KCNH2 and familial long QT syndrome: Three encoding ion channels genes have been identified as responsible for most of the LQTS cases: KCNQ1 (Kv7.1 channel) causing LQT1,4KCNH2 (hERG ‐ Kv11.1 channel) causing LQT25 and SCN5A (Nav1.5 channel) causing LQT3.6