KCNJ2 and Andersen-Tawil syndrome: The importance of Kir2.1 in contributing to native IK1 is demonstrated by the fact that loss-of-function KCNJ2 mutations have been implicated in Andersen-Tawil syndrome, which causes one form of long QT syndrome (long QT type 7) as well as extra-cardiac abnormalities (Tristani-Firouzi and Etheridge, 2010; Perez-Riera et al., 2021).