Pathogenic mutations in KCNQ1, KCNH2, and SCN5A cause long-QT syndrome types 1, 2, and 3 (LQT1, LQT2, and LQT3), respectively, and together account for 97% of patients with genetically confirmed LQTS [2]. The gene discussed is KCNQ1; the disease is familial long QT syndrome.