Genetics, hearing loss and rare diseases
If your parents or grandparents lost their hearing at an early age or have always had trouble with balance or dizziness, it’s important to know why. Some types of hearing loss are the result of aging or noise damage, but it also can be inherited in a number of ways.
Can you inherit hearing loss?
Turns out that, yes, hearing loss—including age-related hearing loss—is influenced by your genes. In other words, you can inherit an increased risk of hearing loss as you get older.
While more research is needed, a large study of 376 Caucasian families found that "genetic factors play a large role in age-related hearing loss." Also, while overall men have more hearing loss (largely due to exposure to noise in traditionally male-dominated work sectors, such as aviation or the military), the study found that women's hearing loss was more influenced by genes than men.
However, it's hard to weed out a lot of factors that can affect studies like this—notably, the behaviors that expose people to hearing damage. Since families often share occupations or habits, it's not 100% possible to know if it's the genes or the shared behaviors that are linked to hearing loss. It's probably a combination of both.
It’s important to know family history
According to the Centers for Disease Control (CDC), knowing your family’s history of chronic disease is the first step toward reducing your risk of developing it, too. The CDC recommends making a list of immediate family members, then asking them if they’ve had any chronic or serious diseases as well as what age they developed it. Once you know the answers, share it with other family members and your family physician. This information can help your doctor determine which screening tests you need and at what age these screenings should begin.
Otosclerosis is the abnormal bone growth of the middle ear, which usually affects the stapes bone. Symptoms of the disorder include gradual hearing loss, most often difficulty hearing low-pitched sounds. Others may experience dizziness, balance issues or tinnitus.
The odds of developing otosclerosis vary depending upon the family’s history with the disease and is often passed down from parent to child. Children who have one parent with otosclerosis have a 25 percent chance of developing the disease. The risk rises to 50 percent if both parents have the disease. White, middle-aged women are most at risk.
The disorder typically causes conductive hearing loss, which can often be corrected with surgery. Less commonly, otosclerosis causes damage to the sensory cells and nerve fibers in the inner ear, causing sensorineural hearing loss.
Many rare diseases can cause hearing loss
Scientists have identified 7,000 diseases that are considered rare. As defined in the U.S by the Orphan Drug Act of 1983, rare diseases each affect fewer than 200,000 people. However, up to 30 million Americans live with a rare disease. Some of these are inherited, and some have no known genetic cause.
At least 400 of these rare syndromes include hearing loss as a symptom, according to BabyHearing.org. They can lead to different types of hearing loss, the main types being sensorineural and conductive.
The degree of loss can vary widely from person to person. For some people, hearing aids will be sufficient. For others, cochlear implants and/or learning speechreading and American Sign Language will be recommended. In many cases, a rare disease can cause multiple anatomical and functional changes in the ears, requiring surgery.
Edith Veitch was 10 when an audiologist diagnosed childhood hearing loss and fitted her with aids.
Her mother, Margo, a community college instructor in Illinois, is unsure when the hearing loss set in. “We don’t have [hearing loss] in the family so we weren’t looking for it,” she said.
Her family opted for a deaf and hard-of-hearing program—the classes were small and it wasn’t clear how quickly her hearing might deteriorate. Many of her classmates have cochlear implants or rely mainly on ASL. But, Edith's hands are small and it is difficult for her fingers to form shapes. “When her peers sign to her, she was signing back, but she has become more self-conscious,” Veitch said.
Eventually her family learned that Edith has Myhre syndrome, a rare disorder of the connective tissue. Fortunately, as with many rare diseases, hearing aids have been an effective treatment.
"She appreciates being able to hear,” Veitch said of her daughter's hearing aids.
Detecting rare diseases
Newborn hearing screening
Because of state programs aided by the federal government, nearly all American babies have a hearing test within the first month of life. About two or three out of every 1,000 newborns in the U.S. have a detectable hearing loss in one or both ears.
The hearing loss may be a sign of a rare disease (but not always). Babies with Mondini dysplasia, for example, are born with one and a half coils in the cochlea instead of the standard two, in either one or both ears. Most children with this condition have profound hearing loss. They may need a surgical repair, as well as a cochlear implant, but some can benefit from hearing aids. Babies with KID syndrome, Donnai-Barrow syndrome, and Wildervanck syndrome—among other rare diseases—may have hearing loss.
Sometimes the loss is not present at birth but develops soon after. Babies with the most common and severe form of Krabbe disease develop symptoms in the first six months, which include fevers, muscle weakness and hearing and vision loss.
Some diseases surface later in childhood
And sometimes, as with Edith, the hearing loss comes much later. People with Alport syndrome, for example, often lose hearing in late childhood or early adolescence and may be treated with hearing aids. Similarly, people with Alström syndrome tend to have progressive hearing loss in both ears that may begin in childhood and be treated with hearing aids.
Turner syndrome: Frequent ear infections can be a clue
Parents of girls who don’t appear to be developing at the same rate as their peers and who experience frequent ear infections may want to ask their family doctor about Turner syndrome, a rare genetic condition which affects one out of every 2,000 to 4,000 female births. Early diagnosis is key, as those affected have higher incidences of hearing loss, heart, liver and kidney abnormalities and autoimmune disorders.
How Turner syndrome affects hearing
Girls and women with Turner syndrome have a high prevalence of problems with their hearing and should be evaluated frequently. Hearing health problems that can occur include:
Children who develop hearing loss may have Pendred syndrome, a genetic disorder inherited from the parents that may also include balance and thyroid problems. Families with medical histories of early hearing loss or those with a history of goiters and hearing loss may be carriers of the mutated gene causing this recessive trait. According to the National Institutes of Deafness and Other Communication Disorders (NIDCD), this disorder accounts for five to ten percent of all inherited hearing loss.
An otolaryngologist can diagnose Pendred syndrome. Although there is no cure, it can be treated. Depending on the severity of the hearing loss, the affectec person may benefit from wearing hearing aids or receiving a cochlear implant.
Usher syndrome includes three types of hearing loss, depending on the onset and severity of symptoms.
People who have hearing loss and retinitis pigmentosa (RP), an eye disease, may have a disorder known as Usher syndrome. According to NIDCD, Usher syndrome accounts for 50 percent of hereditary deaf-blindness cases, a type of dual-sensory impairment.
There are three types of Usher syndrome, each inherited as an autosomal recessive disorder from the parents:
Although there is no cure for Usher syndrome, its symptoms can be treated or managed. Treatment for hearing loss may include hearing aids or cochlear implants along with assistive listening devices and auditory training.
Other rare diseases linked to hearing loss
Many rare disorders can include hearing loss as a symptom. Some examples include:
Symptoms can be unpredictable
Symptoms can vary widely in severity among people with the same disorder. And intellectual ability may or may not be affected. For example, children with Carpenter syndrome may be of normal intelligence but it is common for them to have an intellectual disability and sometimes hearing loss.
Such is the case with Myhre syndrome, the condition that Edith has. At least 80 percent of people with it have a hearing impairment, as well as intellectual disability and stiff joints.
Although Edith’s hearing did decline, she does not have a profound loss. She happily wears her hearing aids, even at home.
When she took an art class with 30+ student, her mother noted, “many didn’t know she had hearing aids."
For more information
Although the above disorders are rare, it’s important to know your family’s hearing health history and share it with your family physician as well as your hearing healthcare professional.
For more information on rare diseases, see the National Organization for Rare Disorders (NORD).