Hearing Loss: A Family Affair?

Many things run in families – hair color, eye color and the risk of certain diseases. Not surprisingly, hearing loss can run in families also. In infants who are born deaf, about half have an associated genetic component. Hearing loss is the most common birth defect in developed countries, although not all hearing loss is genetic in origin. Infants born with hearing loss of any cause have congenital hearing loss. Other causes of hearing loss in newborns that are not genetic may include infections that mom had when the baby was in utero, being born too early or even having a traumatic delivery. Hearing loss that develops after the baby is born is called acquired hearing loss, which can be genetic or due to other problems or illnesses.

Is it possible to identify the genes that cause hearing loss? Unfortunately in many cases, hearing loss can’t be pinned down to a single gene or genes. In fact, a thousand or more mutations or changes in upwards of 60 genes are linked with hearing loss. With developments in genetic testing, some, but not all, of these gene mutations have been described, but there is still more to learn. Also, genes may interact with the environment to create a hearing loss.

Genetic hearing loss may manifest in several ways: malformations of the outer ear (the visible part you can see) or problems with middle or inner ear where sound is processed. Hearing loss can also be one part of a genetic syndrome where other systems of the body are affected, and hearing loss is only one symptom.

The Role of Genetic Testing

It’s possible to get genetic testing to see if you carry a gene that predisposes your offspring to hearing loss, but this type of testing has limitations. For one, not all the genes associated with hearing loss have been identified, and even if you have a genetic mutation, you can’t always say with certainty that the mutation that is identified caused the hearing loss. Furthermore, because of the way genes are passed from parent to child, a child can have genetic hearing loss even if no one else in their family is affected. In a case like this, both parents are carriers of the gene and the gene is recessive. If hearing loss runs in your family, especially in childhood, talk to a hearing care professional about the pros and cons of genetic testing.

References:

• Hearing Health Foundation. “The Case for Genetic Testing”