Modeling antisense oligonucleotide therapy in MECP2 duplication syndrome human iPSC-derived neurons reveals gene expression programs responsive to MeCP2 levels.

Genomic copy-number variations (CNVs) that can cause neurodevelopmental disorders often encompass many genes, which complicates our understanding of how individual genes within a CNV contribute to pathology. MECP2 duplication syndrome (MDS or MRXSL in OMIM; OMIM#300260) is one such CNV disorder caused by duplications spanning methyl CpG-binding protein 2 (MECP2) and other genes on Xq28. Using an antisense oligonucleotide (ASO) to normalize MECP2 dosage is sufficient to rescue abnormal neurological phenotypes in mouse models overexpressing MECP2 alone, implicating the importance of increased MECP2 dosage within CNVs of Xq28.