Bartter syndrome is due to impaired function of the Na+-K+-2Cl– cotransporter (NKCC2) in the thick ascending limb (TAL) of the loop of Henle, whereas Gitelman syndrome is due to impaired function of the Na+-Cl– cotransporter (NCC) in the distal convoluted tubule (DCT) (3–6). This evidence concerns the gene SLC12A3 and Gitelman syndrome.