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GENATLAS PHENOTYPE
last update : 04-09-2013
Symbol DFNB1
Location 13q12.11
Name neurosensory deafness 1
Corresponding gene GJB2 , GJB6
related resource Genetics hearing impairment
Other symbol(s) NSRD1
Main clinical features
  • non syndromic, prelingual, mild to profound with a large variation among families and a loss of hearing in the high frequency range characteristic in children with GJB2 impairment, stable, associated with sloping of flat audiometriccurves and a radiologically normal inner ear, responsible of a majority of non syndromic deafness in a number of populations
  • vestibular dysfunction appears to be common in DFNB1 (PMID: 21465647))
  • in 10 p100 of cases, temporal bone abnormalities (PMID: 21298644))
    • Genetic determination autosomal recessive
    Function/system disorder ear
    Type disease
    Gene product
    Name . gap junction protein beta 6 (connexin 30) . gap junction communication channel component (GJB2)
    Mechanism(s)
    Gene mutationChromosome rearrangementEffectComments
    deletion   unknown (35delG) occuring in a stretch of six G, accounting for 28 to 63p100 of mutations in Caucasoids with an higher frequency in southern than in central and northern Europe and an overall carrier frequency of 1/51 in European populations
    deletion   unknown (235delC) in Japanese and (167 delT)in Jewish Askenazi
    deletion   under-expression del(chr13:19,837,344-19,968,698whose proximal breakpoint lies more than 100 kb upstream of the transcriptional start sites of GJB2 and GJB6
    Remark(s) phenotypic variability in 35delG homozygous patients cannot be explained by the effect of one major modifier gene (Hilgert (2009)
    • Genotype/Phenotype correlations
  • GJB2 responsible of about 40% of neurosensory deafness, and rare point mutations resulting in loss of gap junction mediated intercellular communication
  • homozygous for 35delG have significantly more sever deafness as heterozygous 35 delG/non-35delG