Bartter's syndromes

Bartter syndromes are defined as a family of inherited recessive autosomal tubulopathies. They are characterized by hypochloremia, hypokalemia.,metabo lic alkalosis associated with potassium renal leakage and normal blood pres sure despite increased plasma, renin activity. Three forms of the disease a re identified as followed: 1) Gitelman syndrome or hypocalciuria hypomagnes emia syndrome is a mild form often discovered in childhood or teenagers in reason of tetany. It is an homogeneous disorder related to mutations of the genes encoding the thiazide-sensitive Na-CI cotransporter located in the d istal convoluted tubule. 2) Antenatal Bartter syndrome with hypercalciuria and nephro calcinosis ol hyperprostaglandin E syndrome is a severe form, of ten revealed by hydramnios, prematurity and growth delay. It is related to mutations of two types of genes encoding for transporters of Henle's loop : the bumetanide-sensitive cotransporter Na-K-2Cl (NKCC2) [type I] or the in wardly-rectifying potassium channel (ROMK) [type II]. 3) the "classical" fo rm or type III Bartter syndrome, often revealed by dehydration in the first year of life, is associated with hypomagnesemia in 20 % of cases and norma l or increased calciuria. This form is related to mutations of CLCNKB gene encoding for a chloride channel in Henle's loop. This classification, in pa rt related to the demonstration of mutations in the genes encoding for tubu lar chloride or potassium channels, does not fit all cases, overlapping syn dromes are frequent. Moreover some endocrinological (diabetes) and neurolog ical (deafness) abnormalities are sometimes associated with Bartter syndrom es. Both phenotypic and genetic approach must help to the diagnosis of thes e tubulopathies.