Nonsyndromic Hearing Loss and Deafness, DFNA3 – RETIRED CHAPTER, FOR HISTORICAL REFERENCE ONLY

Excerpt

NOTE: THIS PUBLICATION HAS BEEN RETIRED. THIS ARCHIVAL VERSION IS FOR HISTORICAL REFERENCE ONLY, AND THE INFORMATION MAY BE OUT OF DATE.

Clinical characteristics: Nonsyndromic hearing loss and deafness, DFNA3 is characterized by pre- or postlingual mild-to-profound progressive high-frequency sensorineural hearing impairment. Affected individuals have no other associated medical findings.

Diagnosis/testing: Diagnosis of DFNA3 depends on molecular genetic testing to identify a heterozygous pathogenic variant in GJB2 (encoding connexin 26 [Cx26]) or GJB6 (encoding connexin 30 [Cx30]).

Management: Treatment of manifestations: Early diagnosis, habilitation with hearing aids or cochlear implantation, and educational programming diminishes the likelihood of long-term speech or educational delay.

Surveillance: Semiannual examination by a physician who is familiar with hereditary hearing impairment; repeat audiometry to confirm stability of hearing loss

Agents/circumstances to avoid: Environmental exposures known to cause hearing loss, such as repeated loud noises.

Evaluation of relatives at risk: Once the GJB2 or GJB6 pathogenic variant has been identified in an affected family member, molecular genetic testing can be used to clarify the genetic status of at-risk relatives in infancy or early childhood so that appropriate early support and management can be provided.

Genetic counseling: DFNA3 is inherited in an autosomal dominant manner. Most individuals diagnosed as having DFNA3 have a deaf parent. Each child of an individual with DFNA3 has a 50% chance of inheriting the GJB2 or GJB6 pathogenic variant. Once the GJB2 or GJB6 pathogenic variant has been identified in a family member with DFNA3, prenatal testing for a pregnancy at increased risk and preimplantation genetic testing are possible.