MECP2 duplication syndrome: Recent advances in pathophysiology and therapeutic perspectives.

MECP2 duplication syndrome (MDS) is an X-linked neurodevelopmental disorder caused by duplication or extra copies of MECP2 gene. It primarily affects males and is characterized by intellectual disability, hypotonia, epilepsy, recurrent infections, and autistic features. Methyl-CpG binding protein 2 (MeCP2) encoded by MECP2 is a crucial epigenetic regulator of brain function. Expression levels are strictly regulated during brain development and maturation, and altered levels lead to severe neurodevelopmental disorders; excessive levels are associated with MDS, while insufficient levels cause Rett syndrome. This review provides a comprehensive overview of the recent advances in the pathophysiology and therapeutic perspectives of MDS, focusing on its pathophysiology, clinical features, disease models, and therapeutic strategies. Advances in studies using animal and patient-derived induced pluripotent stem cells (iPSCs)-derived neuronal models have provided insights into the molecular and cellular abnormalities associated with MDS and have facilitated therapeutic development. Among the emerging treatments, antisense oligonucleotide (ASO) therapy has gained significant attention as a promising approach for selectively suppressing MeCP2 overexpression. Preclinical studies using MDS mouse models and iPSCs-derived neurons have demonstrated that ASO treatment can partially restore neuronal abnormalities and clinical trials are currently underway.