Usher Syndrome

What is Usher Syndrome?

Usher syndrome is an inherited condition characterized by progressive vision and hearing loss. Balance may also be affected. Symptoms and disease progression vary from person to person.

The vision loss is due to retinitis pigmentosa (RP), a degenerative condition of the retina, and usually appears during childhood, adolescence or early adulthood.  The retina is a thin layer of tissue lining the back of the eye composed of light-sensing photoreceptor cells. These cells — also known as rods and cones — are responsible for converting light into electrical signals that the brain interprets as vision.

Hearing loss in Usher syndrome occurs, because the gene mutations affecting the retina also affect the cochlea, a sound-transmitting structure of the inner ear.

Researchers estimate that as many as 25,000 people in the U.S. have Usher syndrome. Worldwide, it is the leading cause of combined deafness and blindness. About 30 percent of people with RP report some degree of hearing loss, and about half of them are diagnosed with Usher syndrome.

Symptoms

There are three general categories of Usher syndrome. People with Usher syndrome type 1 (USH1) are usually born with severe hearing loss and experience problems with balance. The first signs of RP — night blindness and loss of peripheral vision — usually appear in early adolescence.

In Usher syndrome type 2 (USH2), newborns have moderate to severe hearing impairment. Symptoms of RP typically start shortly after adolescence. Visual problems progress less rapidly than in Usher type 1, and hearing loss usually remains stable.

A rarer third type of Usher syndrome (USH3) was documented in 1995. Children with USH3 are usually born with good or only mild impairment of hearing. Their hearing and vision loss are progressive, starting around puberty. Balance may also be affected.

Usher syndrome is further subdivided into types, based on the mutated gene causing the disease. For example, people with Usher syndrome type 1B have mutations in the MYO7A gene.

The most common genes associated with Usher syndrome are CLRN1, MYO7A, PCDH15, and USH2A.

Inheritance

Usher syndrome is passed from parents to their offspring through an autosomal recessive inheritance pattern. In autosomal recessive disease, both parents carry one copy of the mutated gene and one normal copy, but have no symptoms themselves. They are therefore referred to as unaffected carriers. Each of their children has a 25 percent chance of being affected by inheriting a mutated copy from each parent. If the child inherits one mutated copy from one parent, they will be an unaffected carrier.

Living with Usher syndrome

There are many services and accommodative and assistive resources available to people and families with Usher syndrome. Visit the Foundation’s Low Vision Resources page to learn about many of these resources. A low vision specialist can help recommend the resources that are right for you.

Genetic Testing

Genetic testing is available to help people definitively diagnose their condition and the risk of other family members or future offspring being affected. A genetic diagnosis can also help a person qualify for a clinical trial. Genetic counselors are excellent resources for discussing inheritability, family planning, genetic testing, and other related issues.

Research and Clinical trials

For more information on research and clinical trials for Usher syndrome, refer to the Foundation publication Usher Syndrome: Research Advances.

View a list of current clinical trials, many made possible by Foundation support.

Usher Syndrome page at www.ClinicalTrials.gov.

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