptides produced from the expression of variant alleles of human mu opioid receptor gene, or expression of isolated nucleic acid molecules hybridizable under standard hybridization conditions to variant alleles disclosed herein

It is another object of the present invention to gain insight into a subject's susceptibility to pain This insight can be used to determine a therapeutically effective dose of pain reliever to administer to the subject to induce analgesia therein relative to the therapeutically effective amount of pain reliever administered to a standard to induce analgesia therein, wherein the standard comprises two alleles of the human mu opioid receptor gene compπs- ing a DNA sequence of SEQ ID NO 1 , or a variant human mu opioid receptor comprising an amino acid sequence of SEQ ID NO 2

Such information can be used to tailor a regimen for treating a subject suffering from at least one addictive disease, relative to the therapeutically effective amount of therapeutic agent administered to a standard suffering from at least one addictive disease

It is yet another object of the present invention to provide commercial test kits for attending medical professionals to determine the presence of variant alleles of a human mu opioid receptor gene m a bodily sample taken from a subject The results of such testing can then be used to determine the subject's susceptibility to pain, susceptibility to at least one addictive disease, determining a therapeutically effective amount of pain reliever to administer to the subject m order to induce analgesia, or determining a therapeutically effective amount of therapeutic agent for treating at least one addictive disease to administer to the subject

It is an object of the present invention to determine the activity of a mu opioid receptor in a subject, and use such information to diagnose a disease or disorder related to sexual or reproductive function, gastrointestinal moti ty, immune response, or ability to withstand stress, wherein variant alleles of the mu opioid receptor gene when expressed produce variant mu opioid receptors having activity different from a mu opioid receptor produced from the predominant or most common allele of the mu opioid receptor comprising a DNA sequence of SEQ ID NO 1

It is another object of the present invention to employ Applicants' discovery of a correlation between the activity of a mu opioid and its impact the neuroendocπne system, and particularly on levels of hormones within the body As a result, the level of activity of the mu opioid receptor effects sexual or reproductive function, gastrointestinal motihtv , immune response, or ability to withstand stress Such information can further be used select appropriate therapeutic agents to treat diseases such as infertility, constipation, or diarrhea Further, such information can be used to select appropriate therapeutic agents to increase immune response against an antigen such as a bacterium, a virus or a tumor cell in the subject, and to treat psychiatric diseases or disorders such as obsessive compulsive disorder, schizophrenia, or depression

It is yet another object of the present invention to provide commercial detecting variant alleles of the human mu opioid receptor gene or the presence of a variant human mu opioid receptor in a bodily sample taken from a subject The results of such tests can then be used to gain incite into a subject's ability to withstand pain, susceptibility to addiction, to diagnose a disease or disorder related to a physiological function regulated by the HPA or HPG axes such as sexual and reproductive functions, gastrointestinal motihty, immune response, and the ability of the subject to withstand stress

These and other aspects of the present invention will be better appreciated by reference to the following drawings and Detailed Description

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1: DNA sequence of the A118G polymoφhism Examples of DNA sequences are shown from individuals homozygous for the most common allele (left) (SEQ ID NO 1), heterozygous (center) and homozygous for the Al l 8G variant allele (right) The arrows indicate the position of nucleotide 1 18 with the adjacent sequences shown

Figure 2: Binding of endogenous opioid peptides to the most common (SEQ ID NO 2) and Asn40Asp mu opioid receptors Membrane preparations from cells expressing either the most common (open circles) or the A118G variant (filled squares) receptors were used m binding experiments to displace the [3H]-DAMGO binding Shown are examples of displacement binding for four endogenous peptides Met-enkephahn, dynoφhm A, β- endoφhin. and endo oφhin- 1

Figure 3: Functional comparison of the most common (SEQ ID NO 1) and A118G variant variant human mu opioid receptors in coupling to G protein-activated inwardly rectifying K⁺ (GIRK) channels (A) Example of current trace showing the experimental protocol and calculation method for the agonist-induced response Oocytes were clamped at a holding potential of -80 mV and superfused with different solutions as indicated I_max maximum K⁺ currents evoked by DAMGO at a saturating concentration (100 nM) I_Tal K⁺ currents evoked by the test dose of agonists (B) Dose response curves of receptor activation The tested concentrations of agonists ranged from 0 1 nM to 1 μM The response to a test dose is expressed as the fraction of the maximum activation by 100 nM DAMGO (/,„,/ „_«) Data are presented as mean ± SEM (n=4-5) All oocytes were used only once to avoid desensitization

Figure 4: The nucleic acid sequence of the most common allele of the mu opioid receptor (SEQ ID NO 1) (GENBANK accession number L25119)

Figure 5 Ammo acid sequence of the most common human mu opioid receptor (SEQ ID NO 2) referred to hMORl, which is compared to the rat homologs of the mu (rMORl) (SEQ ID NO 3), delta (rDORl) (SEQ ID NO 4) and kappa (rKOR) (SEQ ID NO 5) opioid receptor amino a£ id sequences by the use the program PILEUP Boldface type and shading, transmembrane domain candidates, *, consensus sites for N-hnked glycosylation, italics, amino acid residues different between rat and human mu opioid receptor, @, indicates intron/exon boundary

Figure 6 Inhibition of adenylyl cyclase in AV12 cells expressing either the C17T or prototype receptor Adenylyl cyclase in intact cells was maximally stimulated with forskohn, and inhibition of cAMP production was determined in triplicate at the indicated concentration of β-endoφhm (A) or leu-enkephahn (B) Data are normalized to allow ready comparison of the IC50 values (the maximum inhibition is defined as 0 and the cyclase activity in the absence of agonist is defined as 1 ) The actual value for maximum inhibition ranged from 77 % to 95 %

DETAILED DESCRIPTION OF THE INVENTION As explained above, the present invention is based upon Applicants' suφπsing and unexpected discovery of heretofore unknown single nucleotide polymoφhisms (SNPs) m the human mu opioid receptor, along with combinations thereof Furthermore, Applicants have discovered that more than one SNP can be present in either or both alleles of the human mu opioid receptor gene in a subject

In addition, the present invention is based upon Applicants' suφπsing discovery of molecules of heretofore unknown isolated nucleic acid molecules which encode human mu opioid receptors, wherein the DNA sequences include a combination of presently known polymoφhisms and subsequently of the human mu opioid receptors discovered by Applicants and set forth herein

Furthermore, the present invention is based upon Applicants' surprising and unexpected discovery that the expression of variant alleles of the human mu opioid gene comprising a DNA sequence having a variation in SEQ ID NO 1 , wherein the variations comprise A118G or C17T, produce a variant mu opioid receptor comprising an amino acid sequence having a variation in SEQ ID NO.2, wherein the variations comprise Asn40Asp or AlaόVal, and that these variant receptors exhibit a binding affinity for β-endoφhin that is different from tt\e binding affinity of a mu opioid receptor comprising an amino acid sequence of SEQ ID NO 2, and is encoded by the predominant or "most common" allele of the mu opioid receptor gene comprising a DNA sequence ot SEQ ID NO 1

Furthermore, the present invention is based upon Applicants' prediction that variant alleles of the mu opioid receptor gene, which comprise a DNA sequence having a variation m SEQ ID NO 1 , wherein the variation comprises A118G or C17T encode variant mu opioid receptors comprising amino acid sequence having a variation in SEQ ID NO 2 wherein the variation comprises Asn40Asp or AlaόVal, and the variant receptors have an activity in vivo different from the of the predominant or ' most common" mu opioid receptor, the presence of such variant alleles in a bodily sample from a subject is expected to be indicative of the activity of the mu opioid receptors in the subject

The present invention further extends to heretofore unknown polymoφhisms of the human mu opioid receptor gene that can serve as genetic markers to map the locus of the human mu opioid receptor gene

Moreover, the present invention extends to the characterization of the binding properties of human mu opioid receptors produced from the expression of nucleic acid molecules comprising DNA sequences with such heretofore unknown polymoφhisms of the human mu opioid receptor gene, or combinations of heretofore unknown polymoφhisms and known polymoφhisms In particular, the human mu opioid receptor is the major pharmacological target for clinically important opioid alkaloids, including moφhme, methadone and fentanyl, as well as for endogenous opioid peptides such as β-endoφhin, Met- enkephahn-Arg-Phe, the recently identified endomoφhins [Zadma, J E., Hackler, L , Ge, L J & Kastin, A J. (1997) Nature 386, 499-502, which is hereby incoφorated by reference in its entirety] and other opioid drugs [Pasternak, G W (1993) Clin.Neuropharmacol 16, 1-18, which is hereby incoφorated by reference herein in its entirety] Applicants have discovered that, suφπsingly, human β-endoφhin, an endogenous opioid, has a much higher binding affinity for a human mu opioid receptor produced from expression of the Al 18G variant allele of the human mu opioid receptor gene than for a human mu opioid receptor protein produced from the expression of the predominant or "most common" allele of the human mu opioid receptor gene (SEQ ID NO 1) comprising a DNA sequence of SEQ ID NO 1 , and th£t a variant receptor encoded by a variant allele comprising a DNA sequence of SEQ ID NO 1, wherein the variation comprises A118G has increased activity relative to the predominant or 'most common" allele This increased activity is expected to result m lower activity of the HPA and HPG axes As a result sexual and reproductive functions, gastrointestinal motihty, immune response and/or ability to withstand stress are increased in the subject relative to the levels of such functions in a standard comprising two alleles of the mu opioid receptor gene comprising a DNA sequence of SEQ ID NO 1

In contrast, a human mu opioid receptor produced from expression of the C17T variant allele of the human mu opioid receptor gene has decreased binding affinity for β-endoφhm relative to the binding affinity of a human mu opioid receptor protein produced from the expression of the predominant or ' most common' allele of the human mu opioid receptor gene (SEQ ID NO 1) comprising a DNA sequence of SEQ ID NO 1 Consequently, a variant receptor encoded by a C17T variant allele exhibits decreased activity relative to the predominant or "most common" allele This decreased activity is expected to result in increased activity of HPA and HPG axes Hence, sexual and reproductive functions, gastrointestinal motihty, immune response and/or ability to withstand stress are decreased m the subject relative to the levels of such physiological functions in a standard comprising two alleles of the mu opioid receptor gene comprising a DNA sequence of SEQ ID NO 1

Furthermore, the present invention extends to characterizing the activity of such heretofore unknown human mu opioid receptors produced from the expression of isolated nucleic acid molecules of the present invention More particularly, the increased or decreased ability of such human mu opioid receptors produced from isolated nucleic acid acids of the present invention to activate G protein-activated inwardly rectifying K⁺ (GIRK) channels via a G protem-mediated mechanism can be determined, and is expected to be indicative of activity

The present invention further extends to Applicants' discovery that polymoφhisms such as Al 18G and C17T, are present in the population at a high frequency (greater than 5 %), and that the presence of such polymoφhisms in the human mu opioid receptor gene of a subject correlates to an increased or decreased susceptibility to addictive diseases, such as heroin addiction, cocaine addiction, or alcohol addiction, to name only a few, and are expected to modulate physiological functions regulated by the HPA and HPG axes, such as sexual and reproductive functions, gastrointestinal motihty, immune response and/or ability to withstand stress, relative to such functions in a standard

The present invention extends to diagnostic methods to determine a subject's increased or decreased susceptibility to at least one addictive disease With the results of such methods, targeted prevention methods, early therapeutic intervention, and improved chronic treatment to opioid addiction are set forth herein and encompassed by the present invention In addition, attending medical professionals of subjects armed with the results of such diagnostic methods can determine whether administration of opioid analgesics is appropπate or whether non-opioid derived analgesics should be administered to the subject Also, appropriate choice and type of analgesic can be made in treating a subject s pain

Also, the present invention extends to methods of determining a subject's increased or decreased susceptibility to pain and response to analgesics, and using that information when prescribing analgesics to the subject

Furthermore, the present invention extends to diagnosing a disease or disorder related to a physiological function regulated by the HPA and HPG axes, such as sexual and reproductive functions, gastrointestinal motility, immune response, and the ability to withstand stress

The present invention further extends to variant alleles of the human mu opioid receptor gene comprising a DNA sequence comprising a heretofore unknown polymoφhism, such as G24A,

G779A, or

G942A, or combinations thereof

Furthermore, Applicants' invention extends to variant alleles of the human mu opioid receptor gene comprising a DNA sequence having at least two variations in the predominant or "most common" allele comprising a human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO 1. wherein the variations comprise A118G,

C17T,

G24A,

G779A, or

G942A, or a combination thereof

Furthermore, the present invention is based on Applicants' discovery that suφπsmgly and unexpectedly, the C17T vaπant allele of the human mu opioid receptor is present in a statistically significantly higher frequency in opioid dependent persons than in persons not addicted to opioids In contrast, within an Hispanic study subject group, it was found that the A118G variant allele was present in a significantly higher proportion of non-opioid- dependent subjects compared with the opioid-dependent subjects [Yates-corrected Chi- square χ2 = 8 22 (P = 0 0041)] This finding suggests the possibility that the A118G SNP confers a relative protection against opioid dependence

Consequently, an initial aspect of the present invention involves isolation of heretofore unknown variant alleles of the human mu opioid receptor gene As used herein, the term "gene" refers to an assembly of nucleotides that encode a polypeptide, and includes cDNA and genomic DNA nucleic acids

Furthermore, in accordance with the present invention there may be employed conventional molecular biology, microbiology, and recombinant DNA techniques within the skill of the art Such techniques are explained fully in the literature See, e g , Sambrook, Fπtsch & Maniatis, Molecular Cloning A Laboratory Manual, Second Edition (1989) Cold Spring Harbor Laboratory Press, Cold Spring Harbor, New York (herein "Sambrook et al , 1989"), DNA Cloning A Practical Approach, Volumes I and II (D N Glover ed 1985), Oligonucleotide Synthesis (M J Gait ed 1984), Nucleic Acid Hybridization [B D Hames & S J Higgins eds (1985)], Transcription And Translation [B D Hames & S J Higgins, eds (1984)], Animal Cell Culture [R I Freshney, ed (1986)], Immobilized Cells And Enzymes [IRL Press, (1986)], B Perbal, A Practical Guide To Molecular Cloning (1984), F M Ausubel et al (eds ), Current Protocols in Molecular Biology, John Wiley & Sons, Inc (1994)

Therefore, if appearing herein, the following terms shall have the definitions set out below

A vector' is a replicon such as plasmid, phage or cosmid, to which another DNA segment may be attached so as to bring about the replication of the attached segment A 'replicon" is any genetic element (e g , plasmid, chromosome, virus) that functions as an autonomous unit of DNA replication in vivo, i e , capable of replication under its own control

A cassette refers to a segment of DNA that can be inserted into a vector at specific restriction sites The segment of DNA encodes a polypeptide of interest, and the cassette and restriction sites are designed to ensure insertion of the cassette in the proper reading frame for transcription and translation

A cell has been transfected" bv exogenous or heterologous DNA when such DNA has been introduced inside the cell A cell has been transformed" by exogenous or heterologous DNA when the transfected DNA effects a phenotypic change Preferably, the transforming DNA should be integrated (covalently linked) into chromosomal DNA making up the genome of the cell

"Heterologous ' DNA refers to DNA not naturally located in the cell, or in a chromosomal site of the cell Preferably, the heterologous DNA includes a gene foreign to the cell

A ' nucleic acid molecule" refers to the phosphate ester polymeric form of πbonucleosides (adenosme, guanosine, undine or cytidme, 'RNA molecules") or deoxyπbonucleosides (deoxyadenosine, deoxyguanosine, deoxythymidme, or deoxycytidme, "DNA molecules"), or any phosphoester analogs thereof, such as phosphorothioates and thioesters, in either single stranded form, or a double-stranded helix Double stranded DNA-DNA, DNA-RNA and RNA-RNA helices are possible The term nucleic acid molecule, and in particular DNA or RNA molecule, refers only to the primary and secondary structure of the molecule, and does not limit it to any particular tertiary forms Thus, this term includes double- stranded DNA found, inter alia, m linear or circular DNA molecules (e g , restriction fragments), plasmids, and chromosomes In discussing the structure of particular double- stranded DNA molecules, sequences may be described herein according to the normal convention of giving only the sequence in the 5 to 3' direction along the nontranscribed strand of DNA (i e , the strand having a sequence homologous to the mRNA) A "recombinant DNA molecule is a DNA molecule that has undergone a molecular biological manipulation

A nucleic acid molecule is "hybridizable" to another nucleic acid molecule, such as a cDNA, genomic DNA, or RNA, when a single stranded form of the nucleic acid molecule can anneal to the other nucleic acid molecule under the appropriate conditions of temperature and solution ionic strength (see Sambrook et al , supra) The conditions of temperature and ionic strength determine the "stringency" of the hybridization For preliminary screening for homologous nucleic acids, low stringency hybridization conditions, corresponding to a T_m of 55° , can be used, e g , 5x SSC, 0 1 % SDS, 0 25 % milk, and no formamide, or 30% formamide, 5x SSC 0 5 % SDS) Moderate stringency hybridization conditions correspond to a higher T_m, e g 40% formamide, with 5x or 6x SSC High stringency hybridization conditions correspond to the highest T„„ e g . 50% formamide, 5x or 6x SSC Hybridization requires that the two nucleic acids contain complementary sequences, although depending on the stringency of the hybridization, mismatches between bases are possible The appropriate stringency for hybridizing nucleic acids depends on the length of the nucleic acids and the degree of complementation, variables well known m the art The greater the degree of similarity or homology between two nucleotide sequences, the greater the value of T_ra for hybrids of nucleic acids having those sequences The relative stability (corresponding to higher T_m) of nucleic acid hybridizations decreases in the following order RNA RNA, DNA RNA, DNA DNA For hybrids of greater than 100 nucleotides in length, equations for calculating T_m have been derived (see Sambrook et al , supra, 9.50-0.51). For hybridization with shorter nucleic acids, i.e. , oligonucleotides, the position of mismatches becomes more important, and the length of the oligonucleotide determines its specificity (see Sambrook et al., supra, 11.7-11.8). Preferably a minimum length for a hybridizable nucleic acid is at least about 10 nucleotides; preferably at least about 20 nucleotides; and more preferably the length is at least about 30 nucleotides; and most preferably 40 nucleotides.

In a specific embodiment, the term "standard hybridization conditions" refers to a T_m of 55 °C, and utilizes conditions as set forth above. In a preferred embodiment, the T_m is 60^DC; in a more referred embodiment, the T_m is 65°C.

"Homologous recombination" refers to the insertion of a foreign DNA sequence of a vector in a chromosome Preferably, the vector targets a specific chromosomal site for homologous recombination. For specific homologous recombination, the vector will contain sufficiently long regions of homology to sequences of the chromosome to allow complementary binding and incorporation of the vector into the chromosome. Longer regions of homology, and greater degrees of sequence similarity, may increase the efficiency of homologous recombination.

A DNA "coding sequence" is a double-stranded DNA sequence which is transcribed and translated into a polypeptide in a cell in vitro or in vivo when placed under the control of appropriate regulatory sequences. The boundaries of the coding sequence are determined by a start codon at the 5' (amino) terminus and a translation stop codon at the 3' (carboxyl) terminus. A coding sequence can include, but is not limited to, prokaryotic sequences, cDNA from eukaryotic mRNA, genomic DNA sequences from eukaryotic (e.g. , mammalian) DNA, and even synthetic DNA sequences. If the coding sequence is intended for expression in a eukaryotic cell, a polyadenylation signal and transcription termination sequence will usually be located 3' to the coding sequence.

Transcriptional and translational control sequences are DNA regulatory sequences, such as promoters, enhancers, terminators, and the like, that provide for the expression of a coding sequence in a host cell. In eukaryotic cells, polyadenylation signals are control sequences. A "promoter sequence" or "promoter" is a DNA regulatory region capable of binding RNA polymerase in a cell and initiating transcription of a downstream (3 ' direction) coding sequence For puφoses of defining the present invention, the promoter sequence is bounded at its 3' terminus by the transcription initiation site and extends upstream (5' direction) to include the minimum number of bases or elements necessary to initiate transcription at levels detectable above background Within the promoter sequence will be found a transcription initiation site (conveniently defined for example, by mapping with nuclease SI), as well as protein binding domains (consensus sequences) responsible for the binding of RNA polymerase

A coding sequence is under the control' of transcπptional and translational control sequences in a cell when RNA polymerase transcribes the coding sequence into mRNA, which is then trans-RNA spliced and translated into the protein encoded by the coding sequence

A coding sequence is operatively associated with" a transcriptional and translational control sequences, such as a promoter for example, when RNA polymerase transcribes the coding sequence into mRNA, which in turn is translated into a protein encoding by the coding sequence

A "signal sequence ' is included at the beginning of the coding sequence of a protein to be expressed on the surface of a cell This sequence encodes a signal peptide, N-terminal to the mature polypeptide, that directs the host cell to translocate the polypeptide The term "translocation signal sequence" is used herein to refer to this sort of signal sequence Translocation signal sequences can be found associated with a variety of proteins native to eukaryotes and prokaryotes, and are often functional in both types of organisms

An "expression control sequence" is a DNA sequence that controls and regulates the transcription and translation of another DNA sequence A coding sequence is "under the control" of transcriptional and translational control sequences in a cell when RNA polymerase transcribes the coding sequence into mRNA, which is then translated into the protein encoded by the coding sequence The term "primer" as used herein refers to an oligonucleotide, whether occurring naturally as in a purified restriction digest or produced synthetically, which is capable of acting as a point of initiation of synthesis when placed under conditions in which synthesis of a primer extension product, which is complementary to a nucleic acid strand, is induced, 1 e , in the presence of nucleotides and an inducing agent such as a DNA polymerase and at a suitable temperature and pH The primer may be either single-stranded or double-stranded and must be sufficiently long to prime the synthesis of the desired extension product in the presence of the inducing agent The exact length of the primer will depend upon many factors, including temperature, source of primer and use of the method For example, for diagnostic applications, depending on the complexity of the target sequence, the oligonucleotide primer typically contains 15-25 or more nucleotides, although it may contain fewer nucleotides

The primers herein are selected to be ' substantially' complementary to different strands of a particular target DNA sequence This means that the primers must be sufficiently complementary to hybridize with their respective strands Therefore, the primer sequence need not reflect the exact sequence of the template For example, a non-complementary nucleotide fragment may be attached to the 5' end of the primer, with the remainder of the primer sequence being complementary to the strand Alternatively, non-complementary bases or longer sequences can be interspersed into the primer, provided that the primer sequence has sufficient complementarity with the sequence of the strand to hybridize therewith and thereby form the template for the synthesis of the extension product

A cell has been ' transformed" by exogenous or heterologous DNA when such DNA has been introduced inside the cell The transforming DNA may or may not be integrated (covalently linked) into chromosomal DNA making up the genome of the cell In prokaryotes, yeast, and mammalian cells for example, the transforming DNA may be maintained on an episomal element such as a plasmid With respect to eukaryotic cells, a stably transformed cell is one m which the transforming DNA has become integrated into a chromosome so that it is inlierited by daughter cells through chromosome replication This stability is demonstrated by the ability of the eukaryotic cell to establish cell lines or clones comprised of a population of daughter cells containing the transforming DNA A "clone" is a population of cells derived from a single cell or common ancestor by mitosis A "cell line" is a clone of a primary cell that is capable of stable growth in vitro for many generations

The phrase "expected to be indicative" is used herein to refer to the correlation between the identity of the allelic vaπatιon(s) in an individual and the susceptibility of an individual to addictive disease, sensitivity to pam and analgesics, therapeutic effectiveness of analgesics, and other physiological manifestations described herein related to the function of the mu opioid receptor, such as but not limited to the responsiveness to stress, peripheral gastrointestinal function, immune function, and reproductive biology The correlations are based on the findings in the present invention of the relationship between the biochemistry and cellular function of the variants of the mu opioid receptor and clinical observations, analyzed statistically, on history of drug dependence, reproductive function, gastrointestinal function, response to stress, and other previous or current conditions Expected correlations of mu opioid receptor alleles and susceptibility to various conditions may be increased susceptibility or decreased susceptibility

As explained above, within the scope of the present invention are DNA sequences encoding variant alleles of a human mu opioid receptor gene of the present invention, which comprise at least one variation in the predominant or 'most common" allele of the human mu opioid receptor gene The most common allele comprises a DNA sequence of SEQ ID NO 1, and variations in the most common allele comprise

G24A, G779A, or G942A, or combinations thereof

In another embodiment, the present invention comprises DNA sequences encoding variant alleles of a human mu opioid receptor gene, comprising at least two variations in the predominant or "most common" allele of the human mu opioid receptor gene, wherein the most common human mu opioid receptor gene comprises a DNA sequence of SEQ ID NO 1 Variant alleles of the human mu opioid receptor gene encompassed by the present invention comprise a DNA sequence comprising at least two variations of SEQ ID NO 1 , wherein the variation comprises G24A, G779A, G942A, A118G, or

C17T

Moreover, due to degenerate nature of codons in the genetic code, variant human mu opioid receptor proteins encoded by variant alleles of the present invention, wherein the variant human mu opioid receptors comprise an ammo acid sequence having at least one variation in SEQ ID NO 2, wherein the variations comprise Asn40Asp or conserved variants thereof, AlaόVal or conserved variants thereof, or Arg260Hιs or conserved variants thereof, or combinations thereof, can be encoded by nucleic acid molecules other than those set forth above "Degenerate nature" refers to the use of different three-letter codons to specify a particular amino acid pursuant to the genetic code It is well known in the art that the following codons can be used interchangeably to code for each specific amino acid

Phenylalamne (Phe or F) UUU or UUC

Leucme (Leu or L) UUA or UUG or CUU or CUC or CUA or CUG

Isoleucme (He or I) AUU or AUC or AUA

Methiomne (Met or M) AUG

Vahne (Val or V) GUU or GUC of GUA or GUG Seπne (Ser or S) UCU or UCC or UCA or UCG or AGU or AGC

Proline (Pro or P) CCU or CCC or CCA or CCG

Threomne (Thr or T) ACU or ACC or ACA or ACG

Alanme (Ala or A) GCU or GCG or GCA or GCG

Tyrosme (Tyr or Y) UAU or UAC Histidine (His or H) CAU or CAC

Glutamine (Gin or Q) CAA or CAG

Asparagme (Asn or N) AAU or AAC

Lysme (Lys or K) AAA or AAG Aspartic Acid (Asp or D) GAU or GAC

Glutamic Acid (Glu or E) GAA or GAG

Cysteine (Cys or C) UGU or UGC

Arginme (Arg or R) CGU or CGC or CGA or CGG or AGA or AGG Gfycme (Gly or G) GGU or GGC or GGA or GGG Tryptophan (Tφ or W) UGG

Termination codon UAA (ochre) or UAG (amber) or UGA (opal)

It should be understood that the codons specified above are for RNA sequences The corresponding CQdons for DNA have a T substituted for U

As used herein, the term "sequence homology" in all its grammatical forms refers to the relationship between proteins that possess a common evolutionary origin," including proteins from superfamihes (e g , the lmmunoglobulin superfamily) and homologous proteins from different species (e g , myosin light chain etc ) (Reeck et al , 1987, Cell 50 667)

Accordingly, the term "sequence similarity ' in all its grammatical forms refers to the degree of identity or correspondence between nucleic acid or ammo acid sequences of proteins that do not share a common evolutionary origin (see Reeck et al , supra)

However, in common usage and in the instant application, the term "homologous, " when modified with an adverb such as "highly, " may refer to sequence similarity and not a common evolutionary origin

In a specific embodiment, two DNA sequences are "substantially homologous" or "substantially similar" when at least about 50% (preferably at least about 75%, and most preferably at least about 90 or 95 %) of the nucleotides match over the defined length of the DNA sequences Sequences that are substantially homologous can be identified by comparing the sequences using standard software available in sequence data banks, or in a Southern hybridization experiment under, for example, stringent conditions as defined for that particular system Defining appropriate hybridization conditions is withm the skill of the art See, e g , Maniatis et al , supra, DNA Cloning, Vols I & II, supra, Nucleic Acid Hybridization, supra Similarly, m a particular embodiment, two ammo acid sequences are "substantially homologous" or "substantially similar" when greater than 30% of the ammo acids are identical, or greater than about 60% are similar (functionally identical) Preferably, the similar or homologous sequences are identified by alignment using, for example, the GCG (Genetics Computer Group, Program Manual for the GCG Package, Version 7, Madison, Wisconsin) pileup program

The term "corresponding to" is used herein to refer to similar or homologous sequences, whether the exact position is identical or different from the molecule to which the similarity or homology is measured Thus, the term 'corresponding to" refers to the sequence similarity, and not the numbering of the amino acid residues or nucleotide bases

A variant allele of the human mu opioid receptor gene of the present invention, whether genomic DNA or cDNA, can be isolated from any source, particularly from a human cDNA or genomic library Methods for obtaining an allele of a human mu opioid receptor gene, variants thereof, or the most common, are well known in the art, as described above (see, e g , Sambrook et al , 1989, supra)

Accordingly , any human cell potentially can serve as the nucleic acid source for the molecular cloning of a variant allele of the human mu opioid receptor gene of the present invention, or a nucleic acid molecule hybridizable to a variant allele of a human mu opioid receptor gene of the present invention The DNA may be obtained by standard procedures known in the art from cloned DNA (e g , a DNA "library") and preferably is obtained from a cDNA library prepared from tissues with high level expression of a human mu opioid receptor protein, by chemical synthesis, by cDNA cloning, or by the cloning of genomic DNA, or fragments thereof, purified from the desired cell (See, for example, Sambrook et al , 1989, supra, Glover, D M (ed ), 1985, DNA Cloning A Practical Approach, MRL Press, Ltd , Oxford, U K Vol I, II) Clones derived from genomic DNA may contain regulatory and intron DNA regions in addition to coding regions, clones derived from cDNA will not contain tron sequences Whatever the source, an allele of a human mu opioid receptor gene of the present invention should be molecularly cloned into a suitable vector for propagation In the molecular cloning of a human mu opioid receptor gene of the present invention, DNA fragments are generated, some of which will encode an allele The DNA may be cleaved at specific sites using various restriction enzymes Alternatively, one may use DNAse in the presence of manganese to fragment the DNA, or the DNA can be physically sheared, as for example, by somcation The linear DNA fragments can then be separated according to size by standard techniques, including but not limited to, agarose and polyacrylamide gel electrophoresis and column chromatography

Once the DNA fragments are generated, identification of the specific DNA fragment containing an allele of a human mu opioid receptor of the present invention may be accomplished in a number of ways For example, if an amount of a portion of an allele of a human mu opioid receptor gene, or its specific RNA, or a fragment thereof, is available and can be purified and labeled, the generated DNA fragments may be screened by nucleic acid hybridization to the labeled probe (Benton and Davis, 1977, Science 196 180, Grunstein and Hogness. 1975, Proc Natl Acad Sci U S A 72 3961) For example, a set of oligonucleotides corresponding to the partial amino acid sequence information obtained for a human mu opioid receptor protein can be prepared and used as probes for DNA encoding a variant allele of a human mu opioid receptor gene of the present invention, as was done in a specific example, infra, or as primers for cDNA or mRNA (e g , in combination with a poly-T primer for RT-PCR) Preferably, a fragment is selected that is highly unique to a variant allele of the human mu opioid receptor gene of the invention Those DNA fragments with substantial homology to the probe will hybridize As noted above the greater the degree of homology, the more stringent hybridization conditions can be used

Further selection can be carried out on the basis of the properties of an allele of a human mu opioid receptor gene of the present invention e g , if the allele encodes a variant human mu opioid receptor protein having an lsoelectπc, electrophoretic, ammo acid composition, or partial amino acid sequence different from that produced from the expression of the most common allele of a human mu opioid receptor gene (SEQ ID NO 1) herein Thus, the presence of an allele ot a human mu opioid receptor gene of the present invention may be detected by assays based on the physical, chemical, or immunological properties of its expressed product For example, cDNA clones, or DNA clones which hybrid-select the proper mRNAs, can be selected which produce a protein that, e g , has different electro- phoretic migration, lsoelectπc focusing or non-equilibrium pH gel electrophoresis behavior, proteolytic digestion maps, or antigenic properties as known for a human mu opioid receptor produced from expression of a most common allele of the human mu opioid receptor gene (SEQ ID NO 1)

An allele of a human mu opioid receptor gene of the present invention can also be identified by mRNA selection, i e , by nucleic acid hybridization followed by in vitro translation In this procedure, nucleotide fragments are used to isolate complementary mRNAs by hybridization Siich DNA fragments may represent available, purified DNA of an allele of a human mu opioid receptor gene of the present invention, or may be synthetic oligonucleotides designed from the partial amino acid sequence information Immunoprecipitation analysis or functional assays of the in vitro translation products of the products of the isolated mRNAs identifies the mRNA and, therefore, the complementary DNA fragments, that contain the desired sequences

A labeled cDNA of an alleie of a human mu opioid receptor gene of the present invention, or fragments thereof, or a nucleic acid hybridizable under standard hybridization conditions to an allele of a human mu opioid receptor gene of the present invention, can be synthesized using sequences set forth herein The radiolabeled mRNA or cDNA may then be used as a probe to identify homologous DNA fragments from among other genomic DNA fragments Suitable labels include enzymes, radioactive isotopes, fluorophores (e g , fluorescene isothiocyanate (FITC), phycoerythrm (PE) Texas red (TR), rhodamine, free or chelated lanthamde series salts especially Eu^J , to name a few fluorophores), chromophores, radioisotopes, chelating agents, dyes, colloidal gold, latex particles, ligands (e g , biotin), and chemiluminescent agents When a control marker is employed, the same or different labels may be used for the receptor and control marker

In the instance where a radioactive label, such as the isotopes ³H, ¹ C, ³²P, ³⁵S, ³⁶C1, ⁵¹Cr, ⁵⁷Co, ⁵⁸Co, ⁵⁹Fe, ⁹⁰Y, ¹²⁵I, ¹³¹I, and ^l85Re are used, known currently available counting procedures may be utilized In the instance where the label is an enzyme, detection may be accomplished by any of the presently utilized coloπmetπc, spectrophotometπc, fluorospectrophotometπc, amperometπc or gasometπc techniques known in the art Direct labels are one example of labels which can be used according to the present invention A direct label has been defined as an entity, which in its natural state, is readily visible, either to the naked eye, or with the aid of an optical filter and/or applied stimulation, e g , U V light to promote fluorescence Among examples of colored labels, which can be used according to the present invention, include metallic sol particles, for example, gold sol particles such as those described by Leuveπng (U S Patent 4,313,734), dye sol particles such as described by Gπbnau et al (U S Patent 4,373,932) and May et al (WO 88/08534), dyed latex such as described by May, supra, Snyder (EP-a 0 280 559 and 0 281 327), or dyes encapsulated m hposomes as described by Campbell et al (U S Patent 4,703,017) Other direct labels include a radionucleotide, a fluorescent moiety or a luminescent moiety In addition to these direct labeling devices, indirect labels comprising enzymes can also be used according to the present invention Various types of enzyme linked immunoassays are well known in the art, for example, alkaline phosphatase and horseradish peroxidase, lysozyme, glucose-6-phosphate dehydrogenase, lactate dehydrogenase, urease, these and others have been discussed in detail by Eva Engvall in Enzyme Immunoassay ELISA and EMIT in Methods in Enzymology, 70 419-439, 1980 and in U S Patent 4,857,453

Other labels for use in the invention include magnetic beads or magnetic resonance imaging labels

Cloning Vectors The present invention also relates to cloning vectors comprising variant alleles of a human mu opioid receptor gene of the present invention, and an origin of replication For puφoses of this Application, an "origin of replication refers to those DNA sequences that participate in DNA synthesis

As explained above, in an embodiment of the present invention, variant alleles of a human mu opioid receptor gene of the present invention comprise a DNA sequence having at least one variation in the most common allele of a human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO 1 , wherein the variation comprises

G24A,

G779A, or G942A, or combinations thereof

In another embodiment, the present invention extends to variant alleles of a human mu opioid receptor gene, comprising a DNA sequence having at least two variations in the DNA sequence of SEQ ID NO 1, wherein the variations comprise G24A, G779A, G942A, A118G, or

C17T

Furthermore, an isolated variant allele of a human mu opioid receptor gene of the present invention, or isolated nucleic acid molecules hybridizable under standard hybridization conditions to an isolated variant allele of a human mu opioid receptor gene of the present invention, can be inserted into an appropπate cloning vector m order to produce multiple copies of the variant allele or isolated nucleic acid molecule A large number of vector-host systems known in the art may be used Possible vectors include, but are not limited to, plasmids or modified viruses The vector system used however must be compatible with the host cell used Examples of vectors include having applications herein, but are not limited to E coli, bacteriophages such as lambda derivatives, or plasmids such as pBR322 derivatives or pUC plasmid derivatives, e g , pGEX vectors, pmal-c, pFLAG, etc The insertion into a cloning vector can, for example, be accomplished by hgating a vaπant allele of the human mu opioid receptor gene of the present invention, or an isolated nucleic acid hybridizable thereto under standard hybridization conditions, into a cloning vector which has complementary cohesive termini However, if the complementary restriction sites used to fragment the variant allele or isolated nucleic acid hybridizable thereto are not present in the cloning vector, the ends of the variant allele or the isolated nucleic acid molecule hybridizable thereto under standard hybridization conditions may be enzymatically modi- fied Alternatively, any site desired may be produced by hgatmg nucleotide sequences (linkers) onto the DNA termini, these ligated linkers may comprise specific chemically synthesized oligonucleotides encoding restriction endonuclease recognition sequences Such recombinant molecules can then be introduced into host cells via transformation, transfection, infection, electroporation, etc , so that many copies of a variant allele of a human mu opioid receptor gene of the present invention, or an isolated nucleic acid molecule hybridizable thereto under standard hybridization conditions, can be generated Preferably, the cloned isolated variant is contained on a shuttle vector plasmid, which provides for expansion in a cloning cell, e g , E coli, and facile purification for subsequent insertion into an appropriate expression cell line, if such is desired For example, a shuttle vector, which is a vector that can replicate m more than one type of organism, can be prepared for replication in both E coli and Saccharomyces cerevisiae by linking sequences from an E coli plasmid with sequences from the yeast 2μ plasmid

In an alternative method an isolated variant allele of a human mu opioid receptor gene of the present invention or an isolated nucleic acid molecule hybridizable thereto under standard hybridization conditions may be identified and isolated after insertion into a suitable cloning vector in a "shot gun" approach Enrichment for a variant allele, for example, by size fractionation, can be done before insertion into the cloning vector

Expression Vectors As stated above, the present invention extends to an isolated variant allele of a human mu opioid receptor gene, comprising a DNA sequence having at least one variation in the DNA sequence of the predominant or "most common' allele of the human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO 1 wherein the variations comprise G24A, G779A, or G942A, or combinations thereof

In another embodiment, the present invention extends to an isolated vaπant allele of a human mu opioid receptor gene, a DNA sequence having at least two variations m the predominant or "most common" allele of the human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO 1 wherein the variations comprise

G24A,

G779A,

G942A, A118G, or C17T

Variant alleles of the present invention, along with isolated nucleic acid molecules hybridizable to such variant alleles under standard hybridization conditions, can be inserted into an appropriate expression vector, i e , a. vector which contains the necessary elements for the transcription and translation of the inserted protein-coding sequence Thus, a variant allele of the present invention, or an isolated nucleic acid molecule hybridizable to a variant allele of the present invention under standard hybridization conditions, is operatively associated with a promoter in an expression vector of the invention A DNA sequence is 'operatively associated" to an expression control sequence, such as a promoter, when the expression control sequence controls and regulates the transcription and translation of that DNA sequence The term "operatively associated" includes having an appropriate start signal (e g , ATG) in front of the DNA sequence to be expressed and maintaining the correct reading frame to permit expression of the DNA sequence under the control of the expression control sequence and production of the desired product encoded by the DNA sequence If a variant allele of the present invention, or an isolated nucleic acid hybridizable thereto under standard hybridization conditions does not contain an appropriate start signal, such a start signal can be inserted into the expression vector in front of (5' of) the molecule

Both cDNA and genomic sequences can be cloned and expressed under control of such regulatory sequences An expression vector also preferably includes a replication origin

The necessary transcriptional and translational signals can be provided on a recombinant expression vector, or they may be supplied by an allele comprising a human mu opioid receptor gene

Potential host-vector systems include but are not limited to mammalian cell systems infected with virus (e g , vaccinia virus, adenovirus, etc ), insect cell systems infected with virus (e g , baculovirus), microorganisms such as yeast containing yeast vectors, or bacteria transformed with bacteriophage, DNA, plasmid DNA, or cosmid DNA The expression elements of vectors vary in their strengths and specificities Depending on the host-vector system utilized, any one of a number of suitable transcription and translation elements may be used

A variant allele of a human mu opioid receptor gene of the present invention or an isolated nucleic acid molecule hybridizable thereto under standard hybridization conditions may be expressed chromosomally, after integration of the coding sequence by recombination In this regard, any of a number of amplification systems may be used to achieve high levels of stable gene expression (See Sambrook et al , 1989, supra)

A unicellular host transformed or transfected with an expression vector of the present invention is cultured in an appropriate cell culture medium that provides for expression by the unicellular host of the variant allele, or isolated nucleic acid hybridizable thereto under standard hybridization conditions

Any of the methods previously described for the insertion of DNA fragments into a cloning vector may be used to construct expression vectors of the present invention These methods may include in vitro recombinant DNA and synthetic techniques and in vivo recombination (genetic recombination)

Expression of a variant allele of a human mu opioid receptor gene of the present invention or an isolated nucleic acid molecule hybridizable to a variant allele of a human mu opioid receptor gene under standard hybridization conditions, may be controlled by any promoter/enhancer element known in the art, but these regulatory elements must be functional in the host selected for expression Promoters which may be used to control expression include, but are not limited to, the SV40 early promoter region (Benoist and Chambon, 1981 , Nature 290 304-310), the promoter contained in the 3' long terminal repeat of Rous sarcoma virus (Yamamoto, et al , 1980, Cell 22 787-797), the heφes thymidine kmase promoter (Wagner et al 1981, Proc Natl Acad Sci U S A 78 1441-1445), the regulatory sequences of the metallothionein gene (Bπnster et al , 1982, Nature 296 39-42), prokaryotic expression vectors such as the β-lactamase promoter (Villa-Kamaroff, et al , 1978, Proc Natl Acad Sci U S A 75 3727-3731), or the tac promoter (DeBoer, et al , 1983, Proc Natl Acad Sci U S A 80 21-25), see also "Useful proteins from recombinant bacteria" m Scientific American, 1980, 242 74-94, promoter elements from yeast or other fungi such as the Gal 4 promoter, the ADC (alcohol dehydrogenase) promoter, PGK (phosphoglycerol kmase) promoter, alkaline phosphatase promoter, and the animal transcriptional control regions, which exhibit tissue specificity and have been utilized in transgenic animals elastase I gene control region which is active m pancreatic acinar cells (Swift et al , 1984, Cell 38 639-646, Ornitz et al , 1986, Cold Spring Harbor Symp Quant Biol 50 399-409, MacDonald, 1987, Hepatology 7 425-515), msulm gene control region which is active in pancreatic beta cells (Hanahan, 1985, Nature 315 115-122), lmmunoglob- ulin gene control region which is active in lymphoid cells (Grosschedl et al , 1984, Cell 38 647-658, Adames et al , 1985, Nature 318 533-538, Alexander et al , 1987, Mol Cell Biol 7 1436-1444), mouse mammary tumor virus control region which is active in testicular, breast, lymphoid and mast cells (Leder et al , 1986, Cell 45 485-495), albumm gene control region which is active in liver (Pmkert et al , 1987, Genes and Devel 1 268- 276), alpha-fetoprotein gene control region which is active in liver (Krumlauf et al , 1985, Mol Cell Biol 5 1639-1648, Hammer et al , 1987, Science 235 53-58), alpha 1- antitrypsm gene control region which is active in the liver (Kelsey et al , 1987, Genes and Devel 1 161-171), beta-globin gene control region which is active in myeloid cells

(Mogram et al , 1985 Nature 315 338-340, Kolhas et al , 1986, Cell 46 89-94), myelin basic protein gene control region which is active in o godendrocyte cells in the bram (Readhead et al , 1987, Cell 48 703-712), myosin light chaιn-2 gene control region which is active in skeletal muscle (Sam, 1985, Nature 314 283-286), and gonadal releasing hormone gene control region which is active in the hypothalamus (Mason et al , 1986, Science 234 1372-1378)

Moreover, expression vectors comprising a variant allele of a human mu opioid receptor gene of the present invention, or an isolated nucleic acid molecule hybridizable thereto under standard hybridization conditions, can be identified by four general approaches (a) PCR amplification of the desired plasmid DNA or specific mRNA, (b) nucleic acid hybridization, (c) presence or absence of selection marker gene functions, and (d) expression of inserted sequences In the first approach, the variant allele or isolated nucleic acid molecule hybridizable thereto under standard hybridization conditions can be amplified by PCR to provide for detection of the amplified product In the second approach, the presence of a foreign gene inserted into an expression vector of the present invention can be detected by nucleic acid hybridization using probes comprising sequences that are homologous to an inserted marker gene In the third approach, the recombinant vector/host system can be identified and selected based upon the presence or absence of certain "selection marker" gene functions (e g , β-galactosidase activity, thymidine kinase activity, resistance to antibiotics, transformation phenotype, occlusion body formation in baculovirus, etc ) caused by the insertion of foreign genes in the vector In yet another example, if an isolated variant allele of a human mu opioid receptor gene of the present invention, or an isolated nucleic acid molecule hybridizable thereto under standard hybridization conditions, is inserted within the selection marker" gene sequence of the vector, recombinants containing the insert can be identified by the absence of the inserted gene function In the fourth approach, recombinant expression vectors can be identified by assaying for the activity, biochemical, or immunological characteristics of the gene product expressed by the recombinant, provided that the expressed protein assumes a functionally active conformation

Namrally, the present invention extends to a method of producing a vaπant human mu opioid receptor comprising an ammo acid sequence having at least one variation in the amino acid sequence ot SEQ ID NO 2, wherein the variation comprises Arg260Hιs or conserved variants thereof An example of such a method comprises the steps of culturing a unicellular host transformed or transfected with an expression vector comprising a variant allele of a human mu opioid receptor gene comprising a DNA sequence having a variation in SEQ ID NO 1, wherein the variation comprises G779A, wherein the variant allele which is operatively associated with a promoter The transformed or transfected unicellular host is then cultured under conditions that provide for expression of the variant allele of the human mu opioid receptor gene, and the expression product is recovered from the unicellular host

Another example involves culturing a unicellular host transformed or transfected with an isolated nucleic acid molecule hybridizable under standard hybridization conditions to a variant allele of a human mu opioid receptor gene comprising a DNA sequence having at least one variation in SEQ ID NO 1 , wherein the variation comprises G779A, wherein the isolated nucleic acid molecule is operatively associated with a promotor The variant human mu opioid receptor is then recovered from the host

In another embodiment, the present invention extends to a method for producing a vaπant human mu opioid receptor comprising an amino acid sequence having at least two variations in SEQ ID NO 2, wherein the variations comprise

Asn40Asp or conserved variants thereof,

AlaόVal or conserved variants thereof, or Arg260Hιs or conserved variants thereof,

Such a method comprises the steps of culturing a unicellular host transformed or transfected with an expression vector comprising a variant allele of a human mu opioid receptor gene of the present invention or an isolated nucleic acid molecule hybridizable thereto under standard hybridization conditions, and operatively associated with a promoter, that provides for expression of the variant allele or the isolated nucleic acid molecule hybridizable thereto under standard hybridization conditions After expression, a variant human mu opioid receptor of the present invention is recovered from the unicellular host

A wide variety of unicellular host/expression vector combinations may be employed in expressing the DNA sequences of this invention Useful expression vectors, for example, may consist of segments of chromosomal, non-chromosomal and synthetic DNA sequences Suitable vectors include derivatives of SV40 and known bacterial plasmids, e g , £ coli plasmids col El, pCRl, pBR322, pMal-C2, pET, pGEX (Smith et al , 1988, Gene 67 31- 40), pMB9 and their derivatives, plasmids such as RP4, phage DNAS, e g , the numerous derivatives of phage λ e g , NM989, and other phage DNA, e g , M13 and filamentous single stranded phage DNA, yeast plasmids such as the 2μ plasmid or derivatives thereof, vectors useful in eukaryotic cells, such as vectors useful in insect or mammalian cells, vectors derived from combinations of plasmids and phage DNAs, such as plasmids that have been modified to employ phage DNA or other expression control sequences, and the like

For example, in a baculovirus expression systems, both non-fusion transfer vectors, such as but not limited to pVL941 (BamWl cloning site, Summers), pVL1393 (BamΑl , Smal, Xbal, EcoRI, Notl, Xmalll, Bgtll, and Pstl cloning site, Invitrogen), pVL1392 (Bglϊ , Pstl, Notl, X αlll, EcoRI, Xbal, Smal, and BamΑl cloning site, Summers and Invitrogen), and pBlueβαcIII (BamΑl, BgUl, Pstl, Ncol, and Hindlll cloning site, with blue/white recombinant screening possible, Invitrogen), and fusion transfer vectors, such as but not limited to pAc700 (BamHl and Kpήl cloning site, in which the BamUl recognition site begins with the initiation codon, Summers), pAc701 and pAc702 (same as pAc700, with different reading frames), pAc360 (BamHl cloning site 36 base pairs downstream of a polyhedπn initiation codon, Invιtrogen(195)), and pBlueBacHisA, B, C (three different reading frames, with BamHl, Bglll, Pstl, Ncol, and Hindlϊl cloning site, an N-termmal peptide for ProBond purification, and blue/white recombinant screening of plaques, Invitrogen (220)) can be used

Mammalian expression vectors contemplated for use in the invention include vectors with inducible promoters, such as the dihydrofolate reductase (DHFR) promoter, e g , any expression vector with a DHFR expression vector, or a H R/methotrexate co-amplifica- tion vector, such as pED Pstl, SaH, Sbal, Smal, and EcoRI cloning site, with the vector expressing both the cloned gene and DHFR see Kaufman, Current Protocols in Molecular Biology, 16 12 (1991)

Alternatively, a glutamine synthetase/methionine sulfoximine co-amplification vector, such as pEE14 (Hindlll, Xbal, Smal, Sbal, EcoRI, and Bell cloning site, in which the vector expresses glutamine synthase and the cloned gene, Celltech) In another embodiment, a vector that directs episomal expression under control of Epstein Barr Virus (EBV) can be used, such as pREP4 (BamHl, Sfil, Xhol, Notl, Nhel, Hindlll, Nhel, Pvull, and Kpnl cloning site, constitutive RSV-LTR promoter, hygromycin selectable marker, Invitrogen), pCEP4 (BamHl , Sfil, Xhol, Notl, Nhel, Hindlll, Nhel Pvull, and Kpnl cloning site, constitutive hCMV immediate early gene, hygromycin selectable marker, Invitrogen), pMEP4 (Kpnl, Pvul, Nhel, Hindlll, Notl Xhol, Sfil BamHl cloning site, inducible methallothionein Ha gene promoter, hygromycin selectable marker Invitrogen), pREP8 (BamHl, Xhol, Notl, Hindlϊl, Nhel, and Kpnl cloning site, RSV-LTR promoter, histidinol selectable marker, Invitrogen), pREP9 (Kpnl, Nhel, Hindl l, Notl, Xhol, Sfil, and BamHl cloning site, RSV-LTR promoter, G418 selectable marker, Invitrogen), and pEBVHis (RSV-LTR promoter, hygromycin selectable marker, N-terminal peptide puπfiable via ProBond resm and cleaved by enterokmase, Invitrogen) Selectable mammalian expression vectors for use m the invention include pRc/CMV (H dIII, BstXl, Notl, Sbal, and Apal cloning site, G418 selection, Invitrogen), pRc/RSV (Hindlll, Spel, BstXl, Notl, Xbal cloning site, G418 selection, Invitrogen), and others Vaccinia virus mammalian expression vectors (see, Kaufman, 1991, supra) for use according to the invention include but are not limited to pSCl l (Smal cloning site, TK- and β-gal selection), pMJ601 (Sail, Smal, Afll, Narl, BspMll, BamHl, Apal, Nhel, Sacll, Kpnl, and Hindlϊl cloning site; TK- and β-gal selection), and pTKgptFIS (EcoRI, Pstl, Sail, Accl, Hindll, Sbal, BamHl, and Hpa cloning site, TK or XPRT selection).

Yeast expression systems can also be used according to the invention to produce a variant human mu opioid receptor or the present invention. For example, the non-fusion pYES2 vector (Xbal, Sphl, Shol, Notl, GstXl, EcoRI, BstXl, BamHl , Sad, Kpnl, and Hindlll cloning sit; Invitrogen) or the fusion pYESHisA, B, C (Xbal, Sphl, Shol, Notl, BstXl, EcoRI, BamHl, Sacl, Kpnl, and Hindlll cloning site, N-terminal peptide purified with ProBond resin and cleaved with enterokinase; Invitrogen), to mention just two, can be employed according to the invention.

Once a particular recombinant DNA molecule is identified and isolated, several methods known in the art may be used to propagate it. Once a suitable host system and growth conditions are established, recombinant expression vectors can be propagated and prepared in quantity. As previously explained, the expression vectors which can be used include, but are not limited to the following vectors or their derivatives: human or animal viruses such as vaccinia virus or adenovirus; insect viruses such as baculovirus; yeast vectors; bacteriophage vectors (e.g. , lambda), and plasmid and cosmid DNA vectors, to name but a few.

Examples of unicellular hosts contemplated by the present invention include, but are not limited to £. coli Pseudonomas, Bacillus, Streptomyces, yeast, CHO, Rl. l, B-W, L-M, COSl , COS7, BSCl, BSC40, BMT10 and Sf9 cells. In addition, a host cell strain may be chosen which modulates the expression of a variant allele comprising a human mu opioid receptor gene, or an isolated nucleic acid hybridizable thereto under standard hybridization conditions, such that the gene product is modified and processed in the specific fashion desired. Different host cells have characteristic and specific mechanisms for the translational and post-translational processing and modification (e.g. , glycosylation, cleavage [e.g. , of signal sequence]) of proteins. Appropriate cell lines or host systems can be chosen to ensure the desired modification and processing of the foreign protein expressed. For example, expression in a bacterial system can be used to produce an nonglycosylated core protein product However, a translocation signal sequence of an isolated variant allele of a human mu opioid receptor gene of the present invention, or an isolated nucleic acid hybridizable thereto under standard hybridization conditions, expressed in bacteria may not be properly spliced Expression in yeast can produce a glycosylated product Expression in eukaryotic cells can increase the likelihood of "native" glycosylation and folding Moreover, expression m mammalian cells can provide a tool for reconstituting, or constituting activity of the variant human mu opioid receptor gene Furthermore, different vector/host expression systems may affect processing reactions, such as proteolytic cleavages, to a different extent

Vectors are introduced into the desired unicellular hosts by methods known in the art, e g , transfection, electroporation, microinjection, transduction, cell fusion, DEAE dextran, calcium phosphate precipitation, hpofection (lysosome fusion), use of a gene gun, or a DNA vector transporter (see, e g , Wu et al , 1992, J Biol Chem 267 963-967, Wu and Wu, 1988, J Biol Chem 263 14621-14624, Hartmut et al , Canadian Patent Application No 2,012,311 , filed Marcn 15, 1990)

An isolated vaπant human mu opioid receptor of the present invention produced as an integral membrane protein can be isolated and purified by standard methods Generally, the variant human mu opioid receptor can be obtained by lysmg the membrane with detergents, such as but not limited to, sodium dodecyl sulfate (SDS), Triton X-100, nonidet P-40 (NP-40), digoxin, sodium deoxycholate, and the like, including mixtures thereof Solubihzation can be enhanced by somcation of the suspension Soluble forms of an isolated variant of a human mu opioid receptor can be obtained by collecting culture fluid, or solubilizing inclusion bodies, e g , by treatment with detergent, and if desired somcation or other mechanical processes, as described above The solubihzed or soluble protein can be isolated using various techniques, such as polyacrylamide gel electrophoresis (PAGE), lsoelectπc focusing, 2-dιmensιonal gel electrophoresis, chromatography (e g , ion exchange, affinity, immunoaffinity, and sizing column chromatography), centπfugation, differential solubility, immunoprecipitation, or by any other standard technique for the purification of proteins

Due to the degeneracy of nucleotide coding sequences, other DNA sequences which encode the variant human mu opioid receptors of the present invention may be used m the practice of the present invention These include but are not limited to allelic genes, homologous genes from other species, and nucleotide sequences comprising all or portions of genes which are altered by the substitution of different codons that encode the same ammo acid residue within the sequence, thus producing a silent change Likewise, the conserved variants of human mu opioid receptors of the present invention include, but are not limited to, those containing, as a primary amino acid sequence, substitutions of amino acids in a variant human mu opioid receptor as set forth above, which are functionally equivalent to ammo acids of the variations set forth above, resulting in a conservative ammo acid substitution For example, one or more ammo acid residues within the sequence can be substituted by another amino acid of a similar polarity, which acts as a functional equivalent, resulting in a silent alteration Substitutes for an amino acid within the sequence may be selected from other members of the class to which the amino acid belongs For example, the nonpolar (hydrophobic) amino acids include alanine, leucine, lsoleuc e, vahne, proline, phenylalanme, tryptophan and methiomne Amino acids containing aromatic ring structures are phenylalanme, tryptophan, and tyrosine The polar neutral amino acids include glycine, seπne, threonine, cysteine, tyrosine, asparagine, and glutamine The positively charged (basic) amino acids include arginine, lysine and histidine The negatively charged (acidic) amino acids include aspartic acid and glutamic acid Such alterations will not be expected to affect apparent molecular weight as determined by polyacrylamide gel electrophoresis, or lsoelectπc point

Particularly preferred substitutions are

- Lys for Arg and vice versa such that a positive charge may be maintained, - Glu for Asp and vice versa such that a negative charge may be maintained,

- Ser for Thr such that a free -OH can be maintained, and

- Gin for Asn such that a free NH₂ can be maintained

Amino acid substitutions may also be introduced to substitute an amino acid with a particularly preferable property For example, a Cys may be introduced at a potential site for disulfide bridges with another Cys A His may be introduced as a particularly "catalytic" site (l e , His can act as an acid or base and is the most common ammo acid in biochemical catalysis) Pro may be introduced because of its particularly planar structure, which induces β-turns m the protein's structure

Antibodies to Variant Human mu Opioid Receptors of the Present Invention According to the invention, variant human mu opioid receptors disclosed herein may be used as an immunogen to generate antibodies that recognize the claimed variant mu opioid receptors Such antibodies include but are not limited to polyclonal, monoclonal, chimeric, single chain, Fab fragments, and an Fab expression library Furthermore, antibodies of the invention may be cross reactive, e g , they may recognize human mu opioid receptors comprising an amino acid sequence of SEQ ID NO 1 , as well as mu opioid receptors from different species Polyclonal antibodies have gi eater likelihood of cross reactivity

Alternatively, an antibody of the invention may be specific for a specific variant allele of a mu opioid receptor

Various procedures known in the art may be used for the production of polyclonal antibod- les to variant opioid receptors disclosed herein For the production of an antibody, various host animals can be immunized by injection with a vaπant human mu opioid receptor of the invention, including but not limited to rabbits, mice, rats, sheep, goats, etc In one embodiment, the variant human mu opioid receptor can be conjugated to an immunogenic carrier, e g , bovine serum albumin (BSA) or keyhole limpet hemocyanin (KLH) Various adjuvants may be used to increase the immunological response, depending on the host species, including but not limited to Freund s (complete and incomplete), mineral gels such as aluminum hydroxide surface active substances such as lysolecithin, pluronic polyols, polyanions, peptides. oil emulsions, keyhole limpet hemocyamns, dimtrophenol, and potentially useful human adjuvants such as BCG (bacille Calmette-Guerm) and Corvnebactenum parvum

For preparation of monoclonal antibodies directed toward a particular human mu opioid receptor of the present invention, any technique that provides for the production of antibody molecules by continuous cell lines in culture may be used These include but are not limited to the hybridoma technique originally developed by Kohler and Milstein [Nature 256 495-497 (1975)], as well as the tπoma technique, the human B-cell hybridoma technique [Kozbor et al , Immunology Today 4 72 1983), Cote et al , Proc Natl Acad Sci U S A 80 2026-2030 (1983)], and the EBV-hybπdoma technique to produce human monoclonal antibodies [Cole et al , in Monoclonal Antibodies and Cancer Therapy, Alan R Liss, Inc , pp 77-96 (1985)] In an additional embodiment of the invention, monoclonal antibodies can be produced in germ-free animals utilizing recent technology [PCT/US90/02545] In fact, according to the invention, techniques developed for the production of "chimeric antibodies" [Morrison et al , J Bacteriol 159 870 (1984),

Neuberger et al , Nature 312 604-608 (1984), Takeda et al , Nature 314 452-454 (1985)] by splicing the genes from a mouse antibody molecule specific for a variant human mu opioid receptor of the present invention together with genes from a human antibody molecule of appropriate biological activity can be used, such antibodies are within the scope of this invention Such human or humanized chimeric antibodies are preferred for use in determining the presence of a particular human mu opioid receptor in a sample taken from a subject

According to the invention, techniques described for the production of single chain antibodies [U S Patent Nos 5,476,786 and 5, 132,405 to Huston, U S Patent 4,946.778] can be adapted to produce particular variant mu opioid receptor-specific single chain antibodies An additional embodiment of the invention utilizes the techniques described for the construction of Fab expression libraries [Huse et al , Science 246 1275-1281 (1989)] to allow rapid and easy identification of monoclonal Fab fragments with the desired specificity for a variant mu opioid receptor of the present invention

Antibody fragments which contain the ldiotype of the antibody molecule can be generated by known techniques For example, such fragments include but are not limited to the F(ab')₂ fragment which can be produced by pepsin digestion of the antibody molecule, the Fab' fragments which can be generated by reducing the disulfide bridges of the F(ab')ι fragment, and the Fab fragments which can be generated by treating the antibody molecule with papain and a reducing agent

In the production of antibodies, screening for the desired antibody can be accomplished by techniques known in the art, e g , radioimmunoassay, ELISA (enzyme-linked immunosorbant assay), 'sandwich" immunoassays, immunoradiometric assays, gel diffusion precipitm reactions, immunodiffusion assays, in situ immunoassays (using colloidal gold, enzyme or radioisotope labels, for example), western blots, precipitation reactions, agglutination assays (e g , gel agglutination assays, hemagglutination assays), complement fixation assays, lmmunofluorescence assays, protein A assays, and lmmunoelectrophoresis assays, etc In one embodiment, antibody binding is detected by detecting a label on the primary antibody In another embodiment, the primary antibody is detected by detecting binding of a secondary antibody or reagent to the primary antibody In a further embodiment, the secondary antibody is labeled Many means are known in the art for detecting binding m an immunoassay and are withm the scope of the present invention For example, to select antibodies which recognize a specific epitope of a variant human mu opioid receptor of the present invention, one may assay generated hybπdomas for a product which binds to a fragment of the variant human mu opioid receptor containing such epitope

The foregoing antibodies can be used in methods known in the art relating to the localization and activity of a variant human mu opioid receptor, e g , for Western blotting, imaging a variant human mu opioid receptor in situ, measuring levels thereof in appropriate physiological samples etc using any of the detection techniques mentioned above or known

Yet another embodiment is based on Applicants remarkable discovery that suφπsmgly, certain variant human mu opioid receptors have greater affinity for particular opioids than human mu opioid receptors comprising an amino acid sequence of SEQ ID NO 2 More specifically, Applicants have discovered that suφπsingly, a variant human mu opioid receptor produced from expression of a vaπant allele of a human mu opioid receptor comprising a variation in SEQ ID NO 1 , wherein the variation comprises A118G. binds three times more tightly to β-endoφhm, an endogenous opioid comprising 31 ammo acid residues, than do human mu opioid receptors produced from the expression of the predominant or "most common" allele comprising a DNA sequence of SEQ ID NO 1 Since β-endoφhin is believed to play an important role in numerous physiological functions, the presence of a variant comprising A118G, in either or both alleles present m a subject has an impact on such physiological functions Furthermore, β-endoφhin induced activity of a receptor produced from the expression of a variant allele of a human mu opioid receptor gene comprising the A118G polymoφhism effected the receptor's activation of GIRK channels via a G protein-mediated mechanism relative to the activity of a receptor produced from the expression of the predominant or most common" allele Consequently, a subject having an Al 18G variation, in either or both alleles of a human mu opioid receptor gene is expected to have lower susceptibility and greater tolerance to pam relative to a person comprising two copies of the predominant or "most common" allele

One such function involves a susceptibility to at least one addictive disease, such as opioid addiction, cocaine addiction or addiction to other psychostimulants, nicotine addiction, barbiturate or sedative hypnotic addiction, anxiolytic addiction, or alcohol addition In particular, Applicants have discovered a variant allele of a human mu opioid receptor gene comprising a DNA sequence having at variation in SEQ ID NO 1 , wherein the variation comprises A118G, is present in an Hispanic study population at a statistically significant greater frequency m the genomes of persons not suffering from at least one addictive disease, relative to its presence in the genomes of persons suffering from an addictive disease, such as opioid addiction

Moreover, the inventors herein have further discovered that another variant allele of a human mu opioid receptor gene comprising a DNA sequence having a variation m SEQ ID NO 1, wherein the variation comprises C17T, is present at a statistically significant greater frequency in the genomes of persons suffering from at least one addictive disease, relative to its presence in the genome of persons not suffering from at least one addictive disease Furthermore, and as shown in the Examples below, it has been found that the C17T variant mu opioid receptor has a β-endoφhm binding affinity approximately 0 72 times that of the human mu opioid receptor produced from expression of the predominant or "most common allele of the human mu opioid receptor gene The decreased binding affinity of this variant is in contrast to the increased affinity of the A 118G variant mentioned above In addition, one of the important indices of cellular functioning of the mu opioid receptor is the inhibition of adenylyl cyclase activity following agonist binding to the receptor The C17T variant mu opioid receptor has been found to be less sensitive to two endogenous opioids, β-endoφhm and leu-enkephahn, than the receptor produced by the "most common" allele the EC50 values differed by a factor of approximately 2 7 and 2 8, respec- lively

Hence, a variant allele of a human mu opioid receptor gene comprising a DNA sequence having an A118G variation, in SEQ ID NO 1 , has increased affinity for β-endoφhm and capability of effecting activation of GIRK channels via a G protein-mediated mechanism provides resistance against susceptibility to addictive diseases, while a variant allele comprising a human mu opioid receptor having a C17T variation in SEQ ID NO 1, has a decreased affinity for β-endoφhm and a decreased sensitivity to adenylyl cyclase inhibition by the endogenous ligands β-endoφhm and leu-enkephahn, and is indicative of increased susceptibility to at least one addictive disease These differences in variant mu opioid receptor function at the biochemical and cellular level and their correlations with physiological manifestations m susceptibility to addictive disease provides a basis for the value of the identity of alleles in identifying individual susceptibility to addictive disease, pain, reaction to therapeutic agents, etc

Consequently, the present invention extends to a method for determining a susceptibility of a subject to one addictive disease comprising removing a bodily sample comprising a first and second allele of a human mu opioid receptor gene from the subject, and determining whether either the first or second alleles, or both alleles comprise a DNA sequence having at least one variation in SEQ ID NO 1 , wherein the variation comprises

A118G or

C17T

The presence of the variation of C17T in either or both alleles of a human mu opioid receptor gene of a sample from the subject indicates the subject has an increased susceptibility to at least one addictive disease relative to a standard having alleles of the human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO 1

Furthermore, the presence of the variation of comprising Al 18G, in either or both alleles of a mu opioid receptor gene in a sample from the subject is expected to indicate the subject as a decreased susceptibility to addictive diseases relative to a standard comprising alleles of a human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO 1

In this embodiment, the biological sample can be a biological fluid, such as bui not limited to, blood, serum, plasma, interstitial fluid, plural effusions, urine, cerebrospmal fluid, and the like Preferably, variant alleles of a human mu opioid receptor gene, as described above, are detected in serum or urine, which are both readily obtained Alternatively, variant alleles of a human mu opioid receptor gene indicating increased or decrease susceptibility to addictive diseases in the subject as described above, can be detected from cellular sources, such as, but not limited to, brain tissue biopsies, adipocytes, testes, heart, and the like For example, cells can be obtained from an individual by biopsy and lysed, e g , by freeze-thaw cycling, or treatment with a mild cy to lytic detergent such as, but not limited to, TRITON X-100^®, digitonin, NONIDET P (NP)-40^®, saponin, and the like, or combinations thereof (see, e g , International Patent Publication WO 92/08981, published May 29, 1992) In yet another embodiment, samples containing both cells and body fluids can be used (see ibid )

Other methods presently understood by a skilled artisan, and encompassed by the present invention, can also be used to detect the presence of either variation in either or both alleles of a human mu opioid receptor gene m a sample, and hence increased or decreased susceptibility to at least one addictive disease of the subject relative to the susceptibility of at least one addictive disease in a standard comprising alleles of the human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO 1

1 For example, an optionally detectably labeled isolated nucleic acid molecule hybridizable under standard hybridization conditions to an isolated variant allele of a human mu opioid receptor gene comprising a DNA sequence having a variation in

SEQ ID NO 1 , wherein the variation comprises C17T, can be used in standard Northern hybridization analysis to detect the presence, and in some instances quantitate the level of transcription of such a variant allele of the present invention The presence of this variant allele in a bodily sample from a subject is expected to be indicative of increased susceptibility to at least one addictive disease in the subject Likewise, an optionally detectably labeled isolated nucleic acid molecule hybridizable under standard hybridization conditions to an allele of a human mu opioid receptor gene comprising a DNA sequence having a variation in SEQ ID NO 1, wherein the variation comprises A118G can be used in a standard Northern hybridization analysis to detect the presence of a variant allele in the sample comprising a variation in SEQ ID NO 1, wherein the variation comprises A118G, which is expected to be indicative of a decreased susceptibility to at least one addictive disease relative to the susceptibility of a standard comprising two alleles of a human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO: l.

Alternatively, oligonucleotides of the invention can be used as PCR primers to amplify an allele of a human mu opioid receptor gene of the biological sample e.g. , by reverse transcriptase-PCR, or amplification of the allele itself. The amplified mRNA or DNA can then be quantified or sequenced in order to determine the presence of a variant allele, and the susceptibility of the subject to addictive diseases. Furthermore, variations in SEQ ID NO: l, as described above, can be found by creation or deletion of restriction fragment length polymoφhisms (RFLPs) not found in the predominant or "most common" allele, hybridization with a specific probe engineered to hybridize to variation described above under standard hybridization conditions, (or lack of hybridization with a probe specific for the predominant or "most common" allele), as well as by other techniques.

Furthermore, biochemical or immunochemical/biochemical (e.g. , immunoprecipitation) techniques can be used to detect the presence and or level of expression of a variant allele of a human mu opioid receptor gene comprising a DNA sequence having a variation in SEQ ID NO: l , wherein the variation comprises:

A118G; or

C17T.

The presence of the Al 18G variation in either or both alleles of a human mu opioid receptor gene in a biological sample from the subject indicates a decreased susceptibility to addictive diseases in the subject, and the presence of the C17T variation in either or both alleles of a human mu opioid receptor gene in a biological sample from the subject indicates increased susceptibility to addictive diseases in the subject. For example, methods such as radioimmunoassay, ELISA (enzyme-linked immunosorbant assay), "sandwich" immunoassays, immunoradiometric assays, gel diffusion precipitin reactions, immunodiffusion assays, in situ immunoassays (using colloidal gold, enzyme or radioiso- tope labels, for example), western blots, precipitation reactions, agglutination assays (e.g. , gel agglutination assays, hemagglutination assays), complement fixation assays, immunofluorescence assays, protein A assays, and immunoelectrophoresis assays, etc using antibodies of the present invention, can be used to determine the presence of a variant an allele of a human mu opioid receptor gene m a sample taken from the subject, and hence, the subject's susceptibility to addictive diseases relative to the susceptibility of a standard In one embodiment, antibody binding is detected by detecting a label on the primary antibody In another embodiment, the primary antibody is detected by detecting binding of a secondary antibody or reagent to the primary antibody In a further embodiment, the secondary antibody is labeled Many means are known in the art for detecting binding in an immunoassay and are within the scope of the present invention

Determining susceptibility to pain in a Subiect

In yet another embodiment, the present invention extends to a method for determining a susceptibility to pam in a subject As explained above, Applicants have discovered that endogenous opioid, such as β-endoφhin, bind about three times as tightly to a variant human mu opioid receptor comprising an amino acid sequence having a in SEQ ID NO 2 wherein the variation comprises Asn40Asp, relative to the binding of β-endorphin to a human mu opioid receptor comprising an amino acid sequence of SEQ ID NO 2, encoded by the predominant or most common" allele of a human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO 1 Also, β-endoφhin induced activity of a receptor produced from the expression of a variant allele of a human mu opioid receptor gene or an isolated nucleic acid molecule hybridizable thereto under standard hybridization conditions comprising the Al 18G polymoφhism effected the receptor's activation of GIRK channels via a G protein-mediated mechanism relative to the activity of a receptor produced from the expression of the predominant or ' most common allele Consequently, a subject having an Al 18G variation, in either or both alleles of a human mu opioid receptor gene is expected to have lower susceptibility and greater tolerance to pam relative to a person comprising two copies of the predominant or "most common" allele

Applicants have further discovered a variant allele of a human mu opioid receptor gene comprising a DNA sequence having a variation m SEQ ID NO 1 , wherein the variation comprises C17T, is present at a statistically significantly greater frequency in the genomes of opioid addicts relative to its presence in the genomes of persons not addicted to opioids Hence, the presence of a variant allele of a human mu opioid receptor comprising a DNA sequence having a variation m SEQ ID NO 1, wherein the variation comprises C17T, in a biological sample taken from a subject, indicates the subject is predicted to have increased susceptibility and decreased tolerance to pam

Hence, disclosed herein is a method of determining susceptibility of pain in a subject, comprising the steps of removing a bodily sample comprising a first and second allele of a human mu opioid receptor gene from the subject, and determining whether either the first or second alleles, or both alleles, comprise a DNA sequence having at least one variation in SEQ ID NO 1 , wherein the variation comprises

A118G, or

C17T

The presence of at least one variation in either or both alleles of the human mu opioid receptor gene is expected to be indicative of the subject's increased or decreased susceptibility to pain relative to a person homozygous with respect to the predominant or "most common" allele comprising a human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO 1

Numerous methods presently available, and understood by the skilled artisan, can be used to ' genotype" a subject in regards to the presence of a variant allele of a human mu opioid receptor gene in the genome of the subject In particular, methods described above to ascertain increased or decreased susceptibility to addictive diseases have relevance in this embodiment of the present invention, and can readily be used herein For example, Northern blot hybridization an isolated nucleic acid of the present invention hybridizable under standard hybridization conditions to an isolated variant allele of a human mu opioid receptor gene comprising a DNA sequence having a variation of SEQ ID NO 1 , wherein the variation comprises

A118G, or

C17T, as a probe, along with RT-PCR, PCR, and numerous immunoassays described above, have applications herein

Moreover, once susceptibility to pam in a subject has been determined, it is possible for attending medical professionals treating the subject for pam to administer an appropriate amount of pam reliever to the subject in order to induce analgesia More specifically, an inappropriate amount of pam reliever is administered to a subject when either the subject is not relieved of pam, or the subject is exposed to potential deleterious side effects of the pain reliever, such as induction of addiction to the pain reliever, brain damage, or death

However, since the amount of pain reliever administered to a subject is presently based principally on weight, information regarding the genotype of the subject with respect to the human mu opioid receptor gene can help increase accuracy in determining a therapeutically effective amount of pain reliever to administer in order to induce analgesia, making the use of pain relievers much safer for the subject

Similarly, once ascertained, a susceptibility to addiction and response to human mu opioid receptor directed therapeutic agents, appropriate medications and dosages thereof can be determined for treatment of addictive diseases

Diagnosing and treating a disease or disorder related to a physiological function regulated by the HPA or HPG axes In yet another embodiment, the present invention extends to a method for diagnosing a disease or disorder related to a physiological function regulated by the HPA or HPG axes Examples of such physiological functions include sexual or reproductive functions, gastrointestinal motihty, immune response or ability to withstand stress Moreover, examples of diseases or disorders which can be diagnosed with the present invention include infertility, constipation diarrhea, and decreased immune response to name only a few

As explained above, Applicants have discovered that endogenous opioid, such as β- endoφhin, bind about three times as tightly to a variant human mu opioid receptor comprising an amino acid sequence having a m SEQ ID NO 2 wherein the variation comprises Asn40Asp, relative to the binding of β-endoφhin to a human mu opioid receptor comprising an ammo acid sequence of SEQ ID NO 2, encoded by the predominant or "most common" allele of a human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO 1 Also, β-endoφhm induced activity of a receptor produced from the expression of a variant allele of a human mu opioid receptor gene or an isolated nucleic acid molecule hybridizable thereto under standard hybridization conditions comprising the A118G polymoφhism effected the receptor's activation of GIRK channels via a G protein-mediated mechanism relative to the activity of a receptor produced from the expression of the predominant or "most common" allele Consequently, a subject having an A118G variation, in either or both alleles of a human mu opioid receptor gene is expected to have has increased activity of the receptor relative to the activity of a receptor produced from expression of the predominant or "most common" allele comprising a DNA sequence of SEQ ID NO 1 This increased activity is expected to result in lower activity of the HPA and HPG axes As a result sexual and reproductive functions, gastrointestinal motihty, immune response and/or ability to withstand stress are expected to be increased m the subject relative to the levels of such functions in a standard comprising two alleles of the mu opioid receptor gene comprising a DNA sequence of SEQ ID NO 1

In contrast, Applicants have discovered a human mu opioid receptor produced from expression of the C17T vaπant allele of the human mu opioid receptor gene is expected to have decreased binding affinity for β-endoφhin relative to the binding affinity of a human mu opioid receptor protein produced from the expression of the predominant or 'most common" allele of the human mu opioid receptor gene (SEQ ID NO 1) comprising a DNA sequence of SEQ ID NO 1 Consequently, a variant receptor encoded by a C17T variant allele exhibits decreased activity relative to the predominant or 'most common" allele This decreased activity is expected to result in increased activity of HPA and HPG axes Hence, sexual and reproductive functions, gastrointestinal motihty, immune response and/or ability to withstand stress are expected to be decreased in the subject relative to the levels of such physiological functions in a standard comprising two alleles of the mu opioid receptor gene comprising a DNA sequence of SEQ ID NO 1

Hence, disclosed herein is a method of diagnosing a disease or disorder related to a physiological function regulated by the HPA or HPG axes m a subject, comprising the steps of removing a bodily sample comprising a first and second allele of a human mu opioid receptor gene from the subject, and determining whether either the first or second alleles or both alleles, comprise a DNA sequence having at least one variation in SEQ ID NO 1 , wherein the variation comprises

A118G, or C17T

The presence of at least one variation in either or both alleles of the human mu opioid receptor gene is expected to be indicative of a disease or disorder related to a physiological function regulated by the HPA or HPG axes relative to such functions in a person homozygous with respect to the predominant or "most common ' allele comprising a human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO 1 Examples of such physiological functions include sexual or reproductive functions, gastrointestinal moti ty, immune response, or ability to withstand stress Moreover, examples of diseases or disorders which can be diagnosed with the present invention include infertility, constipation, diarrhea, and decreased immune response to name only a few relative to a person homozygous with respect to the predominant or "most common allele comprising a human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO 1

Numerous methods presently available, and understood by the skilled artisan, can be used to "genotype" a subject in regards to the presence of a vaπant allele of a human mu opioid receptor gene in the genome of the subject In particular, methods described above to ascertain increased or decreased susceptibility to addictive diseases have relevance in this embodiment of the present invention, and can readily be used herein For example,

Northern blot hybridization an isolated nucleic acid of the present invention hybridizable under standard hybridization conditions to an isolated variant allele of a human mu opioid receptor gene comprising a DNA sequence having a variation of SEQ ID NO 1, wherein the variation comprises

A118G, or C17T, as a probe, along with RT-PCR, PCR, and numerous immunoassays described above, have applications herein

In an alternative, such a method comprises removing a bodily sample from the subject comprising a mu opioid receptor, and determining whether the receptor comprises an ammo acid sequence having a variation in SEQ ID NO 1 , wherein the variation comprises Asn40Asp or conserved variants thereof, or AlaόVal or conserved variants thereof, such that the presence of at least one variation is expected to be indicative of a disease or disorder related to a physiological function regulated by the HPA or HPG axes, such as sexual function or development, gastric motihty, immune response, or the ability of the subject to withstand stress, relative to regulation of such activities in a standard comprises a human mu opioid receptor having an ammo acid sequence of SEQ ID NO 2

In particular, the presence of a variant human mu opioid receptor comprising an amino acid sequence having at least one variation in SEQ ID NO 2 wherein the variation comprises Asn40Asp or conserved variants thereof, is expected to be indicative of increased sexual or reproductive functions increased gastrointestinal motihty, increased immune response, or increased ability to withstand stress relative to the levels of such function observed in a standaid having a mu opioid receptor comprising an ammo acid sequence of SEQ ID NO 2

Furthermore, the presence of a variant human mu opioid receptor comprising an ammo acid sequence having a variation in SEQ ID NO 2, wherein the variation comprises AlaόVal or conserved variants thereof, in a bodily sample taken from a subject is expected to be indicative of decreased sexual or reproductive functions, decreased gastrointestinal motihty, decreased immune response, or decreased ability to withstand stress relative to the levels of such function observed in a standard having a mu opioid receptor comprising an amino acid sequence of SEQ ID NO 2 Examples of specific diseases or disorders related to regulation of physiological functions regulated by the HPA or HPG axes include infertility, constipation, diarrhea, decreased immune response to antigens or a lack of ability to withstand stress

Numerous methods of detecting a variant mu opioid receptor as described above are presently available to the skilled artisan For example a receptor in the bodily sample can be digested into fragments with proteases or CNBr These fragments can then be collected and sequenced using presently known methods Once the sequence of the receptor has been determined, it is a simple matter of comparing it to the amino acid sequence of the predominant or "most common" receptor having an amino acid sequence of SEQ ID NO.2, to determine whether a variation m the amino acid sequence exists Other methods involve immune assays described herein using antibodies of the present invention, or a binding assay to determine the binding affinity of the receptor to β-endoφhm If its binding to β- endoφhin is approximately 3 times greater than the known binding affinity of the predominant or "most common" receptor for β-endoφhin, then the receptor is expected to have an ammo acid sequence having a variation in SEQ ID NO 2, wherein the variation comprises Asn40Asp or conserved variants thereof, and is expected to be indicative of a disease or disorder related to increased sexual or reproductive functions, increased gastrointestinal motihty, increased immune response, or increased ability to withstand stress

Moreover, once a disease or disorder related to a physiological condition regulated by the HPA or HPG axes has been diagnosed, it is possible for attending medical professionals treating the suspect to select an appropriate therapeutic agent for treating such a disease and disorder, and a therapeutically effective amount of such pain reliever to administer to the subject Hence naturally, the present invention extends to a method for selecting an appropriate therapeutic agent for treating a disease or disorder related to a physiological function regulated by the HPA and HPG axes, wherein such physiological functions include sexual and reproductive functions, gastrointestinal motihty, immune response, and ability to withstand stress Furthermore, diseases or disorders related to such functions which can be diagnosed with the present invention include, but are not limited to, infertility, constipation, diarrhea, and decreased immune response, to name only a few

Commercial Kits Furthermore, as explained above, the present invention extends to commercial kits having applications in screening a bodily sample taken from a subject tor the presence of a variant allele comprising a human mu opioid receptor comprising a DNA sequence having a variation in SEQ ID NO 1 , wherein the variation comprises A118G, C17T

With information obtained from the use of a test kit of the present invention, an attending health profession can determine whether the subject has an susceptibility to pam relative to a standard, an increased susceptibility to at least one addictive disease relative to the susceptibility of a standard, a therapeutically effective amount of pain reliever to administer to the subject suffering from pam m order to induce analgesia in the subject relative to the therapeutically effective amount of pam reliever to administer to a standard m order to induce analgesia in the standard, or a therapeutically effective amount therapeutic agent to administer to a subject suffering from at least one addictive disease, relative to the therapeutically effective amount of therapeutic agent to administer to standard suffering from at least one addictive disease Furthermore, such information can also be used to diagnose a disease or disorder related to a physiological function regulated by the HPA or HPG axes, such as sexual or reproductive functions, gastrointestinal motihty, immune response, or ability to withstand stress, or selecting an appropriate therapeutic agent and a therapeutically effective amount of such an agent to administer to a subject suffering from a disease or disorder related to a physiological function regulated by the HPA or HPG axes In each use described above, the standard comprises a first and or second allele ot a human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO 1

Accordingly, a test kit of the present invention for determining whether a subject comprises a variant allele of a human mu opioid receptor gene comprising a DNA sequence having a variation m SEQ ID NO 1 , comprises means for detecting the presence of a variation m a first and or second allele comprising a human mu opioid receptor in a biological sample from a subject, and optimally packaged with directions for use of the kit In one particular aspect, the means for detecting the presence of a variant allele of a human mu opioid receptor gene comprising a DNA sequence having a variation in SEQ ID NO 1 , comprises a specific binding partner of a human mu opioid receptor, such as an antibody, and means for detecting the level of binding of the specific binding partner of the antibody to the particular human mu opioid receptor In another embodiment, a test kit comprises an oligonucleotide probe for binding to a variant allele of a human mu opioid receptor gene comprising a DNA sequence having a variation in SEQ ID NO 1 , and means for detecting the level of binding of the probe to the variant allele, wherein detection binding of the probe to the variant allele indicates the presence of a variant comprising a human mu opioid receptor gene comprising a DNA sequence having a variation in SEQ ID NO 1 , wherein the variation comprises A118G, or

C17T

The sequence of the oligonucleotide probe used m a commercial kit will determine which if any variation is present in an allele comprising a human mu opioid receptor gene Should no binding be detected, it is probable that no such variation exists in either allele of the subject

More specifically, a commercial test kit of the present invention comprises a) PCR oligonucleotide primers suitable for detection of a variant allele of a human mu opioid receptor gene comprising a DNA sequence having a variation in SEQ ID NO 1, as set forth above, b) other reagents, and c) directions for use of the kit

Examples of PCR oligonucleotide primer suitable for detection of an allele comprising a human mu opioid receptor gene comprising a DNA sequence having a variation in SEQ ID NO 1 can be readily produced bv a person of ordinary skill in the art with teaching set forth herein, and variations of SEQ ID NO 1 also set forth herein

The present invention further extends to commercial test kits capable of detecting a variant human mu opioid receptor m a bodily sample taken from a subject Examples of variant human mu opioid receptors that can be detected with a kit of the present invention com- prise a variant human mu opioid receptor comprising an amino acid sequence having a variation in SEQ ID NO 2, wherein the variation comprises the variation comprises Arg260Hιs or conserved variants thereof, or a variant human mu opioid receptor comprising an amino acid sequence having at least two variations in SEQ ID NO 2, wherein the variations comprise

Asn40Asp or conserved variants thereof

AlaόVal or conserved variants thereof, or

Arg260Hιs or conserved variants thereof

Moreover, a commercial test kit of the present invention can be used to determine a susceptibility to pain in a subject relative to a standard, an increased susceptibility to at least one addictive disease in a subject relative to the susceptibility of a standard, a therapeutically effective amount of pam reliever to administer to the subject suffering from pain in order to induce analgesia in the subject relative to the therapeutically effective amount of pain reliever to administer to a standard in order to induce analgesia in the standard, a therapeutically effective amount of a therapeutic agent to administer to a subject suffering from at least one addictive disease, relative to the therapeutically effective amount of therapeutic agent to administer to standard suffering from at least one addictive disease, a diagnosis of a disease or disorder related to a physiological function regulated by the HPA or HPG axes, such as sexual or reproductive functions, gastrointestinal motility, immune response, or ability to withstand stress, or selecting an appropriate therapeutic agent and a therapeutically effective amount of such an agent to administer to a subject suffering from a disease or disorder related to a physiological function regulated by the HPA or HPG axes. In each use described above, the standard comprises a first and or second allele of a human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO: l .

Accordingly, the present invention extends to a commercial test kit having applications set forth above, comprising a predetermined amount of at least one detectably labeled immuno- chemically reactive component having affinity for a variant human mu opioid receptor;

(b) other reagents; and

(c) directions for use of the kit.

Antibodies of the present invention, and set forth above, have readily applications in a commercial test kit of the present invention.

In a further variation, the test kit may be prepared and used for the puφoses stated above, which operates according to a predetermined protocol (e.g. "competitive, " "sandwich, " "double antibody, " etc.), and comprises:

(a) a labeled component which has been obtained by coupling the human mu opioid receptor of a bodily sample to a detectable label;

(b) one or more additional immunochemical reagents of which at least one reagent is a ligand or an immobilized ligand, which ligand is selected from the group consisting of: (i) a ligand capable of binding with the labeled component (a);

(ii) a ligand capable of binding with a binding partner of the labeled component

(a);

(iii) a ligand capable of binding with at least one of the component(s) to be determined, and

(IV) a ligand capable of binding with at least one of the binding partners of at least one of the component(s) to be determined, and

(c) directions for the performance of a protocol for the detection and/or determination of one or more components of an immunochemical reaction between the human mu opioid receptor gene of the present invention and a specific binding partner thereto

The present invention may be better understood by reference to the following non-limiting Example, which is provided as exemplary of the invention The following Example is presented in order to more fully illustrate the preferred embodiments of the invention It should in no way be construed, however, as limiting the broad scope of the invention

EXAMPLE The mu opioid receptor is the major target for clinically important opioid alkaloids including moφhine, methadone, fentanyl, and other opioid drugs (1,3), as well as for endogenous opioid peptides such β-endorphin, Met-enkephahn-Arg-Phe, and the recently identified endomoφhins (5) Furthermore it is the major molecular site of action for heroin (2,6) Rapid activation of the mu opioid receptor, such as occurs in the setting of drug abuse, results in a euphoric effect, thus conferring the reinforcing or rewarding effects of the drug, contributing to the development of addiction Clinical observations have suggested that individuals have varied sensitivity to opioids, suggesting potential variability in the receptor protein and gene

Molecular cloning of the mu opioid receptor (7-9) has made it possible to determine potential sequence polymoφhism, as shown by a recent study (10) To further identify SNPs of the mu opioid receptor, a PCR-based strategy was used to amplify the coding regions of the mu opioid receptor gene, and to determine the DNA sequence of the amplified exons Using this method DNA samples were sequenced from 152 subjects including both former heroin addicts in methadone maintenance treatment and individuals with no history of opiate or non-opiate drug dependence

RESULTS AND DISCUSSION Recent studies have shown that up to 90% of persons entering treatment for herom addiction also abuse cocaine, alcohol or other drugs However, following stabilization on methadone maintenance pharmacotherapy (treatment for one year or more), the percentage of patients who continue to abuse cocaine drops to approximately 30% and alcohol to 25 to 30% (11-13) Rigorous characterization of substance abuse profiles was therefore obtained for all study subjects Self reported drug abuse history was confirmed for addictive disease patients by routine urine toxicology Also, since 20% to 50 % of persons with chemical dependency may have a definable mental disorder which can be characterized by standard diagnostic criteria and also since a similarly high percentage of persons with a diagnosed mental illness have chemical dependency, extensive psychological and psychiatric evaluations of study subjects were performed (14, 15)

Inclusion criteria were met by 152 individuals (refer to Methods for details of inclusion/exclusion criteria) One hundred thirteen of the study subjects (74 3 %) were opiate dependent with or without previous or current co-dependency for other substances, 39 study subjects (25 7%) had no history of drug dependence Study subjects were well balanced between females and males 69 females (45 4%) and 83 males (56 4%) were included in the study subject pool The ethnic breakdown of the study subject populations was as follows African- American 31 , (20 3 %), Caucasian, 52 (34 2%), Hispanic, 67 (44 1 %), Native North- American, 1 , (0 7%) and Other, 1 (0 7%) Although several individuals could be classified into two separate groups if one parent came from one ethnic group and the other parent from another group, including four individuals (2 6%) who reported one parent African- American and one Caucasian, and five individuals (3 3 %) who reported one parent Caucasian and one Hispanic, for the genotype calculations the former were classified as African-American and the latter as Hispanic Within the group of former herom addicts in methadone maintenance treatment, the mean years in treatment was 6 7 with a range from two months to 30 years (N= 112, one patient's history could not be verified) Prior to treatment, the mean years of herom addiction was 10 1 years, with a range from one to 30 years (N = 109, four patients' histories could not be verified) The mean daily methadone dose of opiate dependent patients in stable treatment was 84 mg/day, with a range from 30 to 120 mg/day (N = 106) Only patients with established stable doses were included in this calculation, I e , not on induction, increasing, tapering, or elimination schedules By sequencing PCR-amplified DNA from the study subjects, it was determined that the previously reported sequence for the human mu opioid receptor (8,9) was the most common allele found in the study population Five different SNPs were also identified For the puφose of this study, the term "most common" was used to denote the predominant mu opioid receptor allele and the corresponding receptor that was originally reported by cDNA cloning (8,9), and the term "variant" to denote the allelic genes/receptors containing polymoφhic variations Table 1 shows these SNPs with information on the position of ammo acid substitutions and overall frequency of the variant alleles in the study population. Genotype and allele frequencies for the two most common allelic variants, the A118G and C17T polymoφhisms, are shown in Table 2 The associations of each frequency are broken down by ethnicity, gender, and opioid dependence Since the number of individuals homozygous for the less common alleles was small, allele frequencies rather than genotype frequencies were used to test for significant differences Differences of allele frequencies were tested among the three most common ethnic groups, African- American, Caucasian, and Hispanic, irrespective of opioid dependency status There was significant difference of allele frequencies among ethnic groups for both the A118G [χ² ₍₂₎ = 7 15 (p = 0 028)] and the C17T [χ² ₍₂₎ = 26 0 (p = 0 000002)] If the individuals who reported one parent from one ethnic group and one from another ethnic group were excluded from this analysis, similar significance levels were obtained for differences of both SNPs among ethnic groups This result is not suφπsing since allele frequencies are known to vary among ethnic groups It is important to consider these differences which can confound association analyses No significant association of gender with either polymoφhism was observed For the A118G polymoφhism, there was no significant difference m allele frequencies between opioid dependent and non-dependent study subjects However, the variant T allele at the 17 position was present in a higher proportion of opiate dependent persons in the sample at a marginal significance level [Yates corrected chi-square

054) This result is similar to that obtained in a previous study which identified this one SNP, and examined its frequency m association with drug dependence (10) Table 3 shows the data stratified by ethnic group and opiate dependency status for each of the Al l 8G and C17T polymoφhisms The pooled Relative Risk (RR) and the Mantel-Haenszel chi-square (16) were calculated For the Al 18G polymoφhism there was no significant difference in allele frequencies between opioid dependent persons and those with no history of drug abuse or dependence [RR = 0 48 χ² ₍₁₎= 2 76 (p=0 096)] Although not significant there was evidence of heterogeneity between ethnic groups [RR = 0.48 χ² ₍₂₎ = 5.16 (p =0.076)]. It should be noted that the direction of the Relative Risk less than one denotes here that the Al 18G polymorphism was more frequent in normal healthy volunteers with no history of drug dependence (controls) than opioid dependent subjects (cases), and if present, the Al 18G polymorphism might confer some level of protection against opioid dependence, which is of particular interest given the functional differences (see below). There was a marginally significant difference in the allele frequencies for the C17T polymoφhism between cases and controls [RR = 7.83 χ² ₍₁₎ = 3.73 (p = 0.05)]. The test for heterogeneity among ethnic groups was not significant [χ² ₍₂₎ = 3.95 (p = 0.14)].

Cases and controls were examined for Hardy Weinberg equilibrium (HWE) by each ethnic group individually and for all ethnic groups combined. All groups analyzed were in HWE, except for the C17T polymoφhism for the opioid dependent subjects with all ethnic groups combined which showed significant deviation from HWE (p = 0.008). Although under no obligation to provide a reason for this observation, and not intending to be bound by any postulation to explain this observation, these results may be due to the admixture introduced by combining the different ethnic groups into one sample.

Furthermore, from the first group of individuals from whom the mu opioid receptor has been sequenced (n= 175), the following list of individuals with more than one variant form of the receptor were found: (1) Three individuals were double heterozygous for the A118G and C17T variants. The DNA sequencing methodology used cannot determine whether both SNPs are on a single chromosome or the two SNPs are on different chromosomes. These individuals would therefore be predicted either to express both prototype receptors and receptors that have both amino acid substitutions, or, conversely, two variant receptor types, one with the A6V substitution and the other with the N40D substitution. (2) One individual was a double heterozygote for the A118G SNP and G779A SNP. This individual would therefore be predicted either to express both prototype receptors and receptors that have both amino acid substitutions, or, conversely, two variant receptor types, one with the N40D substitution and the other with the R260H substitution. (3) One individual was homozygous for the C17T SNP and heterozygous for the G924A SNP. This individual is predicted to express variant receptors each of which has the A6V substitution. However the G924A SNP would be useful for ascribing a haplotype in this individual for genetic haplotype analysis.

The most prevalent genetic polymoφhism identified is the A118G SNP with a substitution at the nucleotide position 118 with respect to the first base of the initiator codon for methionine (Fig. 1). This allele was observed in 29 of the 152 subjects, with 26 subjects being heterozygous and 3 being homozygous for the variant allele. This gives an allele frequency of 10.5 % in the subject population that we have examined for this study. Nucleotide no. 118 is the first base in codon no. 40 of the human mu opioid receptor, and the A118G variant predicts an Asn to Asp change in amino acid residue no. 40 of the receptor (N40D). The Asn residue at amino acid position no. 40 in the most common mu receptor is a putative site for N-glycosylation (9); thus, the A118G variant would result in the loss of a putative N-glycosylation site. The position of amino acid 40 is in the N terminal region of the mu opioid receptor (9) . Based on sequence motif similarities with other G protein-coupled receptors (17), the N terminal region of opioid receptors, including that of the mu opioid receptor, is predicted to be in the extracellular space (18). To explore any potential effects of the A118G polymorphism on the mu opioid receptor, position 118 of the most common mu receptor cDNA was mutated by site-directed mutagenesis, and a cDNA clone for the human mu opioid receptor containing the A118G variant was generated. This way, both the most common and the Al 18G variant receptors could be ex- pressed in cells to determine their cellular activity and their binding affinities.

Radioligand binding assays were performed with cell lines stably transfected with either the A118G variant or the most common mu receptor, to determine whether the A118G polymoφhism changes the receptor's ability to bind opioid ligands, especially endogenous opioid peptides, since they are the physiological agonists for the mu opioid receptor. The A118G variant and the most common mu receptors yielded similar binding affinity values for most of the opioid ligands tested, including the small endogenous peptide agonists Met- and Leu-enkephalin, each with five amino acid residues; endomoφhin-1 and -2, each with four residues; the mu-selective synthetic opioid peptide DAMGO, with five amino acid residues; the endogenous ligand for the kappa opioid receptor dynoφhin A (1-17); as well as the mu-preferring opioid alkaloid agonists moφhine, fentanyl, methadone, and the opioid antagonist naloxone (Fig. 2, and data not shown). These results suggest that the A118G polymoφhism does not change the overall binding properties of the mu opioid receptor. This is not unexpected, since the predicted amino acid change as a result of the A118G SNP is a single residue substitution in the N terminal region in the extracellular space, and is unlikely to drastically affect the overall tertiary structure of the receptor.

There was a noticeable change, however, for the A118G vaπant receptor binding of human β-endoφhin, a much larger endogenous opioid peptide, which has 31 amino acid residues and which activates the mu opioid receptor. Whereas the other, smaller, endogenous opioid peptides and alkaloid agonists and antagonist displayed similar binding affinities for both receptors, the A118G variant receptor showed higher binding affinity for β-endoφhin than the most common receptor (Fig. 2), with the ratio of the Ki of the most common to Al 18G variant being 3.46 ± 0.31 (mean ± SEM, n = 3). These results indicate that while the A118G polymoφhism did not alter the overall profile of ligand binding to the receptor, it specifically influenced the β-endoφhin binding and resulted in tighter binding.

An important cellular activity of the mu opioid receptor is inhibition of neuronal excitability by receptor-mediated inhibition of pre-synaptic calcium channels and activation of post- synaptic potassium channels (19, 20). The major effector potassium channels for the mu receptor, as well as for many other G protein-coupled receptors, are the G protein-activated inwardly rectifying K⁺ (GIRK) channels (21,22), and co-expression studies have shown that the mu opioid receptor can readily activate GIRK channels via a G protein-mediated mechanism (9,23,24). To examine the effect of the Al 18G polymorphism, Xenopus oocyte expression was used to compare the A118G variant receptor with the most common mu opioid receptor. Agonist stimulation of the Al 18G variant receptor activated a potassium current similar to that seen with the most common mu opioid receptor (9,23). The EC₅₀ values for endomoφhin-1 are 4.6 nM for the most common receptor and 4.9 nM for the A118G variant receptor (Fig. 3), indicating that endomoφhin-1 activated both receptors with similar potency. The EC₅₀ values for β-endoφhin, however, differed about three fold between the A118G variant and the most common mu opioid receptors (Fig. 3), consistent with the change in the binding affinity (Fig. 2). These data indicate that, as a result of the SNP in the receptor gene, the A118G variant receptor may be functionally different from the most common mu opioid receptor.

An endogenous opioid with wide distribution in both the CNS and the periphery, β- endoφhin has been postulated to play a role in diverse biological functions (25-27). As a neuropeptide, it can modulate neurotransmitter actions in the CNS to mediate antinociception. It is also a mediator in the stress response, of potential importance for the pathophysiology of the addictive diseases (28-36). β-endorphin can regulate the secretion of both stress and reproductive hormones, thereby influencing a variety of physiological functions. The synthesis and processing of β-endoφhin is, in turn, regulated by other factors, including certain neurotransmitters and hormones. Given the diverse roles of β- endorphin, it is particularly interesting that the A118G polymorphism may change both the binding affinity and functional potency of β-endorphin. On the basis of approximately three fold difference in the affinity and potency values (Fig. 2 and 3), it is possible that two individuals with different mu opioid receptors (most common vs. A118G variant) may show variation in β-endorphin sensitivity. This, in turn, could alter perception of pain. It also could alter the vulnerability to develop opioid addiction following exposure to opiates as well as addictions to other drugs that alter the opioid system (2,6,37).

Binding and functional studies on the C17T receptor have shown that β-endoφhin bound the C17T variant receptor less tightly than the prototype receptor. The average ratio of the IC₅₀ values was 0.72 for the variant:prototype receptor, indicating a modestly lower affinity for this ligand at the C17T variant receptor. This is in contrast to the higher affinity of β-endoφhin at the Al 18G variant receptor described above. One of the important indices of cellular functioning of the mu opioid receptor is the inhibition of adenylyl cyclase activity following agonist binding to the receptor. A modification of a previously described method (Chen,Y. , J.Liu, and L.Yu. 1996. Functional coupling of a mu opioid receptor to G proteins and adenylyl cyclase: modulation by chronic moφhine treatment. Addiction Biol. 1 :49-59) was used for measuring inhibition of adenylyl cyclase to reduce the amount of variability in the measurements. In this method, cells are replated 7 to 9 hours before the cyclase assay is conducted. This time is sufficient for the forskolin-stimulated cAMP levels and the percent inhibition by mu agonists to recover. The improvement in the intra-assay variability is most likely due to the fact that the number of cells in each well is the same, since there has been little time for the growth rates to diverge between wells. Using this modified method, adenylyl cyclase inhibition between the C17T and prototype receptors are compared (Fig. 6). We have found that the C17T receptor is less sensitive to β-endoφhin: the EC50 values differed by a factor of approximately 2.7. The receptor was also less sensitive to leu-enkephalin: the EC50 values differed by a factor of approximately 2.8.

METHODS

Study subjects and procedures

Addictive disease patients, specifically long-term heroin addicts currently m chronic methadone maintenance treatment, and normal control subjects with no history of any drug or alcohol abuse, were extensively characterized with respect to drug abuse, the addictive diseases, psychological and psychiatric profiles, and medical and ethnic family backgrounds Unrelated study subjects who were former heroin addicts were referred from methadone treatment clinics m the greater New York City area, primarily those associated with The Biology of Addictive Diseases Laboratory located at The Rockefeller University These clinics are the Adolescent Development Program and Adult Clinic at the New York Hospital-Cornell Medical Center Previously heroin-addicted patients admitted to the study conformed to the federally regulated criteria for admission to a methadone maintenance program, that is, one or more years of daily multiple-dose self-administration of heroin or other opiates with the development of tolerance, dependence, and drug-seeking behavior (38) Current or prior abuse of other drugs was not used as an exclusion criterion for this group as long as opioid abuse continued to be the primary diagnosis

Unrelated healthy volunteer subjects were recruited primarily through posting of notices and newspaper advertisements or referral by physicians or staff at the Rockefeller Univer- sity Hospital Individuals with continuing drug or alcohol abuse or prior extended periods of regular abuse were excluded from this category The exclusion criteria were defined as follows for current or continuing abuse, alcohol, at least five (for men) or four (for women) instances of drinking to intoxication during the previous 30 days, opiates, cocaine, amphetamines, or other illicit drugs (excluding cannabis), any use during the previous 30 days Users of nicotine or caffeine were not excluded, nor were individuals who had abused cannabis for up to 12 days during the previous 30 days For prior abuse, subjects were excluded who had abused illicit drugs, excluding cannabis, for at least three times a week for a period of at least one month All study subjects were rigorously screened to assure appropriate characterization of addictive diseases, status of treatment, and presence or absence of polydrug or alcohol abuse Subjects entering the study were required to be competent to understand the study procedures and understand and sign the Institutional Review Board approved informed consent Patients with schizophrenia or other psychotic mental illnesses were excluded from the study by this criterion The presence of serological markers for hepatitis B, C or HIV was not used as an exclusion criterion.

Both addictive disease patients and normal volunteers admitted to the study were assessed by a psychiatrist or research nurse with several psychiatric and psychological instruments as well as the Addiction Severity Index (39). Study subjects were also administered a detailed personal and medical and special addictive disease questionnaire as well as a family history medical and addictive disease questionnaire designed to provide information regarding substance abuse and major mental illness of first and second degree relatives. Study subjects provided detailed information regarding family origin and ethnic background, including country or geographic area of birth. This information was obtained for both the study subjects themselves and their immediate ancestors (parents, grandparents and great- grandparents), to the extent that the information was known by the study subjects. Study subjects were classified into five groups: African- American, Caucasian, Hispanic (Caribbean and Central or South American origin), Native North American, and Other. The detailed ancestral information collected by the family origin questionnaire allowed classification of study subjects into defined categories. Following psychiatric and behavioral assessment and informed consent and family history acquisition, venipuncture on the study subject was performed, and a blood specimen was taken. Blood samples were processed for DNA extraction and EBV transformation to create stable cell lines that were stored for future studies. All blood samples were coded; the psychiatrists and nurses who performed psychiatric and psychological assessments were blind to the genotypes of the study subjects, and the identity and categorization of the study subjects was unknown to the laboratory research personnel.

Exon amplification and sequencing

Sequences for the non-coding regions of the human mu opioid receptor gene were used to design PCR primers. PCR primers were synthesized for three of the four exons of the gene; the fourth exon was not included in this study because this exon is small (4 or 12 amino acid residues) and alternative splicing in this exon has been shown to occur (40). Exon 1 forward primer sequences were based on the 5 '-untranslated region of the receptor (9). Exon 1 reverse, exon 2 forward and reverse, and exon 3 forward primer sequences were based on partial intron sequence data obtained from inverse PCR of genomic DNA sequences for the receptor gene (data not shown). Exon 3 reverse primers were based on reported intron 3 sequence (40). Two sets of primers were designed for each exon to allow for nested PCR reactions to increase amplification specificity. Only one reverse primer was used for exon 1. The PCR reactions were performed with 300-400 ng of genomic DNA, PCR products were separated on agarose gels, and the DNA fragments were purified for DNA sequencing . DNA polymoφhisms were confirmed by both manual and automated sequencing.

Mutagenesis

In vitro site-directed mutagenesis was performed to generate human mu opioid receptor (hMOR) cDNA containing the A118G SNP. Complementary oligonucleotides containing the desired mutation were synthesized and annealed to the pcDNA3 plasmid containing the most common allelic form of hMOR. Primer 1 :

TTGTCCCACTTAGATGGCGACCTGTCCGACCCA (SEQ ID NO: 6). Primer 2: ACCGCATGGGTCGGACAGGTCGCCATCTAAGTG (SEQ ID NO: 7). Primers were extended and the product amplified by PCR using hMOR dsDNA as the template, and Dpn I restriction enzyme was added afterwards to digest the methylated, nonmutated most common dsDNA. After transformation into E. coli cells, DNA from individual colonies was examined by restriction enzyme digestion and DNA sequencing to confirm success of mutagenesis.

Cell Transfection and Binding Analysis

Stable transfection of the A118G SNP plasmid into AV-12 cells was performed as described (41). Individual colonies were then picked, expanded, and tested for expression levels by performing binding assays. Cells were harvested by washing with phosphate-buffered saline (PBS) at room temperature, then they were scraped into homogenization solution (0.3 M sucrose, 25 mM Tris-HCl, pH 7.4, 0.05 % BSA, and protease inhibitor cocktail, including 0.5 mM PMSF, 0.1 μg/ml leupeptin, and 0.01 % aprotinin), transferred to Dounce homogenizer and homogenized on ice. The suspension was centrifuged at 1,000 g for 10 min and the supernatant saved in a clean tube. The cell pellet was resuspended in homogenization buffer, homogenized and centrifuged as described above. The supernatants from both extractions were combined and centrifuged at 30,000 g for 20 min. The pelleted membranes were resuspended in binding buffer (50 mM Tris-HCl, pH 7.4), and binding assays were carried out using membrane protein preparations as described (9). Electrophysiology

Preparation of Xenopus oocytes was as previously reported (19). Oocytes were injected with in vitro transcribed mRNAs for the most common or A118G variant mu opioid receptors together with the G protein-activated inwardly rectifying K⁺ channels (GIRKl and GIRK2). Two to three days after RNA injection, oocytes were voltage-clamped in ND96 solution (96 mM NaCl, 2 mM KCl, 1 mM MgCl₂, 1.8 mM CaCl₂, 5 mM HEPES, pH 7.6) using a two-electrode voltage-clamp (Axon Instruments). Cells were then superfused with a high potassium solution (98 mM KCl, 1 mM MgCl₂, 1.8 mM CaCl₂, 5 mM HEPES, pH 7.6), and stimulated with opioid ligands to measure the resulting potassium current.

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The present invention is not to be limited in scope by the specific embodiments describe herein. Indeed, various modifications of the invention in addition to those described herein will become apparent to those skilled in the art from the foregoing description and the accompanying figures. Such modifications are intended to fall within the scope of the appended claims.

It is further to be understood that all base sizes or amino acid sizes, and all molecular weight or molecular mass values, given for nucleic acids or polypeptides are approximate, and are provided for description.

Various publications are cited herein, the disclosures of which are incoφorated by reference in their entireties.

Claims

WHAT IS CLAIMED IS 1 An isolated variant allele of a human mu opioid receptor gene, comprising a DNA sequence having a variation in SEQ ID NO 1 , wherein said variation comprises G24A, G779A, or G942A,

or combinations thereof

2 The isolated variant allele of Claim 1 , detectably labeled

3 The isolated variant allele of Claim 2, wherein said detectable label comprises a radioactive element, a chemical which fluoresces, or an enzyme

4 An isolated nucleic acid molecule hybridizable to said isolated variant allele of Claim 1 under standard hybridization conditions

5 The isolated nucleic acid molecule of Claim 4, detectably labeled

6 The isolated nucleic acid molecule of Claim 5, wherein said detectable label comprises a radioactive element, a chemical which fluoresces, or an enzyme

7 An isolated variant allele of a human mu opioid receptor gene which encodes a variant human mu opioid receptor comprising an amino acid sequence having a variation m SEQ ID NO 2, wherein said variation comprises Arg260H╬╣s

8 An isolated nucleic acid molecule hybridizable under standard hybridization conditions to an isolated variant allele of Claim 1 , wherein said isolated nucleic acid molecule encodes a variant human mu opioid receptor comprising an amino acid sequence having a variation in SEQ ID NO 2, wherein said variation comprises Arg260H╬╣s

9 A isolated variant human mu opioid receptor comprising an amino acid sequence having a variation in SEQ ID NO 2, wherein said variation comprises Arg260H╬╣s

10. An antibody having a variant human mu opioid receptor of Claim 9 as an immunogen.

11. The antibody of Claim 10, which is a polyclonal antibody.

12. The antibody of Claim 10, which is a monoclonal antibody.

13. The antibody of Claim 10, which is a chimeric antibody.

14. The antibody of Claim 10, detectably labeled

15. The antibody of Claim 14, wherein said detectable label comprises a radioactive element, a chemical which fluoresces, or an enzyme.

16. A cloning vector comprising an isolated variant allele of a human mu opioid receptor gene and an origin of replication, wherein said variant allele comprises a DNA sequence having a variation in SEQ ID NO: l , wherein said variation comprises: G24A; G779A; or G942A,

or combinations thereof.

17. A cloning vector comprising an origin of replication and an isolated nucleic acid molecule hybridizable under standard hybridization conditions to an isolated variant allele of a human mu opioid receptor gene, wherein said variant allele comprises a DNA sequence having at least one variation in SEQ ID NO: l , wherein said at least one variation comprises: G24A; G779A; or G942A,

or combinations thereof.

18. The cloning vector of either of Claims 16 or 17, wherein said cloning vector comprises of E. coli, bacteriophages, plasmids, or pUC plasmid derivatives.

19. The cloning vector of Claim 18, wherein bacteriophages further comprise lambda derivatives, plasmids further comprise pBR322 derivatives, and pUC plasmid derivatives further comprise pGEX vectors, or pmal-c, pFLAG.

20. An expression vector comprising an isolated variant allele of a human mu opioid receptor gene comprising a DNA sequence having a variation in SEQ ID NO: l , wherein said variation comprises:

G24A;

G779A; or

G942A,

or combinations thereof.

21. An expression vector comprising an isolated nucleic acid molecule hybridizable under standard hybridization conditions to an isolated variant allele of a human mu opioid receptor gene, wherein said isolated nucleic acid molecule is operatively associated with a promoter, and said variant allele comprises a DNA sequence having at least one variation in SEQ ID NO: l , wherein said at least one variation comprises:

G24A;

G779A; or

G942A, or combinations thereof.

22. The expression vector of either of Claims 20 or 21 , wherein said promoter comprises immediate early promoters of hCMV, early promoters of SV40, early promoters of adenovirus, early promoters of vaccinia, early promoters of polyoma, late promoters of SV40, late promoters of adenovirus, late promoters of vaccinia, late promoters of polyoma, the lac the trp system, the TAC system, the TRC system, the major operator and promoter regions of phage lambda, control regions of fd coat protein, 3-phosphoglycerate kinase promoter, acid phosphatase promoter, or promoters of yeast mating factor.

23. A unicellular host transformed or transfected with an expression vector comprising an isolated variant allele of a human mu opioid receptor gene operatively associated with a promoter, wherein said variant allele comprises a DNA sequence having at least one variation in SEQ ID NO: 1, wherein said at least one variation comprises: G24A; G779A; or G942A, or combinations thereof.

24. A unicellular host transformed with an expression vector comprising an isolated nucleic acid molecule hybridizable under standard hybridization conditions to an isolated variant allele of a human mu opioid receptor gene, wherein said isolated nucleic acid molecule is operatively associated with a promoter, and said variant allele comprises a DNA sequence having at least one variation in SEQ ID NO: l , wherein said at least one variation comprises: G24A; G779A; or G942A, or combinations thereof.

25. The unicellular host of either of Claims 23 or 24, wherein said host comprises E. coli, Pseudomonas, Bacillus, Streptomyces. yeast, CHO, Rl. l , B-W, L-M, COSl , COS7, BSCl , BSC40, BMT10 or Sf9 cells.

26. A method of producing an a variant human mu opioid receptor comprising an amino acid sequence having a variation in SEQ ID NO:2, wherein said variation comprises Arg260His, said method comprising the steps of: a) culturing a unicellular host of either of Claims 23 or 24 under conditions that provide for expression of said variant human mu opioid receptor; and b) recovering said variant human mu opioid receptor from said unicellular host.

27. An isolated variant allele of a human mu opioid receptor gene, wherein said variant allele comprises a DNA sequence having at least two variations in SEQ ID NO: 1 , wherein said variations comprise: A118G; C17T; G24A; G779A; or G942A.

28. The isolated variant allele of Claim 27, detectably labeled.

29. The isolated variant allele of Claim 28, wherein said detectable label comprises a radioactive element, a chemical which fluoresces, or an enzyme.

30. An isolated nucleic acid molecule hybridizable under standard hybridization conditions to an isolated variant allele of a human mu opioid receptor gene comprising a DNA sequence having at least two variations in SEQ ID NO: l , wherein said variations comprise: A118G; C17T; G24A; G779A; or G942A.

31. The isolated nucleic acid molecule of Claim 30, detectably labeled.

32. The isolated nucleic acid molecule of Claim 31 , wherein said detectable label comprises a radioactive element, a chemical which fluoresces, or an enzyme.

33. An isolated variant allele of a human mu opioid receptor gene, which encodes a variant human mu opioid receptor comprising an amino acid sequence having at least two variations in SEQ ID NO:2, wherein said variations comprise: Asn40Asp; Ala╧îVal; or Arg260His.

34 An isolated nucleic acid molecule hybridizable under standard hybridization conditions to an isolated variant allele of a human mu opioid receptor gene, wherein and said va╧Çant allele comprises a DNA sequence having at least two variations in SEQ ID NO 1 , and said variations comprise A118G, C17T, G24A, G779A, or G942A,

so that said isolated nucleic acid molecule encodes a variant human mu opioid receptor comprising at least two variations m sequence of SEQ ID NO 2, wherein said variations comprise Asn40Asp, Ala╧îVal, or Arg260H╬╣s

35 A variant human mu opioid receptor comprising an amino acid sequence having at least two variations in SEQ ID NO 2, wherein said variations comprise Asn40Asp, Ala╧îVal, or Arg260H╬╣s

36 An antibody having a variant human mu opioid receptor of Claim 35 as an immunogen

37 The antibody of Claim 36, which is a polyclonal antibody

38 The antibody of Claim 36, which is a monoclonal antibody

39 The antibody of Claim 36, which is a chimeric antibody

40 The antibody of Claim 36, detectably labeled

10-

41. The antibody of Claim 40, wherein said detectable label comprises a radioactive element, a chemical which fluoresces, or an enzyme.

42. A cloning vector comprising an isolated variant allele of a human mu opioid receptor gene and an origin of replication, wherein said variant allele comprises a DNA sequence having at least two variations in SEQ ID NO: l, wherein said variations comprise: A118G; C17T; G24A; G779A; or G942A. ^Γû║

43. A cloning vector comprising an origin of replication and an isolated nucleic acid molecule hybridizable under standard hybridization conditions to an isolated variant allele of a human mu opioid receptor gene, wherein said variant allele comprises a DNA sequence having at least two variations in SEQ ID NO:l, wherein said variations comprise:

A118G;

C17T;

G24A;

G779A; or

G942A.

44. The cloning vector of either of Claims 42 or 43, wherein said cloning vector comprises E. coli, bacteriophages, plasmids, or pUC plasmid derivatives.

45. The cloning vector of Claim 44, wherein bacteriophages further comprise lambda derivatives, plasmids further comprise pBR322 derivatives, pUC plasmid derivatives further comprise pGEX vectors, or pmal-c, pFLAG.

46. An expression vector comprising an isolated variant allele of a human mu opioid receptor gene operatively associated with a promoter, wherein said variant allele comprises a DNA sequence having at least two variations in SEQ ID NO: 1, wherein said variations comprise: A118G; C17T; G24A;

G779A; or

G942A.

47. An expression vector comprising an isolated nucleic acid molecule hybridizable under standard hybridization conditions to an isolated variant allele of a human mu opioid receptor gene, wherein said isolated nucleic acid molecule is operatively associated with a promoter, and said variant allele comprises a DNA sequence having at least two variations in SEQ ID NO: l , wherein said variations comprise: A118G; C17T; G24A; G779A; or G942A.

48. The expression vector of either of Claims 46 or 47, wherein said promoter comprises immediate early promoters of hCMV, early promoters of SV40, early promoters of adenovirus, early promoters of vaccinia, early promoters of polyoma, late promoters of SV40, late promoters of adenovirus, late promoters of vaccinia, late promoters of polyoma, the lac the trp system, the TAC system, the TRC system, the major operator and promoter regions of phage lambda, control regions of fd coat protein, 3-phosphoglycerate kinase promoter, acid phosphatase promoter, or promoters of yeast mating factor.

49. A unicellular host transformed with an expression vector of Claim 46.

50. A unicellular host transformed with an expression vector of Claim 47.

51. The unicellular host of either of Claims 49 or 50, wherein said host comprises E. coli, Pseudomonas, Bacillus, Streptomyces, yeast, CHO, Rl . l , B-W, L-M, COSl, COS7, BSCl , BSC40 , BMT 10 or Sf 9 cells .

52. A method for producing a variant human mu opioid receptor comprising an amino acid sequence having at least two variations in SEQ ID NO: 2, wherein said variations comprise: Asn40Asp; Ala╧îVal; or Arg260His, wherein the method comprising the steps of: a) culturing a unicellular host of either of Claims 49 or 50 under conditions that provide for expression of said variant human mu opioid receptor; and b) recovering said variant human mu opioid receptor from said unicellular host.

53. A method for determining a susceptibility in a subject to at least one addictive disease, comprising the steps of: a) removing a bodily sample from said subject, wherein said sample comprises a first and second allele comprising a human mu opioid receptor gene; b) determining whether said human mu opioid receptor gene of said first allele comprises a DNA sequence having at least one variation in SEQ ID NO: l, wherein said variation comprises: A118G; or C17T,

such that the presence of said at least one variation in said human mu opioid receptor gene of said first allele is expected to be indicative of the subject's susceptibility to at least one addictive disease relative to the susceptibility to said at least one addictive disease in a standard.

54. The method for determining a susceptibility to at least one addictive disease of Claim 53, further comprising the step of determining whether said human mu opioid receptor gene of said second allele comprises a DNA sequence having at least one variation in SEQ ID NO: 1 , wherein said variation comprises: A118G; or C17T,

such that the presence of said at least one variation in said human mu opioid receptor gene of said second allele is expected to be indicative of the subject's susceptibility to said at least one addictive disease relative to the susceptibility to said at least one addictive disease in said standard.

13-

55. The method of either of Claims 53 or 54, wherein said at least one variation of said human mu opioid receptor gene of said first and/or second allele comprises Al 18G, and said variation is expected to be indicative of a decreased susceptibility to said at least one addictive disease in the subject relative to the susceptibility to said at least one addictive disease in the standard.

56. The method of either of Claims 54 or 55, wherein said at least one addictive disease comprises: opioid addiction; cocaine addiction or addiction to other psychostimulants; nicotine addiction; barbituate or sedative hypnotic addiction; anxiolytic addiction; or alcohol addiction.

57. The method of either of Claims 53 or 54, wherein where said at least one variation of said human mu opioid receptor gene of said first and/or second allele comprises C17T, and said variation is expected to be indicative of an increased susceptibility to said at least one addictive disease in said subject relative to susceptibility to said at least one addictive disease in said standard.

58. The method of Claim 57, wherein said at least addictive disease comprises: opioid addiction; cocaine addiction or addiction to other psychostimulants; nicotine addiction; barbituate or sedative hypnotic addiction; anxiolytic addiction; or alcohol addiction.

59. A method for determining a susceptibility to at least one addictive disease in a subject relative to susceptibility m a standard, comprising the steps of a) removing a bodily sample from said subject, wherein said sample comprises a human mu opioid receptor, b) determining whether said human mu opioid receptor comprises an ammo acid sequence having at least one variation m SEQ ID NO 2, wherein said variation comprises Asn40Asp, or Ala╧îVal, such that the presence of said at least one variation is expected to be indicative of the susceptibility to said at least one addictive disease in said subject relative to susceptibility to said at least one addictive disease in said standard, wherein the human mu opioid receptor of said standard comprises an ammo acid sequence of SEQ ID NO 2

60 The method of Claim 59, wherein said at least one variation m SEQ ID NO 2 comprises Asn40Asp, and is expected to be indicative of a decreased susceptibility to said at least one addictive disease in said subject relative to said susceptibility to said at least one addictive disease in said standard, wherein the human mu opioid receptor of said standard comprises an ammo acid sequence of SEQ ID NO 2

61 The method of Claim 59, wherein said at least one variation in SEQ ID NO 2 comprises Ala╧îVal, and is expected to be indicative of an increased susceptibility to said at least one addictive disease m said subject relative to susceptibility to said at least one addictive disease in said standard, wherein said human mu opioid receptor of said standard comprises an amino acid sequence of SEQ ID NO 2

62 The method of either of Claims 60 or 61, wherein said at least one addictive disease comprises opioid addiction, cocaine addiction or addiction to other psychostimulants, nicotine addiction, barbituate or sedative hypnotic addiction, anxiolytic addiction, or alcohol addiction

63 A method for determining a susceptibility to pain in a subject relative to a suscepti- bihty of pam in a standard, wherein the method comprises the steps of a) removing a bodily sample from said subject, wherein said sample comprises a first and second allele comprising a human mu opioid receptor gene, b) determining whether said human mu opioid receptor gene of said first allele comprises a DNA sequence having at least one variation in SEQ ID NO 1 , wherein said variation comprises A118G, er C17T,

such that the presence of said at least one variation in said human mu opioid receptor gene of said first allele is expected to be indicative of susceptibility to pain in said subject relative to susceptibility to pain m said standard, wherein said first allele of said standard comprises a human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO 1

64 The method of Claim 63 for determining a susceptibility to pain in a subject, further comprising the step of determining whether said second allele of said bodily sample comprises a human mu opioid receptor gene comprising a DNA sequence having at least one variation in SEQ ID NO 1 , wherein said variation comprises A118G, or C17T,

such that the presence of said at least one variation in said second allele is expected to be indicative of susceptibility to pain in said subject relative to susceptibility of pain in said standard, wherein said second allele of said standard comprises a human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO 1

65 The method of either of Claims 63 or 64, wherein where said at least one variation in said human mu opioid receptor gene of said first and/or second allele of said bodily sample from said subject comprises Al 18G, wherein said variation is expected to be indicative of a decreased susceptibility to pain in said subject relative to susceptibility to

16- pam m said standard

66 The method of either of Claims 63 or 64, wherein where said at least one variation in said human mu opioid receptor gene of said first and/or second allele of said bodily sample from said subject comprises C17T, wherein said variation is expected to be indicative of an increased susceptibility to pain m subject relative to said susceptibility to pain in said standard

67 A method for determining a therapeutically effective amount of pain reliever to administer to a subject in order to induce analgesia in said subject relative to a therapeuti- cally effective amount of pain reliever to administer to a standard in order to induce analgesia in said standard, wherein the method comprises determining a susceptibility to pam in said subject relative to susceptibility to pain m said standard, wherein susceptibility to pam in said subject is expected to be indicative of said therapeutically effective amount of pain reliever to administer to said subject to induce analgesia in said subject relative to said therapeutically effective amount of pam reliever to administer to said standard to induce analgesia in said standard

68 The method of Claim 67 for determining a therapeutically effective amount of pain reliever to administer to said subject, wherein determining susceptibility to pain in said subject comprises the steps of a) removing a bodily sample from said subject, wherein said sample comprises a first and second allele comprising a human mu opioid receptor gene, and b) determining whether said first allele comprises a human mu opioid receptor gene comprising a DNA sequence having at least one variation in SEQ ID NO 1 , wherein said at least one variation comprises A118G, or C17T,

wherein the presence of said at least one variation in said human mu opioid receptor gene of said first allele is expected to be indicative of the subject's susceptibility to pain relative to said to susceptibility of pain in said standard, wherein said first allele of said standard comprises a human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO 1 , such that said therapeutically effective amount of pain reliever to administer to the subject in order to induce analgesia is related to said susceptibility to pain in said subject relative to susceptibility to pain in said standard.

69. The method of Claim 68, wherein determining susceptibility to pain in said subject relative to susceptibility to pain in said standard further comprises the step of determining whether said second allele of said bodily sample from said subject comprises a human mu opioid receptor gene comprising a DNA sequence having at least one variation in SEQ ID NO: 1 , wherein said at least one variation comprises:

C17T,

such that the presence of said at least one variation in said second allele is expected to be indicative of susceptibility to pain in said subject relative to susceptibility to pain in said standard, wherein said second allele of said standard comprises a human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO: l , and the therapeutically effective amount of pain reliever to administer to said subject to induce analgesia in said subject is related to the presence of said at least one variation in said human mu opioid receptor gene of said second allele of said bodily sample from said subject.

70. The method of either of Claims 68 or 69, wherein said at least one variation in said human mu opioid receptor gene of said first and/or second allele of said bodily sample comprises Al 18G, and said variation is expected to be indicative of an decreased suscepti- bility to pain in said subject relative to susceptibility to pain in said standard, and expected to be indicative of a decreased therapeutically effective amount of pain reliever to adminis- ter to said subject to induce analgesia in said subject relative to said therapeutically effective amount of pain reliever to administer to said standard to induce analgesia in said standard.

71. The method of determining the therapeutically effective amount of pain reliever to administer to a subject of either of Claims 68 or 69, wherein said at least one variation in said human mu opioid receptor gene of first and/or second allele of said bodily sample comprises C17T, wherein said variation is expected to be indicative of an increased susceptibility to pain in said subject relative to susceptibility of pain in the standard, and is expected to be indicative of an increased therapeutically effective amount of pain reliever to administer to the subject to induce analgesia in the subject relative to the therapeutically effective amount of pain reliever to induce analgesia in the standard.

72. A method for determining a therapeutically effective amount of therapeutic agent to administer to a subject suffering from at least one addictive disease to treat the at least one addictive disease in said subject relative to a therapeutically effective amount of therapeutic agent to administer to a standard suffering from the at least one addictive disease to treat the at least one addictive disease in said standard, wherein the method comprises the steps of: a) removing a bodily sample from said subject, wherein said sample comprises a first and second allele comprising a human mu opioid receptor gene; and b) determining whether said first allele comprises a human mu opioid receptor gene comprising a DNA sequence having at least one variation in SEQ ID NO: l , wherein said variation comprises: A118G; or C17T, wherein the presence of said at least one variation in said human mu opioid receptor gene of said first allele is expected to be indicative of the therapeutically effective amount of said therapeutic agent to administer to the subject to treat said at least one addictive disease in said subject relative to said therapeutically effective amount of said therapeutic agent to administer to said standard to treat said at least one addictive disease in said standard, wherein said first allele of said standard comprises a human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO: 1.

73. The method of Claim 72 for determining a therapeutically effective amount of therapeutic agent to administer to a subject suffering from said at least one addictive disease to treat said at least one addictive disease, relative to said therapeutically effective amount of said therapeutic agent administered to said standard suffering from said at least one addictive disease to treat said at least one addictive disease in said standard, further comprising the step of determining whether said second allele of said bodily sample from said subject comprises a human mu opioid receptor gene comprising a DNA sequence having at least one variation in SEQ ID NO: 1, wherein said variation comprises: A118G; or C17T,

such that the presence of said at least one variation in said second allele related to said therapeutically effective amount of said therapeutic agent administered to said subject to treat said at least one addictive disease in said subject relative to said therapeutically effective amount of said therapeutic agent to administer to said standard to treat said at least one addictive disease in said standard, wherein said second allele of said standard comprises a human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO: 1.

74. The method of either of Claims 72 or 73, wherein said at least one variation in said human mu opioid receptor gene of said first and/or second allele of the bodily sample comprises Al 18G, and said variation is expected to be indicative of an decreased therapeu- tically effective amount of said therapeutic agent to administer to said subject suffering said at least one addictive disease to treat said at least one addictive disease in said subject, relative to said therapeutically effective amount of said therapeutic agent to administer to said standard suffering from said at least one addictive disease to treat said at least one addictive disease in said standard, wherein either or both alleles of said standard comprise a human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO: 1.

75. The method of either of Claims 72 or 73 for determining a therapeutically effective amount of therapeutic agent to administer to a subject suffering from said at least one addictive disease to treat said at least one addictive disease, wherein said at least one variation in said human mu opioid receptor gene of said first and/or second allele comprises C17T, and said variation is expected to be indicative of an increased therapeutically effective amount of said therapeutic agent to administer to said subject suffering said at least one addictive disease to treat said at least one addictive disease in said subject, relative to said therapeutically effective amount of said therapeutic agent to administer to said standard suffering from said at least one addictive disease to treat said at least one addictive disease in said standard, wherein either or both alleles of said standard comprise a human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO: 1.

76. The method of either of Claims 72 or 73, wherein said at least one addictive disease comprises: opioid addiction; cocaine addiction or addiction to other psychostimulants; nicotine addiction; barbiturate or sedative hypnotic addiction; anxiolytic addiction; or alcohol addiction.

77. A commercial test kit may for determining the presence of at least one variation in a human mu opioid receptor gene of an allele in a bodily sample taken from a subject, wherein the commercial test kit comprises: a) PCR oligonucleotide primers suitable for detection of an allele comprising a human mu opioid receptor gene comprising a DNA sequence having a variation in SEQ ID NO : 1 ; b) other reagents; and c) directions for use of the kit.

78. A commercial test kit for detecting a variant human mu opioid receptor in a bodily sample taken from a subject, comprising a predetermined amount of at least one detectably labeled immunochemically reactive component having affinity for a variant human mu opioid receptor; (b) other reagents; and (c) directions for use of the kit.

79. A commercial test kit for detecting a variant human mu opioid receptor in a bodily sample taken from a subject, wherein said kit comprises: (a) a labeled component which has been obtained by coupling the human mu opioid receptor of the bodily sample to a detectable label; (b) one or more additional immunochemical reagents of which at least one reagent is a ligand or an immobilized ligand, which ligand comprises: (i) a ligand capable of binding with the labeled component (a); (ii) a ligand capable of binding with a binding partner of the labeled component (a); (iii) a ligand capable of binding with at least one of the component(s) to be determined; or (iv) a ligand capable of binding with at least one of the binding partners of at least one of the component(s) to be determined; (c) directions for the performance of a protocol for the detection and/or determination of one or more components of an immunochemical reaction between the human mu opioid receptor and a specific binding partner thereto.

80. A methorJ for diagnosing a disease or disorder related to a physiological function regulated by the hypothalamus pituitary adrenal axis (HPA) or the hypothalamus pituitary gonadal axis (HPG), wherein the method comprises the steps of: a) removing a bodily sample from said subject, wherein said sample comprises a first and second allele comprising a human mu opioid receptor gene: b) determining whether said human mu opioid receptor gene of said first allele comprises a DNA sequence having at least one variation in SEQ ID NO: l , wherein said variation comprises: A118G; or C17T,

such that the presence of said at least one variation in said human mu opioid receptor gene of said first allele is expected to be indicative of a disease or disorder related to a physiological function regulated by the hypothalamus pituitary adrenal axis (HPA) or the hypothala- mus pituitary gonadal axis (HPG), wherein said first allele of said standard comprises a human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO: 1.

81. The method of Claim 80, wherein said physiological function comprises sexual or reproductive function, gastrointestinal motility, immune response, or ability to withstand stress.

82. The method of Claim 81 , wherein said disease or disorder comprises infertility, constipation, diarrhea, decreased immune response relative to said standard, or decreased ability to withstand stress relative to said standard.

83. The method of Claim 80 for diagnosing a disease or disorder related to a physiological function regulated by the HPA or HPG, further comprising the step of determining whether said second allele of said bodily sample comprises a human mu opioid receptor gene comprising a DNA sequence having at least one variation in SEQ ID NO: l , wherein said variation comprises: A118G; or C17T,

such that the presence of said at least one variation in said second allele is expected to be indicative of a disease or disorder related to a physiological function regulated by the HPA or HPG axes, wherein said second allele of said standard comprises a human mu opioid receptor gene comprising a DNA sequence of SEQ ID NO: 1.

84. The method of Claim 83, wherein said physiological function comprises sexual or reproductive function, gastrointestinal motility, immune response, or ability to withstand stress .

85. The method of Claim 83, wherein said disease or disorder comprises infertility, constipation, diarrhea, decreased immune response relative to said standard, or decreased ability to withstand stress relative to said standard.

86. The method of either of Claims 80 or 82, wherein where said at least one variation in said human mu opioid receptor gene of said first and/or second allele of said bodily sample from said subject comprises A118G, wherein said variation is expected to be indicative of a disease or disorder related decreased activity of said HPA or HPG axes.

87. The method of Claim 86, wherein said disease or disorder comprises diarrhea.

88. The method of either of Claims 80 or 83, wherein where said at least one variation in said human mu opioid receptor gene of said first and/or second allele of said bodily sample from said subject comprises C17T, wherein said variation is expected to be indicative of a disease or disorder related to increased HPA or HPG activity in said subject relative to said activity in said standard.

89. The method of Claim 88, wherein said disease or disorder comprises infertility, constipation, decreased immune response relative to said standard, or decreased ability to withstand stress relative to said standard.

90. A method for selecting an appropriate therapeutic agent and a therapeutically effective amount of said agent to administer to said subject to treating a disease or disorder related to a physiological function regulated by the HPA or HPG axes, wherein the method comprises diagnosing said disease or disorder in said subject, wherein said disease or disorder is expected to be indicative of said appropriate therapeutic agent for treating said disease or disorder.

91. The method of Claim 90, wherein said physiological function comprises reproduc- tive or sexual function, gastrointestinal motility, immune response, or ability to withstand stress.

92. The method of Claim 90, wherein diagnosing said disease or disorder in said subject comprises the steps of: a) removing a bodily sample from said subject, wherein said sample comprises a first and second allele comprising a human mu opioid receptor gene; and b) determining whether said first allele comprises a human mu opioid receptor gene comprising a DNA sequence having at least one variation in SEQ ID NO: l , wherein said at least one variation comprises: A118G; or C17T,

wherein the presence of said at least one variation in said human mu opioid receptor gene of said first allele is expected to be indicative of said disease or disorder related to a physiolog- ical function regulated by the HPA or HPG axes.

93. The method of Claim 92, wherein diagnosing a disease or disorder related to a physiological function regulated by the HPA or HPG further comprises the step of deter- mining whether said second allele of said bodily sample comprises a human mu opioid receptor gene comprising a DNA sequence having at least one variation in SEQ ID NO: 1, wherein said variation comprises: A118G; or C17T,

94. The method of Claim 93, wherein said physiological function comprises reproduc- tive or sexual function, gastrointestinal motility, immune response, or ability to withstand stress.

95. The method of Claim 94, wherein said disease or disorder comprises infertility, constipation, diarrhea, decreased immune response relative to immune response in said standard, or decreased ability to withstand stress relative to ability to withstand stress of said standard.

96. The method of either of Claims 90 or 92, wherein said at least one variation in said human mu opioid receptor gene of said first and/or second allele of said bodily sample comprises Al 18G, and said variation is expected to be indicative of an a disease or disorder related to decreased HPA or HPG axis activity.

97. The method of Claim 96, wherein said disease or disorder comprises diarrhea.

98. The method of either of Claims 90 or 92, wherein said at least one variation in said human mu opioid receptor gene of first and/or second allele of said bodily sample com- prises C17T, wherein said variation is expected to be indicative of an a disease or disorder related to increased activity of said HPA or HPG axes.

-12f

99. The method of Claim 98, wherein said disease or disorder comprises infertility, constipation, decreased immune response relative to immune response in said standard, or decreased ability to withstand stress relative to ability to withstand stress of said standard.