Molecular basis of DFNB73: mutations of BSND can cause nonsyndromic deafness or Bartter syndrome.
BSND encodes barttin, an accessory subunit of renal and inner ear chloride channels. To date, all mutations of BSND have been shown to cause Bartter syndrome type IV, characterized by significant renal abnormalities and deafness. We identified a BSND mutation (p.I12T) in four kindreds segregating nonsyndromic deafness linked to a 4.04-cM interval on chromosome 1p32.3. The functional consequences of p.I12T differ from BSND mutations that cause renal failure and deafness in Bartter syndrome type IV. p.I12T leaves chloride channel function unaffected and only interferes with chaperone function of barttin in intracellular trafficking. This study provides functional data implicating a hypomorphic allele of BSND as a cause of apparent nonsyndromic deafness. We demonstrate that BSND mutations with different functional consequences are the basis for either syndromic or nonsyndromic deafness.
Riazuddin
Saima
S
Section on Human Genetics, Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, NIH, Rockville, MD 20850, USA.
Anwar
Saima
S
Fischer
Martin
M
Ahmed
Zubair M
ZM
Khan
Shahid Y
SY
Janssen
Audrey G H
AG
Zafar
Ahmad U
AU
Scholl
Ute
U
Husnain
Tayyab
T
Belyantseva
Inna A
IA
Friedman
Penelope L
PL
Riazuddin
Sheikh
S
Friedman
Thomas B
TB
Fahlke
Christoph
C
D000293:Adolescent; D000328:Adult; D001299:Audiometry; D001477:Bartter Syndrome / Q000235:genetics*; D018118:Chloride Channels / Q000235:genetics*; D019457:Chromosome Breakage; D002874:Chromosome Mapping; D002878:Chromosomes, Human, Pair 1; D004252:DNA Mutational Analysis; D003638:Deafness / Q000235:genetics*; D005260:Female; D008040:Genetic Linkage; D005819:Genetic Markers; D006239:Haplotypes; D006720:Homozygote; D006801:Humans; D008297:Male; D018895:Microsatellite Repeats; D008875:Middle Aged; D009154:Mutation; D010375:Pedigree; D020641:Polymorphism, Single Nucleotide; D055815:Young Adult
C440005:BSND protein, human; D018118:Chloride Channels; D005819:Genetic Markers