KCNH2 and familial long QT syndrome: LQT1 (KCNQ1 gene mutation), LQT2 (KCNH2), LQT3 (SCN5A) [56]; KCNQ1, KCNH2, and SCN5A genes, encoding the α subunit of the cardiac potassium channel Kv7.1; the α subunit of the cardiac hERG potassium channel and that of the cardiac sodium channel Nav1.5, respectively, involved in about 75% of LQTS patients [57]