CS is caused by gain‐of‐function (GoF) pathogenic variants in ABCC9 and, less commonly, in KCNJ8, which encode the regulatory (SUR2) and pore‐forming (Kir6.1) subunits, respectively, of ATP‐sensitive potassium (KATP) channels(Brownstein et al., 2013; Cooper et al., 2014; Harakalova et al., 2012; McClenaghan et al., 2017; van Bon et al., 2012). This evidence concerns the gene ABCC9 and Cowden syndrome 1.