Pendred syndrome

• Article
• 2021-03-02

Pendred syndrome is a genetic condition that causes early hearing loss in children. It can also affect the thyroid gland and sometimes cause balance problems. The syndrome is named after Vaughan Pendred, the doctor who first described people with the condition.

Children born with Pendred syndrome may begin to lose their hearing at birth or by the time they are three years old. Usually their hearing will deteriorate over time. The hearing loss often comes on suddenly, although some people will regain hearing later. Eventually, some children with Pendred syndrome become completely deaf.

Almost all children with Pendred syndrome have bilateral hearing loss, which means hearing loss in both ears, although one ear may have more hearing loss than the other.

Hearing loss in children has many causes. Researchers believe that in the United States, 50 to 60 percent of cases are due to genetic causes and 40 to 50 percent of cases are due to environmental factors. Healthcare professionals use a variety of clues, such as when the hearing loss begins and whether there are anatomical differences in the ears, to help determine whether a child has Pendred syndrome or some other form of progressive deafness.

How does Pendred syndrome affect other parts of the body?

Pendred syndrome can cause the thyroid gland to enlarge. An enlarged thyroid gland is called a goiter. The thyroid gland is a small, butterfly-shaped gland on the front of the neck, just above the collarbones. The thyroid gland plays an important role in how the body uses energy from food. In children, the thyroid gland is important for normal growth and development. However, children with Pendred syndrome rarely have problems growing and developing properly, even if their thyroid gland is affected. Their thyroid hormone levels are usually normal.

People with Pendred syndrome are significantly more likely than the general population to develop a goiter during their lifetime, although not everyone with Pendred syndrome will develop a goiter. The typical age at which a goiter develops is adolescence or early adulthood. If a goiter grows large, there may be problems breathing and swallowing. In this case, a health professional should monitor the goiter and decide if treatment is needed. People with Pendred syndrome may need to see an endocrinologist, a specially trained physician who is familiar with diseases and conditions involving the endocrine system, including the thyroid gland.

Pendred syndrome can also affect the vestibular system, which controls balance. Some people with Pendred syndrome will show vestibular weakness when their balance is tested. However, the brain is very good at making up for a weak vestibular system, and most children and adults with Pendred syndrome don't have a problem with their balance or have trouble performing routine tasks. However, some babies with Pendred syndrome may start walking later than other babies.

Scientists don't know why some people with Pendred syndrome develop a goiter or have balance problems and others don't.

What Causes Pendred Syndrome?

Pendred syndrome can be caused by changes or mutations in a gene called SLC26A4 (formerly known as the PDS gene) on chromosome 7. Because it is a recessive trait, a child must inherit two mutated SLC26A4 genes - one from each parent - have Pendred syndrome. Since the child's parents are only carriers of a mutation in the SLC26A4 gene, there are no health consequences for them.

Couples concerned that they could pass on Pendred syndrome to their children may want to do genetic testing. A possible sign that someone is a carrier of a mutated SLC26A4 gene is a family history of early hearing loss. Another sign is a family member who has both a goiter and hearing loss. However, often there is no family history of Pendred syndrome in the families of children with the condition. A mutation in the SLC26A4 gene can be determined by genetic testing of a blood sample.

The decision to have a genetic test done is a complicated one. Most people talk to a genetic counselor who is trained to handle theme help to weigh the medical, emotional, and ethical considerations of testing. A genetic counselor is a health professional who provides information and support to people (and their families) with a genetic condition or at risk of a genetic condition.

How Is Pendred Syndrome Diagnosed?

An otolaryngologist (a physician specializing in diseases of the ear, nose, throat, head, and neck) or a clinical geneticist will consider hearing loss, inner ear structures, and sometimes the thyroid gland when diagnosing Pendred syndrome. He or she will evaluate the timing, amount, and pattern of hearing loss and ask questions such as "When did the hearing loss start?", "Did it get worse over time?" And "Did it happen suddenly or in stages?" Premature hearing loss is one of the most common features of Pendred syndrome; However, this symptom alone does not mean that a child has the condition.

The specialist will use inner ear imaging techniques such as magnetic resonance imaging (MRI) or a computed tomography (CT scan) to look for two features of Pendred syndrome. A trait can be a cochlea with too few turns. The cochlea is the spiral-shaped part of the inner ear that converts sound into electrical signals that are sent to the brain. A healthy cochlea has two and a half turns, but the cochlea of ​​a person with Pendred syndrome may only have one and a half turns. However, not everyone with Pendred syndrome has an abnormal cochlea.

A second feature of Pendred syndrome is an enlarged vestibular aqueduct (see figure). The vestibular aqueduct is a bony canal that runs from the vestibule (part of the inner ear between the cochlea and the semicircular canals) to the inside of the skull. In the vestibular aqueduct is a fluid-filled tube called the endolymphatic canal that ends at the balloon-shaped endolymphatic sac. The endolymphatic canal and sac are usually enlarged as well.

Experts do not recommend testing thyroid hormone levels in children with Pendred syndrome, as levels are usually normal. Some children may be given a "perchlorate washout test," a test that determines if the thyroid is functioning properly. While this test is probably the best test for determining thyroid function in Pendred syndrome, it is not commonly used and has largely been replaced by genetic testing. People who have developed a goiter can be referred to an endocrinologist, a doctor who specializes in glandular disease, to determine whether the goiter is due to Pendred syndrome or some other cause. Goiter is a common feature of Pendred syndrome, but many people who develop a goiter do not have Pendred syndrome. Conversely, many people with Pendred syndrome never develop a goiter.

How Common Is Pendred Syndrome?

The SLC26A4 gene, which causes Pendred syndrome, is responsible for about 5 to 10 percent of hereditary hearing loss. As researchers gain more knowledge about the syndrome and its features, they hope to improve doctors' ability to detect and diagnose the condition.

Can Pendred Syndrome Be Treated?

Treatment options for Pendred syndrome are available. Because the syndrome is inherited and can involve thyroid and balance problems, many specialists may be involved in the treatment, including a primary care physician, an audiologist, an endocrinologist, a clinical geneticist, a clinical geneticist, an ENT specialist and an ENT specialist. speech therapist.

To reduce the likelihood of hearing loss progression, children and adults with Pendred syndrome should avoid contact sports that can lead to head injuries; wear head protection during activities such as cycling and skiing that can lead to head injuries; and avoid situations that could lead to barotrauma (extreme, rapid changes in pressure), such as diving or hyperbaric oxygen treatment.

Pendred syndrome has no cure, but a medical team will work together to encourage informed choices about treatment options. They can also help people prepare for increased hearing loss and other possible long-term consequences of the syndrome.

Children with Pendred syndrome need to start treatment early for communicative skills

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