Type IV Bartter syndrome: report of two new cases
Bartter syndrome with sensorineural deafness (type IV Bartter syndrome) is a subtype of this tubular disease, and is due to mutations in the BSND gene. Out of a population of 92 patients with Bartter syndrome, five suffered from mild to severe hypoacusia and were selected for mutational screening. A homozygous mutation in the BSND gene was found in two female patients. The first patient was found to have a substitution in intron 1 donor splice site at position +5 (c.420+5G>C), whereas the second patient has a homozygous 3G>A substitution leading to the loss of the start codon for the translation of the BSND mRNA. The clinical courses of these two patients were remarkable for severe polyhydramnios, massive renal salt and water wasting, severe neonatal hypotonia, poor growth and unresponsiveness to prostaglandin inhibitors. The diuretic responses to furosemide and to hydrochlorothiazide were tested under KCl supplementation in one patient. A lack of response to both drugs suggested that inhibition of NaCl reabsorption in type IV Bartter syndrome is not restricted to the thick ascending limb of Henle. In one patient, a combined therapy with indomethacin and captopril was needed to discontinue intravenous fluids and improve weight gain.
KeywordsBartter syndrome Sensorineural deafness Captopril Indomethacin Nimesulide Furosemide Hydrochlorothiazide
- 2.Birkenhager R, Otto E, Schurmann MJ, Vollmer M, Ruf EM, Maier-Lutz I, Beekmann F, Fekete A, Omran H, Feldmann D, Milford DV, Jeck N, Konrad M, Landau D, Knoers NV, Antignac C, Sudbrak R, Kispert A, Hildebrandt F (2001) Mutation of BSND causes Bartter syndrome with sensorineural deafness and kidney failure. Nat Genet 29:310–314PubMedCrossRefGoogle Scholar
- 4.Vollmer M, Jeck N, Lemmink HH, Vargas R, Feldmann D, Konrad M, Beekmann F, van Den Heuvel LP, Deschenes G, Guay-Woodford LM, Antignac C, Seyberth HW, Hildebrandt F, Knoers NV (2000) Antenatal Bartter syndrome with sensorineural deafness: refinement of the locus on chromosome 1p31. Nephrol Dial Transplant 15:970–974PubMedCrossRefGoogle Scholar
- 5.Estevez R, Boettger T, Stein V, Birkenhager R, Otto E, Hildebrandt F, Jentsch TJ (2001) Barttin is a Cl− channel beta-subunit crucial for renal Cl− reabsorption and inner ear K+ secretion. Nature 414:558–561Google Scholar