RYR2 and catecholaminergic polymorphic ventricular tachycardia: In approximately 60% of cases, CPVT is caused by mutations in three genes encoding sarcoplasmic reticulum (SR) Ca2+ handling proteins, the cardiac ryanodine receptor (RyR2), calsequestrin 2 (Casq2) (Faggioni et al., 2012), or calmodulin (CaM) (Nyegaard et al., 2012; Crotti et al., 2013).