Everyone knows that injuries, noise exposure and selected diseases can result in hearing loss, but are there also genetic factors involved? Without a doubt, the answer is “Yes.” Genetic abnormalities actually lay at the root of most types of hearing loss. In the developed world, hearing loss is considered the most frequent genetic birth defect.
A quick lesson in genetics. They way your body functions and looks is governed by the genetic code of your DNA – your genes. Hearing is a sophisticated body function which is known to involve no less than 100 distinct genes. Hearing loss can result from any one of these genes being missing or modified. When an individual carrying these irregular gene sequences has a child, the abnormal gene or genes are often passed down to the child too.
Genetic hearing loss variations. Inherited hearing loss can affect the inner ear, outer ear or both. The hearing loss can be sensorineural, conductive or mixed. Additionally, some genes result in hearing loss before a person learns to talk (prelingual hearing loss), and other genes cause hearing impairments that appear after speech is learned (postlingual hearing loss). Some of the genetic conditions are common enough to have names. For example, Usher syndrome affects about 50 % of the deaf-blind population. Waardenburg syndrome is another common condition that affects hearing in the inner ear but also causes streaks of white hair, pale skin, and light or multi-colored eyes.
Will kids inevitably inherit hearing loss? Just because a parent has hearing loss, doesn’t inevitably mean the child will have hearing loss too. Most genes related to hearing loss are recessive, which means that even though an individual has an irregular gene, that gene will not always cause a problem as long as a normal copy is received from the other parent. Even if both parents have hearing loss, their children may still not be affected by hearing loss because different genes may be responsible in each parent. Individuals concerned with hereditary hearing loss can see a doctor for genetic testing that can help determine potential risks.