What is usher syndrome

Usher syndrome is inherited as an autosomal recessive disorder. A person with one abnormal Usher gene does not have the disorder but is a carrier who has a 50 percent chance of passing on the abnormal gene to each child. When two carriers with the same mutated Usher syndrome gene have a child together, each birth has a:. There are three types of Usher syndrome. In the United States, types 1 and 2 are the most common.

Together, they account for up to 95 percent of Usher syndrome cases. Type 1: Children with type 1 Usher syndrome have profound hearing loss or deafness at birth and have severe balance problems. Many obtain little or no benefit from hearing aids but may be candidates for a cochlear implant—an electronic device that can provide a sense of sound to people with severe hearing loss or deafness.

Intervention should begin promptly, when the brain is most receptive to learning language, whether spoken or signed. Balance problems associated with type 1 Usher syndrome delay sitting up without support.

Walking rarely occurs prior to 18 months. Vision problems with type 1 Usher syndrome usually begin before age 10, starting with difficulty seeing at night and progressing to severe vision loss over several decades. Type 2: Children with type 2 Usher syndrome are born with moderate to severe hearing loss but normal balance. Although the severity of hearing loss varies, most children with type 2 Usher syndrome can communicate orally and benefit from hearing aids.

RP is usually diagnosed during late adolescence in people with type 2 Usher syndrome. Type 3: Children with type 3 Usher syndrome have normal hearing at birth. Most have normal to near-normal balance, but some develop balance problems with age.

Decline in hearing and vision varies. Children with type 3 Usher syndrome often develop hearing loss by adolescence, requiring hearing aids by mid-to-late adulthood.

Night blindness also usually begins during adolescence. Blind spots appear by the late teens to early twenties. Legal blindness often occurs by midlife. Varies in severity and age of onset; night vision problems often begin in teens and progress to severe vision loss by midlife. Early diagnosis is important, as it improves treatment success. An eye care specialist can use dilating drops to examine the retina for signs of RP.

Visual field testing measures peripheral vision. Optical coherence tomography may be helpful to assess for macular cystic changes. Videonystagmography [vi-de-o-nigh-stag-MAH-gra-fee] measures involuntary eye movements that could signify a balance problem. Audiology testing determines hearing sensitivity at a range of frequencies. Genetic testing may help in diagnosing Usher syndrome. Hearing: Children with Usher syndrome are born with or develop hearing loss.

Balance: Balance is achieved and maintained through input from your eyes, the vestibular organs in the inner ear and the sensory systems of the body, such as the skin, muscles, and joints. Individuals with certain types of Usher syndrome experience severe balance issues due to vestibular dysfunction.

Types: There are three clinical types of Usher syndrome: type 1 , type 2 and type 3 , which are distinguished by the severity and age when the signs and symptoms appear. There are at least eleven different subtypes of Usher syndrome, as determined by the genes that are involved. There are six different genes that cause Usher type 1, three that cause Usher type 2, and two that cause Usher type 3. One cannot determine the genetic type by clinical testing; DNA testing is the only reliable way of determining the true genetic type.

For more information, visit our Frequent Questions page. Unlike the other forms of Usher syndrome, type II is not associated with vestibular abnormalities that cause difficulties with balance. People with Usher syndrome type III experience hearing loss and vision loss beginning somewhat later in life.

Unlike the other forms of Usher syndrome, type III is usually associated with normal hearing at birth.

Hearing loss typically begins during late childhood or adolescence, after the development of speech, and becomes more severe over time. By middle age, most affected individuals have profound hearing loss. Vision loss caused by retinitis pigmentosa also develops in late childhood or adolescence. Some people with Usher syndrome type III develop vestibular abnormalities that cause problems with balance.

Usher syndrome affects around 4 to 17 in , people. Types I and II are the most common forms of Usher syndrome in most countries. Certain genetic mutations resulting in type 1 Usher syndrome are more common among people of Ashkenazi eastern and central European Jewish or French Acadian heritage than in the general population.

Type III represents only about 2 percent of all Usher syndrome cases overall. However, type III occurs more frequently in the Finnish population, where it accounts for about 40 percent of cases, and among people of Ashkenazi Jewish heritage. Usher syndrome can be caused by mutations in several different genes. Mutations in at least six genes can cause Usher syndrome type I. The genes associated with Usher syndrome provide instructions for making proteins involved in normal hearing, balance, and vision.

In the inner ear, these proteins are involved in the development and function of specialized cells called hair cells, which help to transmit sound and signals from the inner ear to the brain. In the retina , the proteins contribute to the maintenance of light-sensing cells called rod photoreceptors which provide vision in low light and cone photoreceptors which provide color vision and vision in bright light.

For some of the proteins related to Usher syndrome, their exact role in hearing, balance, and vision is unknown. Most of the gene mutations responsible for Usher syndrome lead to a loss of hair cells in the inner ear and a gradual loss of rods and cones in the retina. Degeneration of these sensory cells causes the hearing loss, balance problems, and vision loss that occur with Usher syndrome.

In some people with Usher syndrome, the genetic cause of the condition has not been identified. Researchers suspect that several additional genes are probably associated with this disorder. All of the types of Usher syndrome are inherited in an autosomal recessive pattern , which means both copies of a gene in each cell have a mutation.