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. This evidence concerns the gene RYR2 and catecholaminergic polymorphic ventricular tachycardia.