About 75% of the CMS cases are due to mutations in genes that encode different subunits of the acetylcholine receptor (CHRNA1, CHRNB1, CHRND, CHRNE) or proteins important to maintain the structure or function of the NMJ, such as MUSK, RAPSN or DOK7 [16, 17]. This evidence concerns the gene CHRND and congenital myasthenic syndrome.