Mg active transport in the GI tract is regulated by TRPM cation channels 6 and 7 and they are up regulated by activation of colonic H+K+ATPase, and it is proposed that PPIs inhibition of colonic H+K+ATPase results in decreased TRPM activity, causing hypomagnesemia in some patients [319,320,322]. The gene discussed is ATP12A; the disease is familial primary hypomagnesemia.