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Genetic Testing for Deafness Overview

last modified on: Tue, 04/17/2018 - 13:05

Genetic Testing for Deafness Overview

See also: Congenital Hearing Loss, OtoSCOPE® - Genetic Testing

See Flow Diagram Below for Summary

Key Information:

  • Genetic deafness comprises the majority of congenital deafness but environmental causes need to be excluded first
  • 70% of genetic deafness is non-syndromic (i.e. there are no other associated syndromic phenotypic features)
  • There are more than 65 known non-syndromic deafness genes
  • Theere are more than 400 estimated syndromes with associated deafness
  • Genetic testing can be performed on a single-gene basis or with multi-gene panels

Genetic Testing for Syndromic Deafness

  • Genetic testing is typically single-gene testing and is based on phenotypic findings
  • Most common syndromes include Pendred Syndrome, Waardenburg Syndrome, BOR, and Usher syndrome
  • Non-syndromic mimics are syndromic forms of deafness for which the syndromic phenotype develops later in life than birth. Therefore the child may appear to have isolated genetic deafness when in fact the blindness (in Usher syndrome), for example has not manifested yet
  • Several comprehensive non-syndromic testing panels include non-syndromic hearing loss mimic genes (see below)
  • Follow-up tests (i.e. retinography, EKG, renal ultrasound) may be indicated
  • See Genetest.org and search for specific syndromic form of deafness

Comprehensive Genetic Testing for Non-syndromic Deafness

  • Comprehensive gene panels have been developed to improve diagnosis for non-syndromic deafness
  • These panels often include the most common non-syndromic hearing loss mimics (i.e. Usher, Pendred, and BOR Syndrome genes)
  • OtoSCOPE, a test developed at the University of Iowa, is an example of one of these tests (See Genetests multi-gene panels for a complete listing of other multi-gene panels for non-syndromic hearing loss and also Shearer et al 2010, Shearer et al 2013)
  • A genetic diagnosis of non-syndromic hearing loss precludes further follow-up tests
     

 

Suggested Reading

 

  • Shearer, et al. "Comprehensive genetic testing for hereditary hearing loss using massively parallel sequencing." Proceedings of the National Academy of Sciences 107.49 (2010): 21104-21109.
  • Shearer, et al. "Advancing genetic testing for deafness with genomic technology." Journal of medical genetics (2013).