In humans, loss of function mutations in the gene KCNJ10 (encoding Kir4.1) are the cause of EAST/SESAME (epilepsy, ataxia, sensorineural deafness, and renal tubulopathy/seizures, sensorineural deafness, ataxia, mental retardation, and electrolyte imbalance) syndrome (Bockenhauer et al., 2009; Scholl et al., 2009), a complex disease characterized, among other manifestations, by hypokalemic metabolic alkalosis, hypomagnesemia, and hypocalciuria, a phenotype reminiscent of Gitelman syndrome. This evidence concerns the gene KCNJ10 and Hypomagnesemia.