The Role Of Genetics In Hearing Loss

Hearing loss is a condition that can affect anyone of any age at any time. It can impact life in a diverse amount of areas, such as education, employment and social status. Aging and noise exposure are primary causes of hearing loss, but your genes could play a role, too.

Before launching into the main discussion, it is worth noting that genetics is not always destiny. While some people might have a proclivity to developing hearing loss, it doesn’t mean they will. Epigenetics also matter in most age-and noise-induced hearing loss cases, as in most degenerative conditions.

Why Do Some People Inherit Hearing Loss?

Some forms of hearing loss result from a single genetic mutation, while others require multiple genes to express incorrectly. In some cases, the interactions are complex and researchers can’t always identify the root cause of deafness.

Hearing health professionals classify two main types of genetic hearing loss:

1. Syndromic hearing loss: Syndromic hearing loss means that the hearing impairment is associated with other symptoms or medical conditions that affect other parts of the body. For instance, patients may have Usher syndrome, a genetic disorder that causes deafness from birth and vision loss.
2. Non-syndromic hearing loss: Non-syndromic hearing loss refers to patients with a hearing impairment that is not accompanied by any other symptoms or medical conditions. Approximately two-thirds of genetic cases fall into this category.

Therefore, some people inherit hearing loss because of the genes they get from their parents. According to estimates, about 50-60% of hearing loss in babies is due to genetic causes. However, these hearing loss genes can turn on later in life, affecting adults, too.

Which Genes Cause Hearing Loss?

Hundreds of gene mutations can cause hearing loss in children and adults without requiring environmental damage or aging to occur first. Issues with connexin 26 (Cx26) are among the most common. This complex makes a protein that lets the body form channels in the inner ear that regulate the movement of ions critical for hearing. Some mutations cause this gene (GJB2) to disrupt channel function, leading to severe hearing impairment. Researchers believe it is responsible for around 40 percent of hearing loss in newborns with non-syndromic hearing loss.

Another example of a gene that can cause non-syndromic hearing loss is MT-RNR1. This gene is in the mitochondria – energy-producing organelles inside cells. Mutations in MT-RNR1 can affect energy production and damage the cells in our inner ear. Sound-sensitive biological machinery cannot interpret incoming signals, causing hearing loss. (This mutation, like color blindness, only comes from mothers).

Lastly, the WFS1 gene can cause hearing loss and the development of Wolfram syndrome, a rare disorder that affects multiple body systems, including the eyes, pancreas and brain. With this condition, hearing loss starts in adolescents and worse during adulthood.

Which Genes Put People at Risk of Developing Hearing Loss?

The genes discussed in the last section cause hearing loss directly. However, there are others (analogous to the BRCA genes for breast cancer) that increase the likelihood of hearing loss. For instance, individuals with a family history of hearing loss are more likely to carry unwanted mutations. There may be dozens of these in any individual, all interacting to increase hearing loss likelihood. Tests are available for these patients to see if they are at risk and whether they should make lifestyle modifications.

Other individuals may have an assortment of unique mutations that predispose them to lose their hearing. Again, these people should live a healthy lifestyle and avoid loud noises that could adversely affect their ears.

Genetic Testing for Hearing Loss

Genetic testing is a powerful tool for identifying the cause and inheritance pattern of hearing loss in families and individuals. Testing works by analyzing DNA samples from blood or saliva and then combing through them for specific mutations responsible for hearing loss.

Genetic testing comes with a host of benefits, including:

• Confirming or ruling out a diagnosis
• Identifying complications associated with various conditions
• Facilitating early intervention
• Connecting people to support groups
• Informing reproductive choices

Testing is particularly valuable for parents because it helps them identify their child’s needs from an early age. If genetic testing indicates a young person is likely to develop a hearing impairment, they can put strategies in place today to manage it.

If you’d like to learn more about the genetic component of hearing loss, then get in touch with our team of hearing health professionals at Park Place Hearing Center. Call (707) 283-7853 to arrange a consultation.