GNAS and renal hypomagnesemia 2: For example,Aqp1 is involved in water reabsorption at theapical and basolateral plasma membrane of the proximal tubule [36]; mutations in Fxyd2 have been associated with renal hypomagnesemia-2 [37]; Rab7, asa Rab member, could be implicated in the transport, docking, and fusion ofendocytotic vesicles [30], andfinally, Gnas codifies the alpha subunit ofheterotrimeric G proteins, which mediates the vasopressin receptor type 2signaling after the binding with vasopressin, and ultimately increases waterreabsorption in the collecting duct [36].