To date, mutations in thirteen genes have been identified as causing 13 types of LQTS (LQT1-13) (Schwartz et al., 2012) and are divided into three major groups: (1) mutations in genes encoding voltage-gated channels [KCNQ1 (LQT1), KCNH2 (LQT2), SCN5A (LQT3), KCNJ2 (LQT7), KCNJ5 (LQT13)], (2) mutations in genes encoding subunits regulating voltage-gated channel [KCNE1 (LQT5), KCNE2 (LQT6), SCN4B (LQT 10)], and (3) mutations in genes encoding channel interacting proteins [ANKB (LQT4), KCNE1 (LQT5), KCNE2 (LQT6), CAV3 (LQT9)]. The gene discussed is SCN5A; the disease is familial long QT syndrome.