KCNJ2 and Familial short QT syndrome: Moreover, gain-of-function KCNJ2 mutations have been implicated in human familial atrial fibrillation (Xia et al., 2005) and the SQT3 variant of the short QT syndrome (SQTS; Priori et al., 2005; Hattori et al., 2012; Deo et al., 2013; Ambrosini et al., 2014).