Usher syndrome

What is Usher syndrome?

Usher syndrome is characterised by hearing loss, visual problems and problems with balance. The visual problems are due to a condition called retinitis pigmentosa, in which the retina slowly degenerates and gradually loses its ability to send images to the brain, resulting in a progressive loss in vision.

There are at least three types of Usher syndrome. Type 1 (USH1) and Type 2 (USH2) are the most common and account for up to 95 per cent of children with the condition.

• Type 1: the child is profoundly deaf from birth. Hearing aids are usually of little help and sign language is used for communication. There are also severe problems with balance, so a child may be slow to sit unsupported and is often late learning to walk. Visual problems have usually started to develop by the age of ten - difficulty seeing in reduced light at night is often the first symptom. Deterioration in vision may be rapid and lead to complete blindness.

• Type 2: the child usually has moderate to severe hearing problems from birth. Balance, however, is normal. Hearing aids may allow the child to cope within mainstream school and most can use speech and lip-reading for communication. Vision deteriorates more slowly than with Type 1, and problems may not begin until early adult life.

• Type 3: hearing and sight are normal at birth, but both deteriorate at a rate that varies from person to person. Problems are usually evident by late teens, and by the time most people with Type 3 have reached their 40s they're blind and have complete hearing loss.

Causes and risk factors

Between three and six per cent of all children with hearing difficulties have Usher syndrome. It affects about one in every 25,000 babies born in developed countries.

Usher syndrome is a genetic condition, inherited in an autosomal recessive fashion. This means a child will only develop the condition if they inherit two genes for it, one from each parent.

In most cases, each parent only carries one Usher syndrome gene, so they don't have the condition and are often unaware they're a carrier.

A number of different genes have been found that may contribute to Usher syndrome. These normally help the retina in the eye and the cochlea in the inner ear to work properly. In children with the condition, one or more of these genes is faulty.

Treatment and recovery

There's no cure for Usher syndrome, but the earlier it's diagnosed, the more can be done to help children lead as normal a life as possible.

Hearing aids and other communication technology, cochlear implants and specialised support at school may all help the child adjust to their disabilities.

Counselling may be helpful, particularly regarding future careers. Genetic counselling is important for the individual's future plans for a family and for the rest of the family, too.

Gene therapy looks increasingly promising as a treatment for retinitis pigmentosa, but it's still many years away.