KCNJ8 and Cowden syndrome 1: KATP channels are hetero-octameric complexes, with ABCC9 (SUR2) and KCNJ8 (Kir6.1) prominently expressed in cardiomyocytes, vascular smooth muscle and vascular endothelial cells (Flagg et al., 2010), suggesting that cardiovascular features may predominate in CS (Armstrong et al., 2016).