Mutations in the ion channels Kv7.1, hERG, CASQ2, and RyR2 account for over 70% of cases; however, genetic screening of patients has revealed an association between LQTS/CPVT and genetic variation in calmodulin (CaM).8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23. The gene discussed is CALM1; the disease is familial long QT syndrome.