KCNJ2 and catecholaminergic polymorphic ventricular tachycardia: On the other hand, KCNJ2, encoding inward‐rectifier potassium current (IK1), has also been reported to be responsible for an atypical type of CPVT,(Tester et al., 2006) although KCNJ2 is typically responsible for Andersen–Tawil syndrome (ATS) characterized by (a) VAs with prominent U‐waves (≥0.2 mV) on baseline ECG, (b) periodic paralysis, and (c) dysmorphic features.