Electroclinical features of MEF2C haploinsufficiency-related epilepsy: a multicenter European study.

The MADS box transcription enhancer factor 2 polypeptide C encoded by MEF2C (MIM *600662) is an immediate downstream transcriptional target and effector of endothelin signaling in the neural crest [1]. MEF2C encompasses up to 11 coding exons spanning approximately 100 kb on chromosome 5q14.3 and displays a tissue-specific expression, which is higher in the brain, heart, and skeletal muscle [2]. MEF2C haploinsufficiency resulting from heterozygous loss-of-function single nucleotide variants (SNVs) and 5q14.3 deletions (5q14.3 deletion syndrome) is associated with autosomal dominant mental retardation syndrome-20 (MRD20, MIM #613443) [2].