WNK4 and pseudohypoaldosteronism type 2: WNK4 is localized at TJs of distal nephrons and has been shown to selectively increase paracellular Cl− permeability and phosphorylate claudins in MDCK cells [18,25,26], and many studies have revealed that mutations of WNK4 are involved in the pathogenesis of PHAII [18,24,36,37].