KCNH2 and familial long QT syndrome: They analyzed cardiac arrhythmia, respiratory control, and epilepsy genes, identifying four pathogenic and two candidate pathogenic variants of cardiac arrhythmia genes: a de novo SCN5A Ile397Val variant, a Gly924Ala and Arg744* nonsense variant in KCNH2, and a Tyr662* nonsense variant in KCNQ1. The variants in KCNQ1 and KCNH2 were previously reported in patients diagnosed with LQTS, and these three variants were absent in more than 60,000 population controls.