Heterozygous Intragenic Deletion in MEF2C Causes a Neurodevelopmental Disorder with Stereotypic Hand Movements

Heterozygous disease-causing variants in MEF2C cause neurodevelopmental disorder characterized by developmental delay, hypotonia, stereotypical hand movements, and impaired language (NEDHSIL, MIM# 613443). We report a proband with seizures, language delay, and repetitive hand movements. Through copy number analysis of exome sequencing data, we identified heterozygous intragenic deletion involving exon 2–6 of MEF2C , which was validated by quantitative polymerase chain reaction . We emphasize that MEF2C -related NEDHSIL should be considered as one of the clinical possibilities in individuals presenting with a neurodevelopmental disorder and stereotypic hand movements. We also reiterate the importance of copy number variant analysis from exome sequencing data as a valuable tool in identifying additional causative variants, particularly intragenic copy number variations, and thus increasing the overall diagnostic yield.