Address for Correspondence: Dr. Rahul P. Bhamkar, Flat No. 9, Nest Building, Sector 1, Kalamboli, Navi Mumbai. India.
Email: brahul_11@sify.com

Abstract

Bartter's syndrome (BS) is an autosomal recessive disorder characterized by hypokalemic, hypochloremic metabolic alkalosis with normal or low blood pressure despite high plasma renin activity and serum aldosterone. It has been classified into different types based on its different phenotypic presentation and genetic etiology.

Introduction:

Bartter's syndrome (BS) is a group of inherited salt losing tubulopathies presenting as metabolic alkalosis with normotensive hyperreninemia and hyperaldosteronism. The inheritance pattern is autosomal recessive. Since Fredric Bartter and his colleagues first described these features in two children and a man in 1962, many advances have occurred in better understanding the genetics, pathophysiology, clinical features and management of the disease.(1)

Classification

Depending on the severity and age of presentation BS can be classified as

• Antenatal Bartter syndrome
 
• Classical Bartter's syndrome Antenatal BS is characterized by in utero or neonatal age of presentation, presence of nephrocalcinosis, higher urinary loss of sodium, potassium and chloride compared to that in classical BS

Based on pathophysiology and genetics, B.S. can be classified as (Table 1) (2):

• Antenatal BS type I, involving defect in NaK2Cl cotransporter in thick ascending limb (TAL) because of mutation in SLC12A1 gene on 15q15-21 chromosome.
 
• Antenatal BS type II, involving defect in ROMK (Renal Outer Medullary Potassium Channel) in TAL and collecting duct (CD) because of mutation in KCNJ1 gene on chromosome 11q24.
 
• Classic BS type III, involving defect in CIC-Kb channel in TAL and distal convoluted tubule (DCT) because of mutation in CLCNKB gene on chromosome 1p36.
 
• BS type IV, Bartter's syndrome with sensorineural deafness (BSND) variant occurs because of mutation in the BSND gene on chromosome 1p31 coding for protein "Barttin" which forms subunit of CICKb and CICKa channel located on basolateral membrane of TAL and inner ear epithelium.
 
• Gitelman's or hypomagnesemic variant involving defect in NCCT channels in distal tubule because of mutation in SLC12A3 gene on chromosome 16q13.
 
• Pseudo-Bartter's syndrome