Pathological decreases in IKs are generally mediated by congenital mutations in KCNQ1 (LQT1) or KCNE1 (LQT5), with loss-of-function mutations in KCNQ1 accounting for ~30–45% of all inherited LQT cases (Tester et al., 2005). The gene discussed is KCNQ1; the disease is long QT syndrome 1.