In the case of CM, a groundbreaking study in 2013 by Shirley and colleagues discovered a hyperactive, somatic nonsynonymous single-nucleotide variant (c.548G>A; p.R183Q) in the gene (GNAQ) encoding guanine nucleotide–binding protein Q subunit α (Gαq) in affected tissue from 88% of syndromic (SWS) and 92% of nonsyndromic CMs. This evidence concerns the gene GNAQ and congenital myasthenic syndrome.