Polyuria-polydipsic symptoms are frequently observed in patients with Bartter syndrome. Bartter syndrome is secondary to loss-of-function mutations in
three different genes. Mutations in the bumetanide-sensitive Na-K-2Cl cotransporter gene (NKCC2) cause Bartter syndrome type I.15 NKCC2 is expressed
exclusively in apical membranes of thick ascending limb cells. NKCC2 (A) is a large protein with a core molecular weight of about 120 kDa and its topology
includes a large hydrophobic central region that includes at least 12 membrane-spanning helices. Sugar residues are linked to an extracellular loop
between the seventh and eighth membrane-spanning segments, making this cotransporter a glycoprotein and increasing its apparent molecular weight on
western blotting to 150 to 165 kDa. Mutations in the gene that encodes the inwardly rectifying renal potassium channel ROMK (B) cause Bartter syndrome
Source: Nephrogenic Diabetes Insipidus, The Online Metabolic and Molecular Bases of Inherited Disease
type II.16, 17 Mutations in the gene that encodes the renal chloride channel CLCNKB (C) cause Bartter syndrome type III.18
Citation: Valle D, Beaudet AL, Vogelstein B, Kinzler KW, Antonarakis SE, Ballabio A, Gibson K, Mitchell G. The Online Metabolic and Molecular
Bases of Inherited Disease; 2014 Available at: http://mhmedical.com/ Accessed: July 31, 2017
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