The genetics behind hearing loss are complex, largely because the auditory system is extremely intricate and there are so many factors that can affect it. Here is a breakdown of some of the ways hearing loss can be passed through families:
Syndromic Hearing Loss
Hearing loss can occur as a symptom of another genetic condition; in fact, about 30 percent of cases of inherited hearing loss are associated with a syndrome. These syndromes include:
- DiGeorge syndrome
- Treacher-Collins syndrome
- Usher’s syndrome
- Pendred syndrome
Hearing loss associated with other symptoms, like the syndromes listed above, is called “syndromic” hearing loss.
Non-Syndromic Hearing Loss
There are many genes involved in developing the auditory system. If one of these genes does not develop properly, hearing loss can result. Sometimes gene mutations occur in an individual and no one else in the family; other times, specific gene mutations show up in multiple family members. When this is the case, hearing loss is said to be familial.
Certain types of hearing loss are not evident until later in life because they are “turned on” or expressed when a person comes into contact with environmental factors.
When hearing loss is the result of mutated genes (a common one is the GJB2 mutation) and presents with no other symptoms, it is said to be “non-syndromic.” Non-syndromic hearing loss is more difficult to detect in babies, as there are no other symptoms to help identify a problem, and accounts for about 70 percent of cases of inherited hearing loss.
Who is a Carrier for Genetic Hearing Loss?
Not everyone who inherits a gene mutation experiences hearing loss – these people are called carriers. While a person who carries the gene mutation may not experience hearing problems themselves, they are likely to pass the mutation along to their offspring. In fact, it is fairly common for babies born with inherited hearing loss to have two parents with normal hearing.
Late-in-Life Hearing Loss
You might expect inherited hearing loss to present itself only at birth, but this isn’t always the case. Late-onset hearing loss has been associated with several inherited gene mutations, such as the DFNA10 gene. Mutations in this gene can cause progressive hearing loss later in adulthood.
For more information about genetic hearing loss or to schedule a hearing screening, call SW Idaho ENT today!