RYR2 and catecholaminergic polymorphic ventricular tachycardia 1: To date, more than ~160 mutations in RYR2, the gene encoding for the cardiac isoform of the RyR (RyR2), are linked to CPVT1, the dominant form of the syndrome, but it is clear that CPVT is an arrhythmogenic syndrome caused by intracellular Ca2+ mishandling, as mutations in cardiac isoform of the calsequestrin (CSQ2) [9] and triadin [10], two SR luminal proteins that regulate Ca2+ release through RyR2 channels, cause a recessive form of the disease (CPVT2 and CPVT3, respectively).