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. Here, CALM1 is linked to catecholaminergic polymorphic ventricular tachycardia.