A molecular update on Pseudohypoaldosteronism type II
Published online on October 09, 2013
Abstract
The DCT (distal convoluted tubule) is the site of micro-regulation of water reabsorption and ion handling in the kidneys, which is mainly under the control of aldosterone. Aldosterone binds to and activates mineralocorticoid receptors, which ultimately leads to increased sodium reabsorption in the distal part of the nephron. Impairment of mineralocorticoid signal transduction results in resistance to aldosterone and mineralocorticoids, and, therefore, causes disturbances in electrolyte balance. Pseudohypoaldosteronism type II (PHAII) or familial hyperkalemic hypertension (FHHt) is a rare, autosomal dominant syndrome characterized by hypertension, hyperkalemia, metabolic acidosis, elevated or low aldosterone levels, and decreased plasma renin activity. PHAII is caused by mutations in the WNK isoforms (with no lysine kinase), which regulate the Na-Cl and Na-K-Cl cotransporters (NCC and NKCC2, respectively) and renal outer medullary potassium (ROMK) channel in the DCT. This review focuses on new candidate genes such as KLHL3 and Cullin3, which are instrumental to unravel novel signal transductions pathways involving NCC, to better understand the cause of PHAII along with the molecular mechanisms governing the pathophysiology of PHAII and its clinical manifestations.