Usher syndrome

Usher syndrome is a genetic condition#

Usher syndrome is the most common genetic cause of combined vision and hearing impairment, and of deafblindness. People with the condition usually have partial or total hearing loss together with a gradual loss of vision caused by retinitis pigmentosa. Some people also have problems with their balance.

The condition is divided into three broad groups according to the type and severity of symptoms: Type 1, Type 2 and Type 3. Together, Type 1 and Type 2 account for a small proportion of children born with a hearing impairment. There is currently no cure.

Symptoms and signs#

The symptoms of Usher syndrome depend on the type, but generally involve a combination of:

• hearing impairment or deafness
• vision loss caused by retinitis pigmentosa (RP)
• balance problems in some people

Vision loss#

Retinitis pigmentosa is an eye disease that causes a gradual loss of vision over time as the retina deteriorates. At first, a person becomes “night blind” and can no longer see well in dim light. Over time their field of vision narrows until only a central “tunnel” of vision remains.

Balance problems#

Balance can be affected by problems in the inner ear. Our sense of balance relies on information sent to the brain from a series of fluid-filled canals within the ear, set at different angles. When the head moves, the movement of the fluid tells the brain how far, how fast and in what direction the head is moving, relaying the information along the vestibular nerve. The brain also uses signals from receptors in the muscles, joints and skin that sense the movement and position of the body.

Types of Usher syndrome#

Usher syndrome is grouped into Type 1, Type 2 and Type 3, and each type can be further divided into subtypes.

Type 1 (US1)#

• The person is profoundly deaf from birth.
• Speech is affected, and other means of communication such as sign language may be needed.
• Balance can be affected, and children are often late to sit, stand and walk.
• Eye problems vary from person to person but often begin to develop within the first ten years of life.

Type 2 (US2)#

• Moderate hearing loss is experienced in the lower sound frequencies and more severe loss in the higher frequencies.
• Balance may be affected in later years.
• Vision loss, such as blind spots, tends to start in the teenage years and may progress over time.

Type 3 (US3)#

• The person is born with normal, or close to normal, hearing and balance.
• Hearing loss becomes more pronounced with age, with measurable loss usually by puberty.
• Vision loss starts to develop during the teenage years and may progress over time.
• Balance also tends to deteriorate as the person gets older.
• Type 3 is more common in some populations.

What causes Usher syndrome#

Humans have 46 chromosomes arranged in pairs, including two sex chromosomes. Genes are arranged along these strands, and they also come in pairs, with one copy inherited from each parent. The different types of Usher syndrome are caused by changes in different genes, and researchers believe around 15 genes can be involved.

Usher syndrome follows an autosomal recessive inheritance pattern. This means that for a child to develop the condition, they must inherit a changed Usher gene from both parents. If a child inherits only one changed gene, they will not develop the condition but will be a carrier.

Diagnosis#

Tests used to confirm a diagnosis of Usher syndrome can include:

• eye tests to check for retinitis pigmentosa
• hearing tests
• tests to measure balance, such as electronystagmography (ENG)
• genetic testing

Living with Usher syndrome#

There is currently no treatment or cure for Usher syndrome. Care focuses on managing the vision, hearing and balance problems involved.

Managing hearing impairment may involve hearing aids, cochlear implants, adaptive technology, sign language training and other communication skills training.

Balance problems may be managed with vestibular rehabilitation therapy. This is an exercise-based program run by a physiotherapist, which aims to improve balance and coordination in children with Usher syndrome.

Managing vision problems may involve access to low-vision services, learning to use Braille, magnifying aids, adaptive technology, and orientation and mobility training.

Support is also available through community support groups, advocacy organisations and genetic counselling.

Genetic counselling#

If you or your child have been diagnosed with Usher syndrome, or if it runs in your family, it can help to speak to a genetic counsellor. Genetic counsellors are health professionals qualified in both counselling and genetics. As well as providing emotional support, they can help you understand what causes Usher syndrome, how it is inherited, and what a diagnosis means for health, development and plans for the future.

Genetic counsellors are trained to provide information and support that is sensitive to your family circumstances, culture and beliefs. If the condition runs in your family, a counsellor can explain the genetic testing options available to you and to other family members. You may choose to see a genetic counsellor if you are planning a family, to find out your risk of passing on the condition, or to arrange prenatal tests.

Key points#

• Usher syndrome is the most common genetic cause of combined vision and hearing impairment and deafblindness.
• It is divided into three broad groups according to the type and severity of symptoms: Types 1, 2 and 3.
• Symptoms depend on the type but generally include hearing impairment and vision loss caused by retinitis pigmentosa, sometimes with balance problems.
• The different types of Usher syndrome are caused by changes in different genes.
• There is currently no cure, so care focuses on managing the hearing, vision and balance problems involved.

Where to get help#