Usher Syndrome

Usher syndrome is an inherited disorder that involves loss of both hearing and vision. (Read about "The Ear & Hearing" "The Eye") It is the most common cause of deaf-blindness and affects about 10-15 thousand people in the U.S., according to the Foundation Fighting Blindness (FFB).

Usher syndrome is characterized by two major symptoms:

• a serious hearing impairment usually present at birth or soon thereafter
• an eye disorder called retinitis pigmentosa (RP) that causes progressive loss of vision through degeneration of the retina, the light-sensitive tissue at the back of the eye that is essential for vision (Read about "Retinitis Pigmentosa")

There is no way to prevent Usher syndrome. It is an inherited genetic disease a person is born with. (Read about "Genetics") It is not caused by injury or infection. (Read about "Microorganisms") The syndrome is passed from parents to their child through genes. Usher syndrome is inherited as an autosomal recessive trait. This means a child must inherit two copies of the Usher syndrome gene, one from each parent in order to develop the disorder. A child who inherits only one copy of the gene from one parent will be a carrier, but will not develop symptoms.

Types of Usher syndrome

There are three known types of Usher syndrome, type I, type II and type III, sometimes referred to as USH1, USH2 and USH3.

Here are the characteristics of each according to the National Institute on Deafness and Other Communication Disorders (NIDCD).

People with Usher syndrome Type I:

• are born nearly or completely deaf
• have serious balance problems
• begin having vision problems in early adolescence

People with Usher syndrome Type II:

• are born with moderate to severe hearing impairment
• have normal balance
• begin having vision problems shortly after adolescence

People with Usher syndrome Type III:

• are born with normal hearing and balance
• begin having hearing and vision problems in adolescence

Usher Types I and II are the most common, accounting for 90-95 percent of all cases, according to NIDCD. The remaining cases are made up of the rare Usher Type III.

While hearing impairment is present from birth in types I and II, in type III it is progressive and worsens over time. The rate of deterioration varies among individuals, even within the same family. There is presently no way to restore normal hearing and the hearing loss cannot be corrected with middle ear surgery. FFB says some patients with severe hearing impairment may benefit from cochlear implants and others who retain some residual hearing may benefit from hearing aids.

The vision problems caused by retinitis pigmentosa begin the same in all three Usher types. Night blindness and loss of peripheral vision occur first as the retina begins to degenerate. In Usher type I, the symptoms appear earlier and progress more rapidly. In types II and III, the symptoms begin later and progress more slowly. All eventually deteriorate into blindness. While it is not possible to stop the degeneration of the retina, FFB says a specific dose of vitamin A (Read about "Vitamins & Minerals") has been found to slow down the progression of RP in some individuals with Usher syndrome type II. You can ask your doctor for more information. In addition, because unprotected exposure to sunlight may actually accelerate vision loss (Read about "Eyes & Sun"), FFB recommends wearing sunglasses and hats when outdoors.

Diagnosis of Usher syndrome

Hearing loss and retinitis pigmentosa are rarely found in combination, according to NIDCD. Therefore, most people with both disorders probably have Usher syndrome. However, Usher syndrome is a genetic disorder and there is not yet a common genetic test for it. As a result, diagnosis is still based on testing, according to the National Eye Institute (NEI), a division of the National Institutes of Health.

Doctors diagnose Usher syndrome with a series of hearing and visual tests including examination of the retina and an electroretinogram (ERG) to detect RP. (Read about "Eye Exams") Doctors also perform balance tests.

Treatment for Usher syndrome

Currently, there is no cure for Usher Syndrome and no way to minimize its symptoms. There is no way to halt the deterioration of the retina caused by RP and there is no way to restore normal hearing. Right now, the most effective treatment is to provide special educational and training programs to help individuals deal with the difficulties of hearing and vision loss.

According to NIDCD, the nature of these programs will depend on the severity of the hearing and vision loss as well as the age and abilities of the individuals. The programs may include:

• hearing aids, assistive listening devices or cochlear implants
• auditory training
• Braille instruction
• low-vision services
• communication services
• orientation and mobility training
• independent living training
• adjustment and career counseling

Research and the future

One possible future treatment for Usher syndrome would help recover vision loss. FFB says scientists are presently working on developing high-tech intraocular implants to help restore vision.

In addition, genetic research is being done in relation to Usher syndrome. As noted above, there is not a common genetic test for Usher syndrome right now. Presently, genetic testing is done only for research purposes. One reason for this, according to NEI, is that more than one gene causes Usher syndrome. So far, scientists have mapped 10 genes for different types of Usher and there are still more to find. Once a good genetic test is developed, it will help doctors diagnose the syndrome earlier and identify carriers to help determine the risks of future offspring being affected.