[Bartter's syndromes]

Bartter syndromes are defined as a family of inherited recessive autosomal tubulopathies. They are characterized by hypochloremia, hypokalemia, metabolic alkalosis associated with potassium renal leakage and normal blood pressure despite increased plasma renin activity. Three forms of the disease are identified as followed: 1) Gitelman syndrome or hypocalciuria hypomagnesemia 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-Cl cotransporter located in the distal convoluted tubule. 2) Antenatal Bartter syndrome with hypercalciuria and nephrocalcinosis or hyperprostaglandin E syndrome is a severe form, often 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 inwardly-rectifying potassium channel (ROMK) [type II]. 3) the classical form or type III Bartter syndrome, often revealed by dehydration in the first year of life, is associated with hypomagnesemia in 20% of cases and normal or increased calciuria. This form is related to mutations of CLCNKB gene encoding for a chloride channel in Henle's loop. This classification, in part related to the demonstration of mutations in the genes encoding for tubular chloride or potassium channels, does not fit all cases, overlapping syndromes are frequent. Moreover some endocrinological (diabetes) and neurological (deafness) abnormalities are sometimes associated with Bartter syndromes. Both phenotypic and genetic approach must help to the diagnosis of these tubulopathies.