We investigated mutants from a diverse set of well-studied protein trafficking diseases including the nephrogenic diabetes insipidus mutations V206D and L292P in the arginine-vasopressin receptor 2 (AVPR2, also known as V2R) [24,25], the LQTS2 mutations G601S and F805C in the human ether-a-go-go-related gene (KCNH2, also known as hERG) [26,27], and finally the persistent hyperinsulinemic hypoglycemia of infancy (PHHI, also known as congenital hyperinsulinism) mutations A116P and V187D in the sulfonylurea receptor 1 (ABCC8, also known as SUR1) [10,28,29], a component of the KATP channel. Here, ABCC8 is linked to congenital isolated hyperinsulinism.