Representative electrocardiograms of CALM-LQTS patients. (A) CALM3-D130G, male, 4 days, 12-lead electrocardiogram showing markedly prolonged QTc and 2:1 atrioventricular block. (B) CALM 1-D130G, female, 2 years, Holter recording showing markedly prolonged QTc and phases of T wave alternans. (C) Holter electrocardiogram showing the ventricular fibrillation onset in a CALM1-D130G, female, 9 months.