RYR2 and catecholaminergic polymorphic ventricular tachycardia: Zhang X et al. established RYR2-CPVT-related mutation in hiPSC-CMs by CRISPR/Cas9 gene editing, and found that large sarcoplasmic reticulum Ca2+ leakage and smaller sarcoplasmic reticulum Ca2+ content were detected in cells carrying p.(Gln4201Arg) mutation (31).