KCNQ1 and familial long QT syndrome: LQTS exists in more than 10 different subtypes, but research has mainly focused on LQTS1, LQTS2, and LQTS3, which result from a genetic mutation of the potassium voltage-gated channel subfamily Q member 1 (KCNQ1), subfamily H member 2 (KCNH2), and sodium voltage-gated channel α-subunit 5 (SCN5A), respectively (David et al., 2014).