RYR2 and catecholaminergic polymorphic ventricular tachycardia: Mutations in RyR2 associated with CPVT usually cause increased SR Ca2+ leak that is exacerbated by β-adrenergic stimulation, but both gain- and loss-of-function mutations have been reported (Wehrens et al., 2003; Loaiza et al., 2013; Zhao et al., 2015; Landstrom et al., 2017; Uehara et al., 2017).