RYR2 and catecholaminergic polymorphic ventricular tachycardia 1: To examine the involvement of the β8–β9 loop in RyR2 pathophysiology, we investigated the R176Q mutation linked with arrhythmogenic right ventricular dysplasia type 2 (ARVD2)23 and catecholaminergic polymorphic ventricular tachycardia (CPVT).24