The discovery of cardiac ion channel genes underpinning Long QT Syndrome (LQTS; MIM 192500) in the 1990s–KCNQ1 (KVLQT1) (Wang Q. et al., 1996), KCNH2 (KV11.1/hERG) (Curran et al., 1995), SCN5A (NaV1.5) (Wang et al., 1995)—were a major breakthrough in our understanding of congenital arrhythmia syndromes. The gene discussed is KCNQ1; the disease is Prolonged QT interval.