RYR2 and catecholaminergic polymorphic ventricular tachycardia: Parameters were also comparable to those previously recorded in CMs from CPVT1 iPSC lines generated by us from a patient carrying the E2311D heterozygous mutation in the cardiac ryanodine receptor gene (RyR2).9 Instead, when exposed to β-adrenergic stimulation by isoproterenol, HO-CMs displayed delayed afterdepolarizations (DADs) and, less frequently, triggered activity (TA) during the diastolic depolarization phase (Figure 3b) that represent hallmarks of CPVT-CMs.9, 10, 11, 12, 19 These phenomena were absent in both WT- and HE- CMs, used as controls (Supplementary Figures 4C,D).