KCNJ2 and Andersen-Tawil syndrome: Compared to Nav1.5, LoF variants in Kv7.1 and Kv11.1 are clinically less complex, causing LQT1 and LQT2 (9) respectively, while LoF variants in Kir2.1 cause Anderson-Tawil Syndrome (ATS) and Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT)-phenocopy syndrome (66) (Figure 1D).