Two Genetic Disorders that Can Cause Hearing Loss in Children
There are two genetic disorders that can cause hearing loss in children; Pendred Syndrome and Usher Syndrome. Both are genetic and cause hearing loss at different rates and at different ages, although always during childhood. The syndromes may also adversely impact balance, vision and the thyroid. Early diagnosis and testing can lead to early support for children and the teaching of communication strategies. Here are the facts about Pendred and Usher Syndromes.
Pendred Syndrome is a genetic disorder that causes children to lose their hearing either at birth or before the age of three. Children who are born hearing will lose their hearing over time and some will become totally deaf. In some cases, children lose their hearing suddenly and later regain some of it. However, nearly all children with Pendred syndrome experience some degree of hearing loss in both ears.
Pendred Syndrome is genetic and children inherit it from their parents. It is a recessive trait which means that a child has to inherit the mutated gene from both parents in order to have the syndrome. Although it is genetic, the National Institute on Deafness and Other Communication Disorders1 estimates that is the cause of only 50 to 60 percent of the cases. It is believed that another 40 to 50 percent of Pendred Syndrome cases are caused by factors in the environment.
Audiologists and other health care experts diagnose Pendred Syndrome after considering many different factors including the anatomy of the ears, the level of hearing loss, and the age when the hearing loss began. An MRI or CT scan may be used to see the anatomy of the ear to determine if there are defects. Because the syndrome can affect the thyroid gland and may also cause balance issues, doctors also take these factors into account when reaching a diagnosis.
Two common indications of Pendred Syndrome in the ear are:
- The cochlea – this is the part of the ear that turns sounds into signals and then sends them to the brain. A defect would manifest if there were only 1 ½ turns in its construction instead of 2 ½ turns
- The vestibular aqueduct – this is the canal that runs from the inner ear to the inside of the skull. If it is enlarged, it could be a cause of Pendred Syndrome
Pendred Syndrome cannot be cured but children with it can be taught communication strategies to cope with the hearing loss. The NIDCD recommends that children with Pendred Syndrome be taught sign language at an early age and depending upon the extent of the hearing loss, be given hearing aids and be considered for a cochlear transplant. Other specialists should be involved in the child’s care to address treatments for thyroid and balance issues.
Usher Syndrome is a genetic disorder that causes hearing loss and vision loss due to retinitis pigmentosa, a condition that degenerates the retina. According to the NIDCD2, approximately 3 to 4 percent of children with hearing loss have Usher Syndrome. The gene that causes Usher Syndrome is a recessive gene and the child must inherit it from both parents in order to have the syndrome.
There are three types of Usher Syndrome:
- Type 1: Children are born profoundly deaf. They have balance problems that usually slow their ability to walk and sit independently. Vision problems may develop in the early years of childhood and progress to blindness.
- Type 2: Children are born with moderate to severe hearing loss. Hearing aids are usually an effective treatment. Balance is not affected and vision problems may not emerge until the teen years.
- Type 3: Children are born with normal hearing. Hearing loss begins eventually but sometimes not until the teen years. Balance is sometimes affected in the later years of childhood. Vision loss slowly progresses and the person may be legally blind by adulthood.
Usher Syndrome is diagnosed by assessing vision, hearing and balance. An audiology test will determine the level of hearing loss at various frequencies. The earlier the syndrome is diagnosed the better it is for the child and his or her parents. Learning special communication skills such as sign language is essential. Whenever possible it should begin before total hearing or vision loss occurs. Hearing aids can be readily fitted for even the smallest children and can be adjusted as hearing loss progresses. Some children may qualify for cochlear implants.
The impact of these syndromes can seem catastrophic. However, early diagnosis by audiologists and a team of trained professionals can facilitate hearing support at the youngest ages. Hearing aids, cochlear implants, assistive devices and sign language, along with other types of support, can help the child participate fully in daily living and tremendously improve quality of life.