RYR2 and catecholaminergic polymorphic ventricular tachycardia: As yet, two main types of CPVT-associated RyR2 mutations have been identified; gain-of-function (Jiang et al., 2002, 2005) and loss-of-function (Jiang et al., 2007; Zhao et al., 2015) mutations purportedly increase and decrease channel sensitivity to luminal Ca2+, respectively.