KCNH2 and familial long QT syndrome: Indeed, comprehensive open reading frame analysis of these three canonical LQTS-causative genes—KCNQ1-encoded Kv7.1 channel subunit (LQT1), KCNH2-encoded Kv11.1 (LQT2), and SCN5A-encoded Nav1.5 (LQT3)—yields putative LQTS-associated mutations in 75% of clinically definite LQTS cases [29].