EP4689117A1

EP4689117A1 - Therapeutic strategy for pcdh19-related encephalopathy

Info

Publication number: EP4689117A1
Application number: EP24781953.5A
Authority: EP
Inventors: Xiaoyu Chen; Sergiu P. PASCA
Original assignee: Leland Stanford Junior University
Current assignee: Leland Stanford Junior University
Priority date: 2023-03-31
Filing date: 2024-03-28
Publication date: 2026-02-11
Also published as: WO2024206668A1; AU2024245158A1

Abstract

Provided herein are methods of treating an individual having PCHD19-related condition, the methods including administering an effective dose of an agent to the individual, wherein the agent modulates the expression of a PCDH19 gene product. Also provided are compositions finding use in embodiments of the methods.

Description

THERAPEUTIC STRATEGY FOR PCDH19-RELATED ENCEPHALOPATHY

GOVERNMENT RIGHTS

[0001] This invention was made with Government support under contract MH1 15012 awarded by the National Institutes of Health. The Government has certain rights in the invention.

CROSS REFERENCE TO RELATED APPLICATIONS

[0002] Pursuant to 35 U.S.C. § 119 (e), this application claims priority to the filing date of United States Provisional Patent Application Serial No. 63/456,303 filed March 31 , 2023, the disclosure of which application is herein incorporated by reference.

REFERENCE TO AN ELECTRONIC SEQUENCE LISTING

[0003] The contents of the electronic sequence listing (STAN-2087WO_Seq_List.xml; Size: 31 ,154 bytes; and Date of Creation: March 18, 2024) is herein incorporated by reference in its entirety.

INTRODUCTION

[0004] Variants in the X-linked gene PCDH19 are associated with autism spectrum disorder (ASD), and loss of function variants cause a severe encephalopathy characterized by epileptic seizures and ASD (SFARI scoring: S). PCDH19-related encephalopathy is associated with ASD in up to 60% of cases and represents the second most clinically relevant genetic form of epilepsy after mutations in the sodium channel gene SCN1A. PCDH19-related disorders show an intriguing, unique pattern of inheritance: hemizygous males are not affected although they completely lack the PCDH19 protein, while heterozygous females are almost always severely affected [7, 10]. This is thought to be related to X-chromosome inactivation during development and subsequent mosaic tissue expression of PCDH19 in females.

SUMMARY

[0005] The inventors have realized that, during forebrain development, the presence of PCDH19 in some cells but not its complete absence leads to disrupted cell-cell interaction and deleterious neural phenotypes. This has led the inventors to the understanding that removing PCHD19 completely may represent a therapeutic strategy in patients.

[0006] Provided herein are methods, compositions, and kits directed to the treatment of PCDH19-related encephalopathy. Provided herein are methods of treating an individual having PCHD19-related condition, the methods including administering an effective dose of an agent to the individual, wherein the agent leads to the significant reduction of PCDH19 gene and protein expression.

[0007] Compositions and kits for practicing the subject methods are provided.

[0008] These and other objects, advantages, and features of the invention will become apparent to those persons skilled in the art upon reading the details of the subject methods and compositions as more fully described below.

BRIEF DESCRIPTION OF THE DRAWINGS

[001] The invention is best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not to-scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. Included in the drawings are the following figures.

[0009] FIGs. 1 A-1 F. Screening of ASOs targeting the PCDH19 Qene. FIG.1 A. Schematic of PCDH19 gene and mRNA. FIG. 1 B. ASO composition FIG. 1 C. Experimental design for the ASO screen. FIG. 1 D. The RT-qPCR assay to assess the screen. hCO were dissociated and plated. 5 pM of each ASO was added. Data are mean ± SEM. FIG. 1 E. Validation of ASO efficacies in the hCOs. 5 pM of each ASO was added. Data are mean ± SEM FIG. 1 F. RT- qPCR of ASO treated hCOs. Forward and reverse primers are in exon 1 and exon 2 of the PCDH19 gene.

[002] The invention is best understood from the following detailed description when read in conjunction with the accompanying drawings.

DEFINITIONS

[0010] Before describing exemplary embodiments in greater detail, the following definitions are set forth to illustrate and define the meaning and scope of the terms used in the description.

[001 1] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Singleton, et al., DICTIONARY OF MICROBIOLOGY AND MOLECULAR BIOLOGY, 2D ED., John Wiley and Sons, New York (1994), and Hale & Markham, THE HARPER COLLINS DICTIONARY OF BIOLOGY, Harper Perennial, N.Y. (1991 ) provide one of skill with the general meaning of many of the terms used herein. Still, certain terms are defined below for the sake of clarity and ease of reference.

[0012] Certain ranges are presented herein with numerical values being preceded by the term "about." The term "about" is used herein to provide literal support for the exact number that it precedes, as well as a number that is near to or approximately the number that the term precedes. In determining whether a number is near to or approximately a specifically recited number, the near or approximating unrecited number may be a number which, in the context in which it is presented, provides the substantial equivalent of the specifically recited number. [0013] It must be noted that as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. For example, the term “an agent” refers to one or more agents, i.e., a single agent and multiple agents. It is further noted that the claims can be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as “solely,” “only” and the like in connection with the recitation of claim elements, or use of a “negative” limitation.

[0014] All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications are cited. It is understood that the present disclosure supersedes any disclosure of an incorporated publication to the extent there is a contradiction.

[0015] The terms “polynucleotide” and “nucleic acid,” used interchangeably herein, refer to a polymeric form of nucleotides of any length, either ribonucleotides or deoxynucleotides. Thus, this term includes, but is not limited to, single-, double-, or multi-stranded DNA or RNA, genomic DNA, cDNA, DNA-RNA hybrids, or a polymer containing purine and pyrimidine bases or other natural, chemically or biochemically modified, non-natural, or derivatized nucleotide bases. The terms “polynucleotide” and “nucleic acid” should be understood to include, as applicable to the embodiment being described, single-stranded (such as sense or antisense) and double-stranded polynucleotides.

[0016] By "hybridizable" or “complementary” or “substantially complementary" it is meant that a nucleic acid (e.g. RNA, DNA) has a sequence of nucleotides that enables it to non-covalently bind, i.e. form Watson-Crick base pairs and/or G/U base pairs, “anneal”, or “hybridize,” to another nucleic acid in a sequence-specific, antiparallel, manner (i.e., a nucleic acid specifically binds to a complementary nucleic acid) under the appropriate in vitro and/or in vivo conditions of temperature and solution ionic strength. Standard Watson-Crick base-pairing includes: adenine/adenosine) (A) pairing with thymidine/thymidine (T), A pairing with uracil/ uridine (U), and guanine/guanosine) (G) pairing with cytosine/cytidine (C). In addition, for hybridization between two RNA molecules (e.g., dsRNA), and for hybridization of a DNA molecule with an RNA: G can also base pair with U. For example, G/U base-pairing is partially responsible for the degeneracy (i.e., redundancy) of the genetic code in the context of tRNA anti-codon base-pairing with codons in mRNA. Thus, in the context of this disclosure, a G (e.g., of a protein-binding segment (e.g., dsRNA duplex) of an RNA molecule; is considered complementary to both a U and to C. For example, when a G/U base-pair can be made at a given nucleotide position of a protein-binding segment (e.g., dsRNA duplex) of an RNA molecule, the position is not considered to be non-complementary, but is instead considered to be complementary.

[0017] Hybridization requires that the two nucleic acids contain complementary sequences, although mismatches between bases are possible. The conditions appropriate for hybridization between two nucleic acids depend on the length of the nucleic acids and the degree of complementarity, variables well known in the art. The greater the degree of complementarity between two nucleotide sequences, the greater the value of the melting temperature (Tm) for hybrids of nucleic acids having those sequences. Typically, the length for a hybridizable nucleic acid is 8 nucleotides or more (e.g., 10 nucleotides or more, 12 nucleotides or more, 15 nucleotides or more, 20 nucleotides or more, 22 nucleotides or more, 25 nucleotides or more, or 30 nucleotides or more).

[0018] It is understood that the sequence of a polynucleotide need not be 100% complementary to that of its target nucleic acid to be specifically hybridizable. Moreover, a polynucleotide may hybridize over one or more segments such that intervening or adjacent segments are not involved in the hybridization event (e.g., a loop structure or hairpin structure, a ‘bulge’, and the like). A polynucleotide can include 60% or more, 65% or more, 70% or more, 75% or more, 80% or more, 85% or more, 90% or more, 95% or more, 98% or more, 99% or more, 99.5% or more, or 100% sequence complementarity to a target region within the target nucleic acid sequence to which it will hybridize. For example, an antisense nucleic acid in which 18 of 20 nucleotides of the antisense compound are complementary to a target region, and would therefore specifically hybridize, would represent 90 percent complementarity. The remaining noncomplementary nucleotides may be clustered or interspersed with complementary nucleotides and need not be contiguous to each other or to complementary nucleotides. Percent complementarity between particular stretches of nucleic acid sequences within nucleic acids can be determined using any convenient method. Example methods include BLAST programs (basic local alignment search tools) and PowerBLAST programs (Altschul et al., J. Mol. Biol., 1990, 215, 403-410; Zhang and Madden, Genome Res., 1997, 7, 649-656) or by using the Gap program (Wisconsin Sequence Analysis Package, Version 8 for Unix, Genetics Computer Group, University Research Park, Madison Wis.), e.g., using default settings, which uses the algorithm of Smith and Waterman (Adv. Appl. Math., 1981 , 2, 482- 489).

[0019] The terms "peptide," "polypeptide," and "protein" are used interchangeably herein, and refer to a polymeric form of amino acids of any length, which can include coded and noncoded amino acids, chemically or biochemically modified or derivatized amino acids, and polypeptides having modified peptide backbones.

[0020] The term “neural organoid” as used herein refers to a range of brain-region specific organoids. Neural organoids encompass any organoid that contains neurons from any part of the brain. Cortical organoids, midbrain organoids, striatal organoids, spinal cord/hindbrain, ventral forebrain organoids, and organoids having any combination of the aforementioned organoids are encompassed by the term neural organoids.

[0021] PCDH19-related encephalopathy (Also known as Epilepsy and Mental Retardation Limited to Females, EFMR, or Developmental and Epileptic Encephalopathy 9, DEE9) was first described in 1971 by Juberg and Hellman as an early onset seizure disorder triggered by febrile illness, and with female-limited expression. The causative gene was identified in 2008 by Dibbens et al. in a study that involved six new EFMR families, as well as the original EFMR family reported by Juberg and Helman. In the same year, EFMR was further characterized as a neurological disorder with a markedly varied neuropsychiatric profile including intellectual disability (ID), and aggressive, ASD related, or obsessive features. In 2009, Depienne et al. identified PCDH19 mutations in sporadic cases with infantile development and epileptic encephalopathy resembling Dravet syndrome. Males have been identified who are cellular mosaics for the PCDH19 gene with a similar clinical profile as that of affected females, thus challenging the dogma that this is a disorder limited exclusively to females. The hallmark feature of PCDH19-associated epilepsy is that seizures occur in clusters. Seizures typically present as generalized tonic-clonic and/or focal seizures, which may evolve to bilateral, tonic- clonic seizures. An additional unifying feature of PCDH19-related encephalopathy is cellular mosaicism, either due to X-chromosome inactivation in females or early somatic mutation and, as such, somatic mosaicism in males.

[0022] PCDH19-related encephalopathy is associated with a reduction or remission of seizures during adolescence. Unfortunately, neuropsychiatric dysfunction remains, often exacerbating with age and becoming the most prominent and disabling feature in some patients. ID ranging from mild to profound is present in approximately 70% of the cases. The prevalence of psychiatric comorbidities is unknown; however, reports suggest that ASD is a common feature in both females and males. I ntriguingly , no association has been established between the severity of epilepsy and ID. PCDH19-related encephalopathy has been described by, for example, Kolc et al. (Mol Psychiatry. 2019 Feb;24(2):241 -251 ), which is specifically incorporated by reference herein.

[0023] The genomic loci of PCDH19 is 5001 -123630 of NG_021319.1 (RefSeqGene Number). Amino acid sequences of PCDH19 are publicly available. See, e.g., GenBank Accession Nos. NP_001 171809.1 , NP_001098713.1 , and NP_065817.2. An exemplary amino acid sequence of PCDH19 is: MESLLLPVLLLLAILWTQAAALINLKYSVEEEQRAGTVIANVAKDAREAGFALDPRQASAFRV VSNSAPHLVDINPSSGLLVTKQKIDRDLLCRQSPKCIISLEVMSSSMEICVIKVEIKDLNDNAP SFPAAQIELEISEAASPGTRIPLDSAYDPDSGSFGVQTYELTPNELFGLEIKTRGDGSRFAEL VVEKSLDRETQSHYSFRITALDGGDPPRLGTVGLSIKVTDSNDNNPVFSESTYAVSVPENSP PNTPVIRLNASDPDEGTNGQVVYSFYGYVNDRTRELFQIDPHSGLVTVTGALDYEEGHVYE LDVQAKDLGPNSIPAHCKVTVSVLDTNDNPPVINLLSVNSELVEVSESAPPGYVIALVRVSD RDSGLNGRVQCRLLGNVPFRLQEYESFSTILVDGRLDREQHDQYNLTIQARDGGVPMLQS AKSFTVLITDENDNHPHFSKPYYQVIVQENNTPGAYLLSVSARDPDLGLNGSVSYQIVPSQV RDMPVFTYVSINPNSGDIYALRSFNHEQTKAFEFKVLAKDGGLPSLQSNATVRVIILDVNDNT PVITAPPLINGTAEVYIPRNSGIGYLVTVVKAEDYDEGENGRVTYDMTEGDRGFFEIDQVNG EVRTTRTFGESSKSSYELIVVAHDHGKTSLSASALVLIYLSPALDAQESMGSVNLSLIFIIALG SIAGILFVTMIFVAIKCKRDNKEIRTYNCSNCLTITCLLGCFIKGQNSKCLHCISVSPISEEQDK KTEEKVSLRGKRIAEYSYGHQKKSSKKKKISKNDIRLVPRDVEETDKMNVVSCSSLTSSLNY FDYHQQTLPLGCRRSESTFLNVENQNTRNTSANHIYHHSFNSQGPQQPDLIINGVPLPETE NYSFDSNYVNSRAHLIKSSSTFKDLEGNSLKDSGHEESDQTDSEHDVQRSLYCDTAVNDVL NTSVTSMGSQMPDHDQNEGFHCREECRILGHSDRCWMPRNPMPIRSKSPEHVRNIIALSIE ATAADVEAYDDCGPTKRTFATFGKDVSDHPAEERPTLKGKRTVDVTICSPKVNSVIREAGN GCEAISPVTSPLHLKSSLPTKPSVSYTIALAPPARDLEQYVNNVNNGPTRPSEAEPRGADSE KVMHEVSPILKEGRNKESPGVKRLKDIVL (SEQ ID NO: 28)

[0024] mRNA sequences of PCDH19 are publicly available. See, e.g., GenBank Accession Nos. NM_001184880.2, NM_001105243.2, and NM_020766.3. An exemplary mRNA sequence of PCDH19 is: ATGGAGTCGCTCCTGCTGCCGGTGCTGCTGCTGCTGGCCATACTGTGGACGCAGGCT GCCGCCCTCATTAATCTCAAGTACTCGGTAGAAGAGGAGCAGCGCGCCGGGACGGTG ATTGCCAACGTGGCCAAAGACGCGCGAGAGGCGGGCTTCGCGCTGGACCCCCGGCA GGCTTCAGCCTTTCGCGTGGTGTCCAACTCGGCTCCACACCTAGTGGACATCAATCCC AGCTCTGGCCTGCTGGTCACCAAGCAGAAGATTGACCGTGATCTGCTGTGCCGCCAGA GCCCCAAGTGCATCATCTCGCTCGAGGTCATGTCCAGCTCAATGGAAATCTGCGTGAT AAAGGTGGAGATCAAGGACCTGAACGACAATGCGCCCAGTTTCCCGGCAGCACAGATC GAGCTGGAGATCTCGGAGGCAGCCAGCCCTGGCACGCGCATCCCGCTGGACAGCGCT TACGATCCAGACTCAGGAAGCTTTGGCGTGCAGACTTACGAGCTCACGCCCAACGAGC TGTTCGGCCTGGAGATCAAGACGCGCGGCGACGGCTCCCGCTTTGCCGAACTCGTGG TGGAAAAGAGCCTGGACCGCGAGACGCAGTCGCACTACAGCTTCCGAATCACTGCGCT AGACGGTGGCGACCCGCCGCGCCTGGGCACCGTTGGCCTTAGTATCAAGGTGACCGA CTCCAATGACAACAACCCGGTGTTTAGCGAGTCCACCTACGCGGTGAGCGTGCCAGAA AACTCGCCTCCCAACACACCCGTCATCCGCCTCAACGCCAGCGATCCAGACGAGGGCA CCAACGGCCAGGTGGTCTACTCCTTCTATGGCTACGTCAACGACCGCACGCGCGAGCT CTTTCAGATCGACCCGCACAGTGGCCTGGTCACTGTCACTGGCGCTTTAGACTACGAA GAGGGGCACGTGTACGAACTGGACGTGCAGGCTAAGGACTTGGGGCCCAATTCCATC CCGGCACACTGCAAGGTCACCGTCAGCGTGCTGGACACCAATGACAATCCGCCGGTC ATCAACCTGCTGTCAGTCAACAGTGAGCTTGTGGAGGTCAGCGAGAGCGCCCCCCCG

GGCTACGTGATCGCCTTGGTGCGGGTGTCTGATCGCGACTCAGGCCTCAATGGACGT

GTGCAGTGCCGTTTGCTGGGCAATGTGCCCTTTCGACTGCAGGAATATGAGAGCTTCT

CCACTATTCTGGTGGACGGACGGCTGGACCGCGAGCAGCACGACCAATACAACCTCAC

AATTCAGGCACGCGACGGCGGCGTGCCCATGCTGCAGAGTGCCAAGTCCTTTACCGT

GCTCATCACTGACGAAAATGACAACCACCCGCACTTTTCCAAGCCCTACTACCAGGTCA

TTGTGCAGGAGAACAACACGCCTGGCGCCTATCTGCTCTCTGTGTCTGCTCGCGACCC

CGACCTGGGTCTCAACGGCAGTGTCTCCTACCAGATCGTGCCGTCGCAGGTGCGGGA

CATGCCTGTCTTCACCTATGTCTCCATCAATCCCAACTCAGGCGACATCTACGCGCTGC

GATCCTTTAACCACGAGCAGACCAAGGCGTTCGAATTCAAGGTGCTGGCCAAGGACGG

CGGCCTTCCCTCACTGCAAAGCAACGCTACGGTGCGGGTCATCATCCTCGACGTCAAC

GACAACACCCCGGTCATCACAGCCCCACCTCTGATTAACGGCACTGCCGAGGTCTACA

TACCCCGCAACTCTGGCATAGGCTACCTGGTGACTGTTGTCAAGGCAGAAGACTACGA

TGAGGGCGAAAATGGCCGAGTCACCTACGACATGACCGAGGGCGACCGCGGCTTCTT

TGAAATAGACCAGGTCAATGGCGAAGTCAGAACCACCCGCACCTTCGGGGAGAGCTCC

AAGTCCTCCTATGAGCTTATCGTGGTGGCTCACGACCACGGCAAGACATCTCTCTCTGC

CTCTGCTCTCGTCCTAATCTACTTGTCCCCTGCTCTCGATGCCCAAGAGTCAATGGGCT

CTGTGAACTTGTCCTTGATTTTCATTATTGCCCTGGGCTCCATTGCGGGCATCCTCTTTG

TAACTATGATCTTCGTGGCAATCAAGTGCAAGCGAGACAACAAAGAGATCCGGACCTAC

AACTGCAGTAATTGTTTAACCATCACTTGTCTCCTCGGCTGTTTTATAAAAGGACAAAAC

AGCAAGTGTCTGCATTGCATCTCGGTTTCTCCCATTAGCGAGGAGCAAGACAAAAAGAC

AGAGGAGAAAGTGAGCCTAAGGGGAAAGAGAATTGCTGAGTACTCCTATGGGCATCAA

AAGAAATCAAGCAAGAAGAAAAAAATCAGTAAGAATGACATCCGCCTGGTACCCCGGG

ATGTGGAGGAGACAGACAAGATGAACGTTGTCAGTTGCTCTTCCCTGACCTCCTCCCTC

AACTATTTTGACTACCACCAGCAGACGCTGCCCCTGGGCTGCCGCCGCTCTGAGAGCA

CTTTCCTGAATGTGGAGAACCAGAATACCCGCAACACCAGTGCTAACCACATCTACCAT

CACTCTTTCAACAGCCAGGGGCCCCAGCAGCCTGACCTGATTATCAACGGTGTGCCTC

TGCCTGAGACTGAAAACTATTCTTTTGACTCCAACTACGTGAATAGCCGAGCCCATTTAA

TCAAGAGCAGCTCCACCTTCAAGGACTTAGAGGGCAACAGCCTGAAGGATAGTGGACA

TGAGGAGAGTGACCAAACTGACAGTGAGCATGATGTCCAGCGGAGCCTGTATTGTGAT

ACTGCTGTCAACGATGTGCTGAACACCAGTGTGACCTCCATGGGATCTCAGATGCCTG

ATCATGATCAGAATGAAGGATTTCATTGCCGGGAAGAATGCCGGATTCTTGGCCACTCT

GACAGGTGCTGGATGCCCCGGAACCCCATGCCCATCCGTTCCAAGTCCCCTGAGCATG

TGAGGAACATCATCGCGCTGTCTATTGAAGCTACTGCTGCTGATGTCGAGGCTTATGAC

GACTGCGGCCCCACCAAACGGACTTTCGCAACCTTTGGGAAAGATGTCAGCGACCACC

CGGCTGAGGAGAGGCCTACCCTGAAAGGCAAGAGGACTGTCGATGTGACCATCTGCA

GCCCCAAGGTCAACAGCGTTATCCGGGAGGCAGGCAATGGCTGTGAGGCGATTAGCC CTGTCACCTCCCCCCTCCACCTCAAGAGCTCTCTGCCCACCAAGCCTTCCGTGTCTTAC ACCATTGCCCTGGCTCCCCCAGCCCGTGATCTGGAGCAGTATGTCAACAATGTCAACA ATGGCCCTACTCGTCCCTCTGAAGCTGAGCCCCGTGGAGCTGATAGCGAGAAAGTCAT GCATGAGGTCAGCCCCATTCTGAAGGAAGGTCGCAACAAAGAGTCCCCTGGTGTGAAG CGTCTGAAGGATATCGTTCTCTA (SEQ ID NO: 29).

[0025] The terms "treatment", "treating", "treat" and the like are used herein to generally refer to obtaining a desired pharmacologic and/or physiologic effect. The effect may be prophylactic in terms of completely or partially preventing a disease or symptom thereof and/or may be therapeutic in terms of a partial or complete stabilization or cure for a disease and/or adverse effect attributable to the disease. "Treatment" as used herein covers any treatment of a disease in a mammal, particularly a human, and includes: (a) preventing the disease or symptom from occurring in a subject which may be predisposed to the disease or symptom but has not yet been diagnosed as having it; (b) inhibiting the disease symptom, i.e. , arresting its development; or (c) relieving the disease symptom, i.e., causing regression of the disease or symptom.

[0026] The terms "individual," "subject," "host," and "patient," are used interchangeably herein and refer to any mammalian subject for whom diagnosis, treatment, or therapy is desired, particularly humans.

DETAILED DESCRIPTION

[0027] Before the present compositions and methods are described, it is to be understood that this invention is not limited to particular compositions and methods described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.

[0028] Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limits of that range is also specifically disclosed. Each smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in that stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range, and each range where either, neither or both limits are included in the smaller ranges is also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the invention.

[0029] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, some potential and preferred methods and materials are now described. All publications mentioned herein are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications are cited. It is understood that the present disclosure supersedes any disclosure of an incorporated publication to the extent there is a contradiction.

[0030] It must be noted that as used herein and in the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a reprogramming factor polypeptide” includes a plurality of such polypeptides, and reference to "the induced pluripotent stem cells" includes reference to one or more induced pluripotent stem cells and equivalents thereof known to those skilled in the art, and so forth.

[0031] The publications discussed herein are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided may be different from the actual publication dates which may need to be independently confirmed.

METHODS FOR TREATING AN INDIVIDUAL HAVING PCDH19-RELATED ENCEPHALOPATHY

[0032] As summarized above, methods are provided for treating an individual having PCDH19-related disorder, the method containing administering an effective dose of an agent to the individual, wherein the agent modulates the expression of PCHD19; thereby modulating the expression of a PCDH19 protein.

[0033] The PCDH19-related condition may be any condition that is caused by a mutation in one allele of a PCDH19 gene that results in a loss of function, gain of function, or a reduction of function of the PCDH19 gene product. Mutations in the PCDH19 gene have been described in the art by, for example, Kolc et al. (Mol Psychiatry. 2019 Feb;24(2):241 -251 ). In some embodiments, the PCDH19-related condition is PCDH19-related encephalopathy. In some embodiments, PCDH19-related encephalopathy is PCDH19-related epilepsy. In some embodiments, PCDH19-related encephalopathy is PCDH19-related autism spectrum disorder. In some embodiments, PCDH19-related encephalopathy is PCDH19-related autism spectrum disorder and is PCDH19-related epilepsy.

[0034] The individuals that receive benefit from the methods disclosed herein are any individual that has a PCDH19-related condition. In some embodiments, the individual has mosaic expression of a functioning PCDH19 gene product. In some embodiments, the individual is female. In other embodiments, the individual is a mosaic male. [0035] Prior to the administration of the agent, the individual may be screened to determine if the individual would receive benefit from the treatments disclosed herein. Individuals that may receive benefit are individuals that have a mutation in one allele of a PCDH19 gene that results in a loss of function, gain in function, or a reduction of function of the PCDH19 gene product. Notable mutations include, without limitation, mutations in the PCDH19 gene that result in a Leu81 Arg amino acid substitution in the PCDH19 gene product, a Asn232Ser amino acid substitution in the PCDH19 gene product, a Asn340Ser amino acid substitution in the PCDH19 gene product, a Tyr366Leu, etc. Additional mutations that are known as pathogenic variants may be found in Table 1 . Pathogenic variants of PCDH19 are known in the art and have been described in, for example, Depienne et al. (Hum Mutat. 2012 Apr;33(4):627-34) which is specifically incorporated by reference herein. The screening of the individuals generally involves genetic testing of the individual. In some embodiments, the genetic testing is genotyping. In some embodiments, the genetic testing is a restriction fragment length polymorphism (RFLP) assay.

Table 1. Pathogenic Variants of PCDH19

[0036] The agents of the present disclosure are administered to an individual having the PCDH19-related condition. The agents may be administered using any method deemed useful for the treatment of the PCDH19-related condition. In some embodiments, the agent is administered systemically. In some embodiments, the systemic administration is through subcutaneous, intravenous, intracisternal magna, or intrathecal administration. In some embodiments, the agent is administered locally. In some embodiments, the local administration is intracerebroventricular or intraparenchymal administration.

[0037] The agent may be any agent that modulates the expression of a PCDH19 gene product. Agents of the present disclosure may be nucleic acids. When the agent is a nucleic acid, the nucleic acid can be any nucleic acid that modulates the expression of a PCDH19 gene product. Non-limiting examples of nucleic acids of the present disclosure include, without limitation, an antisense oligonucleotide, a double-stranded silencing RNA (siRNA), etc.

[0038] When the agent is a nucleic acid, the nucleic acid may have a modification. Such modifications may impart useful properties, e.g., increase the biological stability of the nucleic acid (e.g., nuclease resistance), enhance target binding, increase tissue uptake and/or increase the physical stability of the duplex formed between the nucleic acid and target nucleic acids, etc.

[0039] In certain embodiments, the nucleic acid may induce a steric block of a target sequence, and in such a way that it does not induce target cleavage via RNase H recruitment. For example, the nucleic acid may comprise a chemistry which does not support RNase H cleavage (e.g., does not generate consecutive runs of DNA or DNA-like bases). For example, the nucleic acid may comprise a “mixmer” pattern in which the nucleic acid may comprise two or more different nucleic acid chemistries but runs of more than 2 or 3 DNA or DNA-like bases (which would support RNase H-mediated cleavage) are avoided.

[0040] In certain embodiments, the nucleic acid of the present disclosure may contain DNA, RNA, and/or nucleotide analogues. The nucleotide analogues may be peptide nucleic acid (PNA), FANA, DANA, locked nucleic acid (LNA), and other branched nucleic acids (ENA, cEt), 7-deaza-dG, phosphorodiamidate morpholino oligomer (PMO), and/or tricyclo DNA.

[0041] According to some embodiments, the nucleic acid contains an abasic site, i.e., the absence of a purine (adenine and guanine) or a pyrimidine (thymine, uracil, and cytosine) nucleobase.

[0042] In certain embodiments, the nucleic acid contains a 3' to 5' phosphodiester (PO) linkage as naturally found in DNA or RNA. The nucleic acid may comprise a modified internucleoside linkage, e.g., a phosphotriester linkage, a phosphorothioate (PS) linkage, a boranophosphate linkage, a phosphorodiamidate linkage, a phosphoamidate linkage, and/or a thiophosphoramidate linkage. The modified internucleoside linkage may be other modifications known in the art. The modified internucleoside linkage may be present in all or a portion of the nucleic acid.

[0043] According to some embodiments, the nucleic acid contains one or more asymmetric centers and thus give rise to enantiomers, diasteromers, and other stereoisomeric configurations, e.g., R, S. For example, stereochemistry may be constrained at one or more modified internucleoside linkages. For example, the oligonucleotide may comprise repeated left-left-right (or SSR) chiral PS centers.

[0044] In some instances, the nucleic acid contains a sugar moiety as found in naturally occurring RNA (e.g., a ribofuranosyl) or a sugar moiety as found in naturally occurring DNA (e.g., a deoxyribofuranosyl). The nucleic acid may comprise a modified sugar moiety, i.e. a substituted sugar moiety or a sugar surrogate. Substituted sugar moieties include furanosyls comprising substituents at the 2'-position, the 3'-position, the 5 '-position and/or the 4'-position. A substituted sugar moiety may be a bicyclic sugar moiety (BNA). Sugar surrogates include morpholino, cyclohexeynl and cyclohexitol. The modified sugar moiety may be present in all or a portion of the nucleic acid.

[0045] The modified sugar moiety may comprise a 2'-O-methyl, 2'-O-methoxyethyl (2'-O- MOE), 2'-O-aminopropyl, 2'-deoxy, 2'-O- propyl (2'-O-AP), 2'-O-dimethylaminoethyl (2'0- DMAOE), 2'-0-dimethylaminopropyl (2'-O-DMAP), 2'-0-dimethylaminoethyloxyethyl (2'0- DMAEOE), or 2'0-N-methylacetoamido (2'0-NMA) modification or a locked or bridged ribose conformation (e.g., LNA, cEt, or ENA). The modified sugar moiety may comprise other modifications known in the art. The modified sugar moiety may be present in all or a portion of the nucleic acid.

[0046] According to some embodiments, the nucleic acid contains a terminal modification at its 5' and/or 3' end, such as a vinyl phosphonate, and/or inverted terminal bases. The terminal modification may be on the 5’ end, the 3’ end, or the 5’ and the 3’ end.

[0047] In certain embodiments, the nucleic acid contains a nucleobase as found in naturally occurring RNA and DNA (i.e. adenine (A), thymine (T), uracil (U), guanine (G), cytosine (C), inosine (I), and 5-methylcytosine). The nucleic acid may comprise a modified nucleobase, e.g. 5-hyrdoxymethylcytosine, 5-formylcytosine, and 5-carboxycytosine. The inclusion of 5'methylcytosine may enhance base pairing by modifying the hydrophobic nature of the nucleic acid.

[0048] In some instances, the nucleic acid contains a single type of nucleic acid chemistry (e.g., full PS, full -MOE, full PS -MOE, or full PMO) or combinations of different nucleic acid chemistries in all or a portion of the nucleic acid.

[0049] For example, each of the sugar moieties in the nucleic acid may contain a 2'-O- methoxyethyl (2'MOE; also known as 2’-O-methoxyethylribose) modification and each of the internucleoside linkages may be a phosphorothioate (i.e. a fully PS-MOE oligonucleotide). PS modifications are known to result in resistance to a broad spectrum of nucleases and increase protein binding, which also improves tissue uptake. 2'MOE modifications are known to enable enhanced binding affinity to the target mRNA with minimal toxicity and reduce plasma protein binding.

[0050] According to some embodiments, the nucleic acid contains a combination of PO and PS internucleoside linkages. This may facilitate fine tuning of the pharmacokinetics of the nucleic acid.

[0051] The nucleic acid may be modified with nucleotide analogues, modified sugar moieties, terminal modifications, internucleoside linkages, or any combination thereof. When a nucleic acid is modified, every nucleotide within the nucleic acid may be modified or a specific proportion of nucleotides may be modified. For instance, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100% of the nucleotides may be modified. In some embodiments, the nucleotides are modified with a mixture of the modifications described above. In some embodiments, the nucleotides are modified with one type of modification described above. In some embodiments, a portion or all of the nucleotides are modified with 2’-O- methoxyethylribose modifications. In some embodiments, a portion or all of the nucleotides are modified with phosphorothioate modifications. When all of the nucleotides are modified with phosphorothioate modifications it may be referred to as a phosphorothioate backbone. In some embodiments, a portion or all of the nucleotides are modified with 5-methylcytosine modifications. In some embodiments, a portion of the nucleotides are modified with 7-deaza- dG modifications. In some embodiments, a portion or all of the nucleotides are modified with locked nucleic acids modifications.

[0052] In some embodiments, a portion of the 5’ and 3’ terminal nucleotides may be modified while the central portion between the 5’ and 3’ terminal nucleotides are unmodified. For instance, one or more, two or more, three or more, four or more, five or more, six or more, seven or more, and eight or more nucleotides on each of the 5’ and 3’ ends may be modified. In some embodiments, two or more nucleotides on each of the 5’ and 3’ ends are modified. In some embodiments, three or more nucleotides on each of the 5’ and 3’ ends are modified. In some embodiments, four or more nucleotides on each of the 5’ and 3' ends are modified. In some embodiments, five or more nucleotides on each of the 5’ and 3’ ends are modified. In some embodiments, six or more nucleotides on each of the 5’ and 3’ ends are modified. In some embodiments, seven or more nucleotides on each of the 5’ and 3’ ends are modified. In some embodiments, eight or more nucleotides on each of the 5’ and 3’ ends are modified. The nucleotides on each the 5’ and 3’ ends have modification such as any of the those disclosed above including, without limitation, peptide nucleic acid (PNA), FANA, DANA, locked nucleic acid (LNA), and other branched nucleic acids (ENA, cEt), 7-deaza-dG, phosphorodiamidate morpholino oligomer (PMO), and/or tricyclo DNA, a phosphotriester linkage, a phosphorothioate (PS) linkage, a boranophosphate linkage, a phosphorodiamidate linkage, a phosphoamidate linkage, and/or a thiopho sphoramidate linkage, a 2'-O-methyl, 2'-O- methoxyethyl (2'-O-MOE), 2'-O-aminopropyl, 2'-deoxy, 2'-O- propyl (2'-O-AP), 2'-O- dimethylaminoethyl (2'O-DMAOE), 2'-O-dimethylaminopropyl (2'-O-DMAP), 2'-O- dimethylaminoethyloxyethyl (2'O-DMAEOE), or 2'O-N-methylacetoamido (2'0-NMA) modification, a 2'-O-methyl, 2'-0-methoxyethyl (2'-O-MOE), 2'-0-aminopropyl, 2'-deoxy, 2'-O- propyl (2'-O-AP), 2'-0-dimethylaminoethyl (2'O-DMAOE), 2'-0-dimethylaminopropyl (2'-O- DMAP), 2'-0-dimethylaminoethyloxyethyl (2'O-DMAEOE), 2'O-N-methylacetoamido (2'0- NMA) modification, or any combination thereof. In some embodiments, all or a portion of the 5’ and 3’ terminal nucleotides contain a combination of modifications. In some embodiments, the combination of modifications is phosphorothioate linkages and 2’-O-methoxyethylriboses. In some embodiments, all nucleotides of the nucleic acid are modified with phosphorothioate linkages. When all nucleotides of the nucleic acid are modified with phosphorothioate linkages, the nucleic acid has a phosphorothioate backbone.

[0053] In certain embodiments, the nucleic acid is produced using chemical synthesis and/or enzymatic ligation reactions using procedures known in the art. Alternatively, the nucleic acid may be produced biologically using an expression vector into which the oligonucleotide is subcloned in an antisense orientation, e.g., RNA transcribed from the inserted oligonucleotide will be of an antisense orientation to the target nucleic acid of interest.

[0054] The length of the nucleic acids of the present disclosure may be any length that is beneficial to the activity or function of the nucleic acid. For instance, the nucleic acid may be 15 to 35 nucleotides in length. The nucleic acid may be any intervening length including, without limitation, 15, 16, 17, 18, 19, 20, 21 , 22, 23, 24, 25, 26, 27, 28, 29, 30, 31 , 32, 33, 34, or 35 nucleotides in length.

[0055] The nucleic acids of the present disclosure may have a particular nucleic acid sequence. Particular nucleic acid sequences that find use in the present disclosure may be any nucleic acid sequence that modulates the expression of a PCDH19 gene product. When an individual is being treated for the PCDH19-related condition, the nucleic acid sequences may contain AAATCGCCACTAGCAGTCAC (SEQ ID NO: 6; ASO.6),

CATTAATCCCAAACCATCAC (SEQ ID NO: 7; ASO.7), GATGGCAAACTGGTACTACT (SEQ ID NO: 9; ASO.9), GTATGCAGTATTCTTTTCGC (SEQ ID NO: 14; ASO.14), AGTGTCATTTTCCCTACGCA (SEQ ID NO: 15; ASO.15), and

AAGTGTCATTTTCCCTACGC (SEQ ID NO: 16; ASO.16).

[0056] In some embodiments, the nucleic acid contains AAATCGCCACTAGCAGTCAC (SEQ ID NO: 6; ASO.6). In some embodiments, the nucleic acid consists of AAATCGCCACTAGCAGTCAC (SEQ ID NO: 6; ASO.6). In some embodiments, the nucleic acid contains CATTAATCCCAAACCATCAC (SEQ ID NO: 7; ASO.7). In some embodiments, the nucleic acid consists of CATTAATCCCAAACCATCAC (SEQ ID NO: 7; ASO.7). In some embodiments, the nucleic acid contains GATGGCAAACTGGTACTACT (SEQ ID NO: 9; ASO.9). In some embodiments, the nucleic acid consists of GATGGCAAACTGGTACTACT (SEQ ID NO: 9; ASO.9). In some embodiments, the nucleic acid contains GTATGCAGTATTCTTTTCGC (SEQ ID NO:14; ASO.14). In some embodiments, the nucleic acid consists of GTATGCAGTATTCTTTTCGC (SEQ ID NO: 14; ASO.14). In some embodiments, the nucleic acid contains AGTGTCATTTTCCCTACGCA (SEQ ID NO:15; ASO.15). In some embodiments, the nucleic acid consists of AGTGTCATTTTCCCTACGCA (SEQ ID NO: 15; ASO.15). In some embodiments, the nucleic acid contains AAGTGTCATTTTCCCTACGC (SEQ ID N0:16; AS0.16). In some embodiments, the nucleic acid consists of AAGTGTCATTTTCCCTACGC (SEQ ID NO: 16; ASO.16).

[0057] When the expression of PCDH19 is decreased, the expression of PCDH19 may be decreased by a range of different amounts. For instance, the expression of the PCDH19 may be decreased by at least about 2 fold, 5 fold, 10 fold, 20 fold, 30 fold, 40 fold, 50 fold, 100 fold, 200 fold, 300 fold, 500 fold, 1000 fold, 10000 fold or more than 10000 fold relative to the level of expression of the PCDH19 prior to administration of the agent.

[0058] In some embodiments, the methods of the present disclosure include administering two or more agents. The two or more agents may be administered sequentially or simultaneously. The two or more agents may be the same type of agent or a different type of agent. In some embodiments, the two or more agents are nucleic acids. In some embodiments, the two or more nucleic acids target different parts of the PCDH19 gene product.

COMPOSITIONS

[0059] Also, compositions for practicing the methods are described in the present disclosure. In general, subject compositions may have an agent as described above in addition to a pharmaceutically acceptable excipient. In some embodiments, the subject compositions contain a second agent as described above.

[0060] The agent may be any agent that modulates the expression of a PCDH19 gene and its protein products. Agents of the present disclosure may be nucleic acids. When the agent is a nucleic acid, the nucleic acid can be any nucleic acid that modulates the expression of a PCDH19 gene product. Non-limiting examples of nucleic acids of the present disclosure include, without limitation, an antisense oligonucleotide, a double-stranded silencing RNA (siRNA), etc. When the agent is a nucleic acid, the nucleic acid may have a modification. Such modifications may impart useful properties, e.g. increase the biological stability of the nucleic acid (e.g., nuclease resistance), enhance target binding, increase tissue uptake, and/or increase the physical stability of the duplex formed between the nucleic acid and target nucleic acids, etc.

[0061] Modifications that find use in the present disclosure include, without limitation, peptide nucleic acid (PNA), FANA, DANA, locked nucleic acid (LNA), and other branched nucleic acids (ENA, cEt), 7-deaza-dG, phosphorodiamidate morpholino oligomer (PMO), and/or tricyclo DNA, a phosphotriester linkage, a phosphorothioate (PS) linkage, a boranophosphate linkage, a phosphorodiamidate linkage, a phosphoamidate linkage, and/or a thiopho sphoramidate linkage, a 2'-O-methyl, 2'-0-methoxyethyl (2'-O-MOE), 2'-0-aminopropyl, 2'-deoxy, 2'-O- propyl (2'-O-AP), 2'-0-dimethylaminoethyl (2'O-DMAOE), 2'-Q-dimethylaminopropyl (2'-O- DMAP), 2'-0-dimethylaminoethyloxyethyl (2'O-DMAEOE), or 2'O-N-methylacetoamido (2'0- NMA) modification, a 2'-O-methyl, 2'-O-methoxyethyl (2'-O-MOE), 2'-O-aminopropyl, 2'- deoxy, 2'-O- propyl (2'-O-AP), 2'-O-dimethylaminoethyl (2'O-DMAOE), 2'-O- dimethylaminopropyl (2'-O-DMAP), 2'-O-dimethylaminoethyloxyethyl (2'O-DMAEOE), 2'0-N- methylacetoamido (2'0-NMA) modification, any combination thereof, etc.

[0062] When a nucleic acid is modified, every nucleotide within the nucleic acid may be modified or a specific proportion of nucleotides may be modified. For instance, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100% of the nucleotides may be modified. In some embodiments, the nucleotides are modified with a mixture of the modifications described above. In some embodiments, the nucleotides are modified with one type of modification described above. In some embodiments, a portion or all of the nucleotides are modified with 2’-0-methoxyethylribose modifications. In some embodiments, a portion or all of the nucleotides are modified with phosphonothioate linkages. In some embodiments, a portion or all of the nucleotides are modified with 5-methylcytosine modifications. In some embodiments, a portion of the nucleotides are modified with 7-deaza-dG modifications. In some embodiments, a portion or all of the nucleotides are modified with locked nucleic acid modifications.

[0063] In some embodiments, a portion of the 5’ and 3’ terminal nucleotides may be modified while the central portion between the 5’ and 3’ terminal nucleotides are unmodified. For instance, one or more, two or more, three or more, four or more, five or more, six or more, seven or more, and eight or more nucleotides on each of the 5’ and 3’ ends may be modified. In some embodiments, a portion of the 5’ and 3’ terminal nucleotides contain a combination of modifications. In some embodiments, the combination of modifications is phosphorothioate linkages and 2'-O-methoxyethylriboses. In some embodiments, all nucleotides of the nucleic acid are modified with phosphorothioate linkages. When all nucleotides of the nucleic acid are modified with phosphorothioate linkages, the nucleic acid has a phosphorothioate backbone.

[0064] The length of the nucleic acids of the present disclosure may be any length that is beneficial to the activity or function of the nucleic acid. For instance, the nucleic acid may be 15 to 35 nucleotides in length. The nucleic acid may be any intervening length including, without limitation, 15, 16, 17, 18, 19, 20, 21 , 22, 23, 24, 25, 26, 27, 28, 29, 30, 31 , 32, 33, 34, or 35 nucleotides in length.

[0065] The nucleic acids of the present disclosure may contain a particular nucleic acid sequence. Particular nucleic acid sequences that find use in the present disclosure may be any nucleic acid sequence that modulates the expression of a PCDH19 gene product. When an individual is being treated the PCDH19-related condition the nucleic acid sequences may contain AAATCGCCACTAGCAGTCAC (SEQ ID NO: 6; ASO.6),

AAGTGTCATTTTCCCTACGC (SEQ ID NO: 16; ASO.16).

[0066] In some embodiments, the nucleic acid contains AAATCGCCACTAGCAGTCAC (SEQ ID NO: 6; ASO.6). In some embodiments, the nucleic acid consists of AAATCGCCACTAGCAGTCAC (SEQ ID NO: 6; ASO.6). In some embodiments, the nucleic acid contains CATTAATCCCAAACCATCAC (SEQ ID NO: 7; ASO.7). In some embodiments, the nucleic acid consists of CATTAATCCCAAACCATCAC (SEQ ID NO: 7; ASO.7). In some embodiments, the nucleic acid contains GATGGCAAACTGGTACTACT (SEQ ID NO: 9; ASO.9). In some embodiments, the nucleic acid consists of GATGGCAAACTGGTACTACT (SEQ ID NO: 9; ASO.9). In some embodiments, the nucleic acid contains GTATGCAGTATTCTTTTCGC (SEQ ID NO:14; ASO.14). In some embodiments, the nucleic acid consists of GTATGCAGTATTCTTTTCGC (SEQ ID NO: 14; ASO.14). In some embodiments, the nucleic acid contains AGTGTCATTTTCCCTACGCA (SEQ ID NO:15; ASO.15). In some embodiments, the nucleic acid consists of AGTGTCATTTTCCCTACGCA (SEQ ID NO: 15; ASO.15). In some embodiments, the nucleic acid contains AAGTGTCATTTTCCCTACGC (SEQ ID NO:16; ASO.16). In some embodiments, the nucleic acid consists of AAGTGTCATTTTCCCTACGC (SEQ ID NO: 16; ASO.16).

[0067] The agent can be incorporated into a variety of compositions for administration. More particularly, the agent can be formulated into compositions by combination with appropriate, pharmaceutically acceptable excipients or diluents, and may be formulated into preparations in solid, semi-solid, liquid, or gaseous forms, such as tablets, capsules, powders, granules, ointments, solutions, injections, inhalants, and aerosols.

[0068] Compositions of the agent for administration to an individual (e.g., suitable for human administration) are generally sterile and may further be free of detectable pyrogens or other contaminants contraindicated for administration to a patient according to a selected route of administration.

[0069] In pharmaceutical dosage forms, the agents can be administered in the form of their pharmaceutically acceptable salts, or they may also be used alone or in appropriate association, as well as in combination, with other pharmaceutically active compounds. The following methods and carriers/excipients are merely examples and are in no way limiting.

[0070] For oral preparations, the agents can be used alone or in combination with appropriate additives to make tablets, powders, granules, or capsules, for example, with conventional additives, such as lactose, mannitol, corn starch, or potato starch; with binders, such as crystalline cellulose, cellulose derivatives, acacia, corn starch or gelatins; with disintegrators, such as corn starch, potato starch or sodium carboxymethylcellulose; with lubricants, such as talc or magnesium stearate; and if desired, with diluents, buffering agents, moistening agents, preservatives and flavoring agents. [0071] The agents can be formulated for parenteral (e.g., intravenous, subcutaneous, intraarterial, intraosseous, intramuscular, intracerebral, intracerebroventricular, intrathecal, etc.) administration. In certain embodiments, the agents are formulated for injection by dissolving, suspending, or emulsifying the agents in an aqueous or non-aqueous solvent, such as vegetable or other similar oils, synthetic aliphatic acid glycerides, esters of higher aliphatic acids or propylene glycol; and if desired, with conventional additives such as solubilizers, isotonic agents, suspending agents, emulsifying agents, stabilizers and preservatives.

[0072] Compositions that include the agents may be prepared by mixing the agents having the desired degree of purity with optional physiologically acceptable carriers, excipients, stabilizers, surfactants, buffers, and/or tonicity agents. Acceptable carriers, excipients and/or stabilizers are nontoxic to recipients at the dosages and concentrations employed, and include buffers such as phosphate, citrate, and other organic acids; antioxidants including ascorbic acid, glutathione, cysteine, methionine and citric acid; preservatives (such as ethanol, benzyl alcohol, phenol, m-cresol, p-chlor-m-cresol, methyl or propyl parabens, benzalkonium chloride, or combinations thereof); amino acids such as arginine, glycine, ornithine, lysine, histidine, glutamic acid, aspartic acid, isoleucine, leucine, alanine, phenylalanine, tyrosine, tryptophan, methionine, serine, proline and combinations thereof; monosaccharides, disaccharides and other carbohydrates; low molecular weight (less than about 10 residues) polypeptides; proteins, such as gelatin or serum albumin; chelating agents such as EDTA; sugars such as trehalose, sucrose, lactose, glucose, mannose, maltose, galactose, fructose, sorbose, raffinose, glucosamine, N-methylglucosamine, galactosamine, and neuraminic acid; and/or non-ionic surfactants such as Tween, Brij Pluronics, Triton-X, or polyethylene glycol (PEG).

[0073] The composition may be in a liquid form, a lyophilized form or a liquid form reconstituted from a lyophilized form, wherein the lyophilized preparation is to be reconstituted with a sterile solution prior to administration. The standard procedure for reconstituting a lyophilized composition is to add back a volume of pure water (typically equivalent to the volume removed during lyophilization); however, solutions comprising antibacterial agents may be used for the production of compositions for parenteral administration.

[0074] An aqueous composition of the agents may be prepared in a pH-buffered solution, e.g., at pH ranging from about 4.0 to about 7.0, or from about 5.0 to about 6.0, or alternatively about 5.5. Examples of buffers that are suitable for a pH within this range include phosphate-, histidine-, citrate-, succinate-, acetate-buffers, and other organic acid buffers. The buffer concentration can be from about 1 mM to about 100 mM, or from about 5 mM to about 50 mM, depending, e.g., on the buffer and the desired tonicity of the composition.

[0075] A tonicity agent may be included to modulate the tonicity of the composition. Example tonicity agents include sodium chloride, potassium chloride, glycerin, and any component from the group of amino acids, sugars as well as combinations thereof. In some embodiments, the aqueous composition is isotonic, although hypertonic or hypotonic solutions may be suitable. The term "isotonic" denotes a solution having the same tonicity as some other solution with which it is compared, such as physiological salt solution or serum. Tonicity agents may be used in an amount of about 5 mM to about 350 mM, e.g., in an amount of 100 mM to 350 mM. [0076] A surfactant may also be added to the composition to reduce aggregation and/or minimize the formation of particulates in the composition and/or reduce adsorption. Example surfactants include polyoxyethylensorbitan fatty acid esters (Tween), polyoxyethylene alkyl ethers (Brij) , alkylphenylpolyoxyethylene ethers (Triton-X), polyoxyethylene-polyoxypropylene copolymer (Poloxamer, Pluronic), and sodium dodecyl sulfate (SDS). Examples of suitable polyoxyethylenesorbitan-fatty acid esters are polysorbate 20, (sold under the trademark Tween 20™) and polysorbate 80 (sold under the trademark Tween 80™). Examples of suitable polyethylene-polypropylene copolymers are those sold under the names Pluronic® F68 or Poloxamer 188™. Examples of suitable Polyoxyethylene alkyl ethers are those sold under the trademark Brij™. Example concentrations of surfactant may range from about 0.001% to about 1 % w/v.

[0077] A lyoprotectant may also be added in order to protect the agent against destabilizing conditions during a lyophilization process. For example, known lyoprotectants include sugars (including glucose and sucrose); polyols (including mannitol, sorbitol, and glycerol); and amino acids (including alanine, glycine, and glutamic acid). Lyoprotectants can be included, e.g., in an amount of about 10 mM to 500 nM.

[0078] In some embodiments, the composition includes the agent, and one or more of the above-identified components (e.g., a surfactant, a buffer, a stabilizer, a tonicity agent) and is essentially free of one or more preservatives, such as ethanol, benzyl alcohol, phenol, m- cresol, p-chlor-m-cresol, methyl or propyl parabens, benzalkonium chloride, and combinations thereof. In other embodiments, a preservative is included in the composition, e.g., at concentrations ranging from about 0.001 to about 2% (w/v).

[0079] The composition may be administered using any method deemed useful for the treatment of PCDH19-related encephalopathy. In some embodiments, the agent is administered systemically. In some embodiments, the systemic administration is through subcutaneous, intravenous, intracisternal magna, or intrathecal administration. In some embodiments, the agent is administered locally. In some embodiments, the local administration is intracerebroventricular or intraparenchymal administration.

[0080] Each of the active agents can be provided in a unit dose of from about 0.1 pg, 0.5 pg, 1 pg, 5 pg, 10 pg, 50 pg, 100 pg, 500 pg, 1 mg, 5 mg, 10 mg, 50, mg, 100 mg, 250 mg, 500 mg, 750 mg or more. KITS

[0081] Also, kits for practicing the methods described in the present disclosure. In general, subject kits may contain the compositions, e.g., as described above. For instance, the kit may contain one or more agents as described above in addition to a pharmaceutically acceptable excipient. In some embodiments, the kit contains two or more agents as described above in addition to a pharmaceutically acceptable excipient. The kit may also include reagents for screening an individual to determine if the individual would receive benefit from the treatments disclosed herein. The reagents may include buffers, enzymes, nucleic acids, proteins, chemicals, small molecules, etc., for genetic testing such as genotyping or RFLP assays.

[0082] A subject kit can include any combination of components for performing the methods of the present disclosure. The components of a subject kit can be present as a mixture or can be separate entities. In some cases, components are present as a lyophilized mixture. In some cases, the components are present as a liquid mixture. Components of a subject kit can be in the same or separate containers, in any combination.

[0083] The subject kits may further include (in certain embodiments) instructions for practicing the subject methods. These instructions may be present in the subject kits in a variety of forms, one or more of which may be present in the kit. One form in which these instructions may be present is as printed information on a suitable medium or substrate, e.g., a piece or pieces of paper on which the information is printed, in the packaging of the kit, in a package insert, and the like. Yet another form of these instructions is a computer readable medium, e.g., diskette, compact disk (CD), flash drive, and the like, on which the information has been recorded. Yet another form of these instructions that may be present is a website address which may be used via the internet to access the information at a remote site.

EXPERIMENTAL

Results

[0084] Screening identifies ASOs that can reduce PCHD19 expression in human cortical organoids. Human cortical organoids (hCOs) were generated from three human induced pluripotent stem (hiPS) cell lines. For the initial screen, dissociated cells from hCOs derived from two hiPS cells were plated in the wells of 24-well plates. Single addition of 5 pM ASO was applied to the wells for 3-7 days, after which the cells were collected for gene expression analysis in comparison to cells exposed to a control scramble ASO with same chemical modification. For this screen, a total number of 26 ASOs were used.

[0085] Next, ASOs that resulted in reduced PCDH19 gene expression were validated. These ASOs (ASO.1 -ASO.8) were added to the 3D hCOs generated from three hiPS cell lines. Same as the initial screen, a single addition of 5 pM ASO was applied to the hCOs for 3-7 days, during which culture media was changed. At the end of the ASO exposure, hCOs were collected for gene expression analysis using qPCR. Further, for ASO.6, ASO.7, ASO.9, ASO.14, ASO.15, ASO.16, and ASO.Scr, an RT-PCR was performed for the amplification of a ~1 .7kb in the PCDH19 mRNA using the same amount of input cDNA.

Table 2. ASOs used in this study

[0086] Notwithstanding the appended clauses, the disclosure set forth herein is also described by the following clauses:

1 . A method for treating an individual having a PCDH19-related condition or disorder, the method comprising: administering an effective dose of an agent to the individual, wherein the agent modulates the expression of a PCDH19 gene product.

2. The method of clause 1 , wherein the agent is a nucleic acid.

3. The method of clause 2, wherein the nucleic acid is an antisense oligonucleotide (ASO).

4. The method of clause 3, wherein the ASO comprises one or more 2’-O- methoxyethylribose modifications.

5. The method of clause 3 or 4, wherein the ASO comprises one or more 2’-O- methoxyethylribose modifications on the 3’ end and the 5’ end of the ASO.

6. The method of clause 5, wherein the ASO comprises two or more 2’-O- methoxyethylribose modifications on the 3’ end and the 5’ end of the ASO.

7. The method of clause 5 or 6, wherein the ASO comprises five or more 2’-O- methoxyethylribose modifications on the 3’ end and the 5’ end of the ASO.

8. The method of any of clauses 3-6, wherein the ASO comprises a phosphorothioate backbone.

9. The method of clause 2, wherein the nucleic acid is a double-stranded silencing RNA (siRNA).

10. The method of any of the preceding clauses, wherein the PCDH19-related condition is PCDH19-related encephalopathy. 1 1 . The method of clause 10, wherein the PCDH19-related encephalopathy is PCDH19-related epilepsy.

12. The method of clause 10, wherein the PCDH19-related encephalopathy is PCDH19-related autism spectrum disorder.

13. The method of any of the preceding clauses, wherein the individual has a mutation in one allele of a PCDH19 gene that results in a loss of function, gain of function or a reduction of function of the PCDH19 gene product.

14. The method of any of the preceding clauses, wherein the individual has mosaic expression of a functioning PCDH19 gene product.

15. The method of any of the proceeding clauses, wherein the individual is female.

16. The method of any of clauses 2-15, wherein the agent comprises a sequence selected from the group consisting of AAATCGCCACTAGCAGTCAC (SEQ ID NO: 6; ASO.6), CATTAATCCCAAACCATCAC (SEQ ID NO: 7; ASO.7), GATGGCAAACTGGTACTACT (SEQ ID NO: 9; ASO.9), GTATGCAGTATTCTTTTCGC (SEQ ID NO: 14; ASO.14), AGTGTCATTTTCCCTACGCA (SEQ ID NO: 15; ASO.15), and

AAGTGTCATTTTCCCTACGC (SEQ ID NO: 16; ASO.16)

17. The method of any of clauses 2-16, wherein the agent comprises the sequence AAATCGCCACTAGCAGTCAC (SEQ ID NO: 6; ASO.6).

18. The method of any of clauses 2-16, wherein the agent comprises the sequence CATTAATCCCAAACCATCAC (SEQ ID NO: 7; ASO.7).

19. The method of any of clauses 2-16, wherein the agent comprises the sequence GATGGCAAACTGGTACTACT (SEQ ID NO: 9; ASO.9).

20. The method of any of clauses 2-16, wherein the agent comprises the sequence GTATGCAGTATTCTTTTCGC (SEQ ID NO: 14; ASO.14).

21 . The method of any of clauses 2-16, wherein the agent comprises the sequence AGTGTCATTTTCCCTACGCA (SEQ ID NO: 15; ASO15).

22. The method of any of clauses 2-16, wherein the agent comprises the sequence AAGTGTCATTTTCCCTACGC (SEQ ID NO: 16; ASO.16).

23. The method of any of the preceding clauses, wherein the treatment results in decreased expression of the PCDH19 gene product.

24. The method of any of the preceding clauses, further comprising genotyping the individual to determine if the individual has a mutation associated with the PCDH19-related condition prior to the administration.

25. The method of any of the preceding clauses, wherein two or more agents are administered to the individual.

26. The method of any of the preceding clauses, wherein the agent is administered locally. 27. The method of any of the preceding clauses, wherein the agent is administered systemically.

28. A composition, the composition comprising: the agent of any of the preceding clauses, and a pharmaceutically expectable excipient.

29. The composition of clause 19, further comprising a second agent.

30. The composition of clause 28 or 29, wherein the second agent is a nucleic acid.

31 . The composition of clause 30, wherein the nucleic acid is an antisense oligonucleotide (ASO).

32. The composition of clause 31 , wherein the ASO comprises one or more 2’-O- methoxyethylribose modifications in phosphorothioate backbone.

33. The composition of clause 32, wherein the nucleic acid is a double-stranded silencing RNA (siRNA).

34. The composition of any of clauses 29-33, wherein the second agent modulates the expression of PCDH19.

35. The composition of any of clauses 29-34, wherein the second agent comprises a sequence selected from the group of AAATCGCCACTAGCAGTCAC (SEQ ID NO: 6; ASO.6), CATTAATCCCAAACCATCAC (SEQ ID NO: 7; ASO.7), GATGGCAAACTGGTACTACT (SEQ ID NO: 9; ASO.9), GTATGCAGTATTCTTTTCGC (SEQ ID NO: 14; ASO.14), AGTGTCATTTTCCCTACGCA (SEQ ID NO: 15; ASO.15), and

AAGTGTCATTTTCCCTACGC (SEQ ID NO: 16; ASO.16)

36. The composition of any of clauses 29-35, wherein the second agent decreases expression of PCDH19.

37. A kit, the kit comprising: the composition of any of the preceding clauses.

[0087] In at least some of the previously described embodiments, one or more elements used in an embodiment can interchangeably be used in another embodiment unless such a replacement is not technically feasible. It will be appreciated by those skilled in the art that various other omissions, additions and modifications may be made to the methods and structures described above without departing from the scope of the claimed subject matter. All such modifications and changes are intended to fall within the scope of the subject matter, as defined by the appended claims.

[0088] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g, bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to embodiments containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “ a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “ a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.”

[0089] In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group.

[0090] As will be understood by one skilled in the art, for any and all purposes, such as in terms of providing a written description, all ranges disclosed herein also encompass any and all possible sub-ranges and combinations of sub-ranges thereof. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein can be readily broken down into a lower third, middle third and upper third, etc. As will also be understood by one skilled in the art all language such as “up to,” “at least,” “greater than,” “less than,” and the like include the number recited and refer to ranges which can be subsequently broken down into sub-ranges as discussed above. Finally, as will be understood by one skilled in the art, a range includes each individual member. Thus, for example, a group having 1 -3 articles refers to groups having 1 , 2, or 3 articles. Similarly, a group having 1-5 articles refers to groups having 1 , 2, 3, 4, or 5 articles, and so forth.

[0091] Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it is readily apparent to those of ordinary skill in the art in light of the teachings of this invention that certain changes and modifications may be made thereto without departing from the spirit or scope of the appended claims.

[0092] Accordingly, the preceding merely illustrates the principles of the invention. It will be appreciated that those skilled in the art will be able to devise various arrangements which, although not explicitly described or shown herein, embody the principles of the invention and are included within its spirit and scope. Furthermore, all examples and conditional language recited herein are principally intended to aid the reader in understanding the principles of the invention and the concepts contributed by the inventors to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents and equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims.

[0093] The scope of the present invention, therefore, is not intended to be limited to the exemplary embodiments shown and described herein. Rather, the scope and spirit of present invention is embodied by the appended claims. In the claims, 35 U.S.C. §1 12(f) or 35 U.S.C. §1 12(6) is expressly defined as being invoked for a limitation in the claim only when the exact phrase "means for" or the exact phrase "step for" is recited at the beginning of such limitation in the claim; if such exact phrase is not used in a limitation in the claim, then 35 U.S.C. § 1 12 (f) or 35 U.S.C. §1 12(6) is not invoked.

[0094] In at least some of the previously described embodiments, one or more elements used in an embodiment can interchangeably be used in another embodiment unless such a replacement is not technically feasible. It will be appreciated by those skilled in the art that various other omissions, additions and modifications may be made to the methods and structures described above without departing from the scope of the claimed subject matter. All such modifications and changes are intended to fall within the scope of the subject matter, as defined by the appended claims.

[0095] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to embodiments containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “ a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “ a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.” [0096] In addition, where features or aspects of the disclosure are described in terms of Markush groups, those skilled in the art will recognize that the disclosure is also thereby described in terms of any individual member or subgroup of members of the Markush group.

[0097] As will be understood by one skilled in the art, for any and all purposes, such as in terms of providing a written description, all ranges disclosed herein also encompass any and all possible sub-ranges and combinations of sub-ranges thereof. Any listed range can be easily recognized as sufficiently describing and enabling the same range being broken down into at least equal halves, thirds, quarters, fifths, tenths, etc. As a non-limiting example, each range discussed herein can be readily broken down into a lower third, middle third and upper third, etc. As will also be understood by one skilled in the art all language such as “up to,” “at least,” “greater than,” “less than,” and the like include the number recited and refer to ranges which can be subsequently broken down into sub-ranges as discussed above. Finally, as will be understood by one skilled in the art, a range includes each individual member. Thus, for example, a group having 1 -3 articles refers to groups having 1 , 2, or 3 articles. Similarly, a group having 1-5 articles refers to groups having 1 , 2, 3, 4, or 5 articles, and so forth.

[0098] Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it is readily apparent to those of ordinary skill in the art in light of the teachings of this invention that certain changes and modifications may be made thereto without departing from the spirit or scope of the appended claims.

[0099] Accordingly, the preceding merely illustrates the principles of the invention. It will be appreciated that those skilled in the art will be able to devise various arrangements which, although not explicitly described or shown herein, embody the principles of the invention and are included within its spirit and scope. Furthermore, all examples and conditional language recited herein are principally intended to aid the reader in understanding the principles of the invention and the concepts contributed by the inventors to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents and equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims.

[00100] The scope of the present invention, therefore, is not intended to be limited to the exemplary embodiments shown and described herein. Rather, the scope and spirit of present invention is embodied by the appended claims. In the claims, 35 U.S.C. §1 12(f) or 35 U.S.C. §112(6) is expressly defined as being invoked for a limitation in the claim only when the exact phrase "means for" or the exact phrase "step for" is recited at the beginning of such limitation in the claim; if such exact phrase is not used in a limitation in the claim, then 35 U.S.C. § 112 (f) or 35 U.S.C. §112(6) is not invoked.

Claims

THAT WHICH IS CLAIMED IS:

2. The method of claim 1 , wherein the agent is a nucleic acid.

3. The method of claim 2, wherein the nucleic acid is an antisense oligonucleotide (ASO).

4. The method of claim 3, wherein the ASO comprises one or more 2’-O- methoxyethylribose modifications.

5. The method of claim 3 or 4, wherein the ASO comprises one or more 2’-O- methoxyethylribose modifications on the 3’ end and the 5’ end of the ASO.

6. The method of claim 4 or 5, wherein the ASO comprises five or more 2’-O- methoxyethylribose modifications on the 3’ end and the 5’ end of the ASO.

7. The method of any of claims 3-6, wherein the ASO comprises a phosphorothioate backbone.

8. The method of claim 2, wherein the nucleic acid is a double-stranded silencing RNA (siRNA).

9. The method of any of the preceding claims, wherein the PCDH19-related condition is PCDH19-related encephalopathy.

10. The method of claim 9, wherein the PCDH19-related encephalopathy is PCDH19- related epilepsy or PCDH19-related autism spectrum disorder.

1 1 . The method of any of the preceding claims, wherein the individual has a mutation in one allele of a PCDH19 gene that results in a loss of function, gain of function, or a reduction of function of the PCDH19 gene product.

12. The method of any of the preceding claims, wherein the individual has mosaic expression of a functioning PCDH19 gene product.

13. The method of any of claims 2-12, wherein the agent comprises a sequence selected from the group consisting of AAATCGCCACTAGCAGTCAC (SEQ ID NO: 6; ASO.6), CATTAATCCCAAACCATCAC (SEQ ID NO: 7; ASO.7), GATGGCAAACTGGTACTACT (SEQ ID NO: 9; AS0.9), GTATGCAGTATTCTTTTCGC (SEQ ID NO: 14; ASO.14), AGTGTCATTTTCCCTACGCA (SEQ ID NO: 15; ASO.15), and

AAGTGTCATTTTCCCTACGC (SEQ ID NO: 16; ASO.16)

14. The method of any of the preceding claims, wherein the treatment results in decreased expression of the PCDH19 gene product.

15. The method of any of the preceding claims, further comprising genotyping the individual to determine if the individual has a mutation associated with the PCDH19-related condition prior to the administration.

16. The method of any of the preceding claims, wherein two or more agents are administered to the individual.

17. A composition, the composition comprising: the agent of any of the preceding claims, and a pharmaceutically expectable excipient.

18. The composition of claim 17, further comprising a second agent.

19. The composition of claim 17 or 18, wherein the second agent is an antisense oligonucleotide (ASO).

20. The composition of any of claims 17-19, wherein the second agent comprises a sequence selected from the group of AAATCGCCACTAGCAGTCAC (SEQ ID NO: 6; ASO.6), CATTAATCCCAAACCATCAC (SEQ ID NO: 7; ASO.7), GATGGCAAACTGGTACTACT (SEQ ID NO: 9; ASO.9), GTATGCAGTATTCTTTTCGC (SEQ ID NO: 14; ASO.14), AGTGTCATTTTCCCTACGCA (SEQ ID NO: 15; ASO.15), and

AAGTGTCATTTTCCCTACGC (SEQ ID NO: 16; ASO.16).