KCNH2 and familial long QT syndrome: LQT2 is a major form of LQTS, which is caused by loss-of-function (LOF) mutations in the KCNH2 gene (a.k.a the human ether-a-go-go related gene or hERG) (Curran et al., 1995; Sanguinetti et al., 1996; Smith et al., 2016).