Advances in genetics have enabled scientists to identify genes that cause hearing loss. A substantial portion of people with nonsyndromic hearing loss
have Connexin 26 disorder. This is a complex genetic disorder that leads to flawed copies of the gap junction beta 2 (GJB2) gene, which normally instructs a protein, Connexin 26 (CX26).
Everyone has two copies of this gene, but if each birth parent has a flawed copy of the GJB2/Connexin 26 gene, the baby may be born with a hearing loss. The hearing loss occurs because the mutation is suspected of disrupting potassium flow in the inner ear.
Who Has Connexin 26 Mutations?
Connexin 26 mutations occur primarily in Caucasians, Ashkenazi Jews, and some Asian people.
Testing for Connexin 26 Deafness
People can be tested to see if they are carriers of the flawed version of the gene. Another gene, CX 30, has also been identified and is responsible for some hearing loss. Similar testing can be done to determine if an already-born child's hearing loss is related to Connexin 26.
Additional Resources on Connexin 26
Articles about Connexin 26 and deafness have appeared in genetics journals, such as the Journal of Medical Genetics (http://jmg.bmjjournals.com/ allows search and downloading of articles), and Human Genetics. There is a detailed scientific report on the web at cesil.com
. The National Library of Medicine's PubMed database has material on Connexin 26 mutations.
Articles on Connexin 26 and Deafness
The Alexander Graham Bell Association for the Deaf and Hard of Hearing had an article, "The Genetics of Deafness: Connexin 26 Testing" by Heidi Rehm, in its Volta Voices
magazine, Volume 7 Number 6, November/December 2000. This illustrated article explains in a mix of scientific language and layman's English about how Connexin 26 causes deafness, and about how it is screened.