RYR2 and catecholaminergic polymorphic ventricular tachycardia: Two genetic subtypes were identified to underlie CPVT: CPVT1, an autosomal dominant form accounting for ~65% of all genotyped CPVT cases, is associated with mutations in the gene encoding the cardiac ryanodine receptor (RYR2), the calcium-releasing channel at the sarcoplasmatic reticulum (SR).