What is Pendred syndrome?
Pendred syndrome may be a genetic disease that causes early deafness in children. It can also affect the thyroid and sometimes creates problems with balance. The syndrome is known as after Vaughan Pendred, the physician who first described people with the disorder.
Children who are born with Pendred syndrome may begin to lose their hearing at birth or by the time they're three years old. Usually, their hearing will worsen over time. The loss of hearing often happens suddenly, although some individuals will later regain some hearing. Eventually, some children with Pendred syndrome become totally deaf.
Almost all children with Pendred syndrome have bilateral deafness , which suggests deafness in both ears, although one ear may have more deafness than the opposite.
Childhood hearing loss 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 result from environmental causes. Health care professionals use different clues, like when the deafness begins and whether there are anatomical differences within the ears, to assist determine whether a toddler has Pendred syndrome or another sort of progressive deafness.
How does Pendred syndrome affect other parts of the body?
Pendred syndrome can make the thyroid grow larger. An enlarged thyroid gland is called a goiter. The thyroid may be a small, butterfly-shaped gland within the front of the neck, just above the collarbones. The thyroid plays a serious role in how the body uses energy from food. In children, the thyroid is vital for normal growth and development. Children with Pendred syndrome, however, rarely have problems growing and developing properly albeit their thyroid is affected. Their levels of thyroid hormones are usually normal.
People with Pendred syndrome are significantly more likely than the overall population to develop a goiter in their lifetime, although not everyone who has Pendred syndrome gets a goiter. The typical age for a goiter to develop is in adolescence or early adulthood. If a goiter becomes large, there could also be problems with breathing and swallowing. In this case, a health professional should check the goiter and decide whether treatment is necessary. People with Pendred syndrome may have to go to an endocrinologist, who may be a specially trained doctor conversant in diseases and disorders that involve the system, including the thyroid.
Pendred syndrome can also affect the vestibular apparatus, which controls balance. Some people with Pendred syndrome will show vestibular weakness when their balance is tested. However, the brain is extremely good at making up for a weak vestibular apparatus, and most youngsters and adults with Pendred syndrome do not have a drag with their balance or have difficulty doing routine tasks. Some babies with Pendred syndrome may start walking later than other babies, however.
What causes Pendred syndrome?
Pendred syndrome is often caused by changes, or mutations, during a gene called SLC26A4 (formerly referred to as the PDS gene) on chromosome 7. Because it's a recessive trait, a toddler must inherit two mutated SLC26A4 genes—one from each parent—to have Pendred syndrome. Since the child's parents are only carriers of a mutation within the SLC26A4 gene, there are not any health implications for them.
Couples who are concerned that they might pass Pendred syndrome to their children might want to hunt genetic testing. A possible sign that somebody could be a carrier of a mutated SLC26A4 gene may be a case history of early deafness. Another sign may be a loved one who has both a goiter and deafness. However, often there's no case history of Pendred syndrome within the families of youngsters who have the disorder. A mutation within the SLC26A4 gene is often determined by genetic testing of a blood sample.
The decision to possess a genetic test is complicated. Most people talk with a genetic counselor trained to assist them weigh the medical, emotional, and ethical considerations of testing. A genetic counselor may be a health care provider who provides information and support to people (and their families) who have a genetic disease or who are in danger for a genetic disorder.
How common is Pendred syndrome?
The SLC26A4 gene, which causes Pendred syndrome, accounts for about 5 to 10 percent of hereditary deafness. As researchers gain more knowledge about the syndrome and its features, they hope to enhance doctors' ability to detect and diagnose the disorder.
How is Pendred syndrome diagnosed?
An otolaryngologist (a doctor who focuses on diseases of the ear, nose, throat, head, and neck) or a clinical geneticist will consider deafness , internal ear structures, and sometimes the thyroid in 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?”, “Has it worsened over time?”, and “Did it happen suddenly or in stages?” Early deafness is one among the foremost common characteristics of Pendred syndrome; however, this symptom alone doesn’t mean a toddler has the condition.
The specialist will use internal ear imaging techniques like resonance imaging (MRI) or a computerized tomography (CT scan) to seem for 2 characteristics of Pendred syndrome. One characteristic could be a cochlea with too few turns. The cochlea is that the spiral-shaped a part of the internal 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 an individual with Pendred syndrome may have only one-and-a-half turns. Not everyone with Pendred syndrome, however, has an abnormal cochlea.
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