Think about the traits that have been passed along through your family. You, your mother and your grandmother might all have blue eyes. Your children might have the same curly hair as you. All of your cousins might be tall or have a similarly shaped nose. You and your siblings might even have the same freckles.
While the traits look different for every family, the reach of our genes goes beyond the surface, extending to medical conditions that can be passed from parents to their children and descendants. This even includes hearing loss; there are several heritable genetic conditions that affect our ability to hear.
This passing of genetic conditions means that disabilities and their related side effects, which includes hearing loss, can play a role in later generations’ lives. For grandparents and parents, understanding the effects that genetics might have on future generations ensures that they can also pass on the knowledge and tools to more successfully identify and deal with inherited conditions.
Found in every single cell of the human body, genes are the most basic unit of heredity information passed down from parent to child. They form specific patterns to make up our DNA and instruct the body on how to grow and develop. Through the sharing of genetic information, parents pass on characteristics like hair and eye color, as well as physiological attributes and conditions.
Hearing loss is among the conditions that can be passed down through genetic information. It can stem from a mutation or absence of genes that affect the way the ears are physically formed, or the way they function. If more than one person in a family has genetic hearing loss, it’s known as “familial,” as it runs in the family.
If hearing loss is in the parents’ genes, their children’s hearing can be evaluated at birth to determine if a hearing loss does exist. The specifics of an inherited genetic condition will dictate when, how, and the amount of hearing loss. Hearing loss when present at birth is known as congenital hearing loss. Fifty to 60% of congenital hearing loss stem from genetic causes. ²
However, just because the genes are in your family, doesn’t necessarily mean that every family member will experience hearing loss. As with physical traits, not every family member inherits every gene. Not everyone will inherit the gene mutation or medical condition that causes hearing loss, or its effects and incidence might vary by a person’s sex. Each case is unique, but by understanding the role genetics plays in our bodies and our medical histories, we can better prepare to manage our hearing in the future..
To understand the conditions and diseases that cause hearing loss, it's important to first look at the types of hearing loss and how each affects sound processing in the body. Each type correlates to a specific region or condition and affects your hearing health in its own way. The type of hearing loss you have will also determine which treatment options are best for you.
This kind of hearing loss most often happens as a result of an obstruction in the outer or the middle ear, preventing sound from traveling to the inner ear. Symptoms of this type of hearing loss include muffled hearing, dizziness, draining of the ear and pain, tenderness, or a "full" feeling in the ear.
As its name suggests, mixed hearing loss is a combination of both sensorineural and conductive hearing loss. In many cases, it takes place when there is damage occurring over time as well as some trauma or disease that damages the ear. Mixed hearing loss symptoms include difficulty hearing specific consonants, tinnitus or problems understanding conversation in crowded spaces, a fullness sensation in the ears, and/or intermittent hearing loss.
Hereditary hearing loss is almost always sensorineural, not conductive or miixed.
Several genetic medical conditions are associated with hearing loss. Let’s explore some of these conditions and how they affect hearing:
Otosclerosis is a medical condition that causes abnormal bone growth in the middle ear, resulting in conductive hearing loss in one or both ears. This spongy bone growth prevents the ear bones from vibrating normally to conduct sound waves. Considered the most common cause of middle-ear hearing loss in young adults, otosclerosis typically begins in early to mid-adulthood and is more prevalent in women. Symptoms include slowly worsening hearing loss, tinnitus and vertigo.
Neurofibromatoses refer to a group of genetic disorders that cause tumors to form on nerve tissue. While these conditions aren’t specific to the ears, tumors can develop anywhere in the nervous system, including the auditory nerve. Generally, these tumors are cancerous, but can become malignant. There are two types of neurofibromatosis, known as NF1 and NF2. Type 2 is much less common than NF1, but is more associated with hearing loss. Symptoms of NF2 include gradual hearing loss, tinnitus, poor balance and headaches, stemming from the development of slow-growing tumors in both ears. The signs of this sensorineural condition generally appear in late teen and early adult years.
Usher syndrome is a rare genetic condition that impairs both hearing and vision. Caused by mutations in the genes that result in the abnormal development of the hair cells of the inner ear, people with the syndrome are usually born with it and diagnosed in early childhood. There are three types: People living with type 1 usually have profound hearing loss at birth; people with type 2 have moderate to severe hearing loss early in life; and people with type 3 have normal hearing at birth, but experience hearing loss beginning in childhood. Symptoms depend on the level of hearing loss at birth, but include difficulty hearing, adjusting to light changes and balancing.
Pendred syndrome is a genetic hearing loss disorder that primarily affects children. Children who are born with the syndrome might start losing their hearing at birth, or by the time they reach 3 years old, with their hearing worsening in both ears over time. This rare syndrome can be caused by a mutation inherited from the parents, resulting in malformations of the inner ear. Because Pendred syndrome is also related to the thyroid, symptoms include the development of a goiter (swelling of the thyroid). Other symptoms include balance and orientation problems.
Despite the heritability of certain causes of hearing loss, there are ways to address and manage it. Treatments depend on the specifics of your condition, but there are ways to manage your hearing health that allow you to live life to the fullest. Here are a few first steps you can take:
Hearing loss can be genetic with or without a shared family history of hearing loss. Genetic conditions don’t always present in the same way for everyone, but they could still be the cause of hearing loss. Whether you’re experiencing unexpected hearing loss or know that it runs in your family, a genetic test can be useful in determining if anyone else in the family carries the mutation and if other health problems could develop.
Your primary care provider (PCP) is a great resource for discussing your medical history and how your genes might be influencing your hearing loss. With a full understanding of your medical history—including family history—they will be able to assess what factors are in play. You might need to see a specialist for some conditions, but your PCP can serve as your first resource.
A baseline hearing test is an important tool for understanding both your current level of hearing loss and gauging howo your hearing evolves in the future. Your audiologist will be able to assess what type of hearing loss you are experiencing. They will help you understand your test results and make a plan to manage your hearing loss. Schedule your appointments regularly to properly assess and treat your condition.
¹https://www.cdc.gov/ncbddd/hearingloss/genetics.html
²https://resonanceaudiology.com/hearing-loss-hereditary/
³https://www.cdc.gov/ncbddd/hearingloss/genetics.html
