KCNJ2 and Andersen-Tawil syndrome: Andersen-Tawil syndrome (ATS; also referred to as LQT7) is a rare autosomal dominant channelopathy caused in ∼60% of cases by loss-of-function or dominant-negative mutations in KCNJ2, encoding the Kir2.1 inward-rectifier potassium channel, which plays a critical role in stabilizing the resting membrane potential of skeletal and cardiac muscle cells [4].