Deafness, Autosomal Recessive 84

Alternative Names

  • DFNB84
  • Deafness, Autosomal Recessive 84, with Vestibular Dysfunction
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WHO-ICD-10 version:2010

Diseases of the ear and mastoid process

Other disorders of ear

OMIM Number

613391

Mode of Inheritance

Autosomal recessive

Gene Map Locus

12q21.31

Description

Sensorineural hearing loss (SNHL) is the most prevalent genetic sensory defect in humans. It is estimated that globally 1:1000 children born have profound hearing loss. Non-syndromic SNHL accounts for approximately 70% of hereditary hearing loss and 80% of the non-syndromic SNHL cases have an autosomal recessive mode of inheritance (ARNSHL), also known as DFNB. To date, more than 100 gene loci have been implicated in DFNB.

DFNB84 is clinically characterized by progressive, bilateral sensorineural hearing loss, with prelingual onset. Neurologically, it is characterized by mildly delayed motor development due to vestibular dysfunction.

Molecular Genetics

DFNB84 is caused by mutation in the protein-tyrosine phosphatase receptor-type Q (PTPRQ) gene located on chromosome 12q21.31.

Epidemiology in the Arab World

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Other Reports

Morocco

Schraders et al. (2010) reported a consanguineous Moroccan family with two male sibs affected with bilateral, symmetric, sensorineural, progressive, and likely congenital hearing loss. Electronystagmography in caloric and rotary testing in this family demonstrated impaired vestibular function. At the molecular level, Schraders et al. (2010) identified a homozygous missense mutation (c.1369A>G; p.Arg457Gly) in the PTPRQ gene in the affected sibs of this family.

Palestine

Shahin et al. (2010a) and Shahin et al. (2010b) reported two consanguineous Palestinian families in which affected individuals had moderate to severe prelingual, bilateral, autosomal recessive non-syndromic hearing loss (NSHL). There were no signs of conductive hearing loss, as measured by air and bone conduction thresholds. None of the affected individuals had any vision problems. Shahin et al. (2010a) found in these two families linkage to a 12.5-Mb region on chromosome 12q (lod score of 3.45), designated DFNB84. Later, Shahin et al. (2010b) discovered that these two families are originated from the same extended kindred. Shahin et al. (2010b) identified a homozygous nonsense mutation in the PTPRQ gene (c.1285C>T; p.Q429X) in the affected individuals in this extended kindred.

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