What is Huntington Disease?

A brief description :

Huntington disease (HD) is an inherited brain disorder. It was named after the doctor who first described it in 1872, George Huntington, and it used to be called Huntington�s chorea.

HD causes cells in specific parts of the brain to die: the caudate, the putamen, and, as the disease progresses, the cerebral cortex. The caudate and putamen have connections to many other areas of the brain, and help to control body movement, emotions, thinking, behaviour and perception of the world.

As the cells die,  people with Huntington�s become less able to control movements, recall recent events, make decisions, and control emotions. The disease leads to incapacitation and, eventually death.

Who gets it?

Approximately one in every 10,000 Canadians has HD, and approximately five in every 10,000 are at risk of developing the disease.

HD is a genetic disorder, caused by a faulty gene on chromosome 4. The HD gene is dominant, which means that each child of a parent with HD has a 50% chance of inheriting the disease and is said to be �at risk�. Males and females have the same risk of inheriting the disease.

Huntington�s occurs in all races, but it is most prevalent in people of European ancestry.

Primarily Huntington�s affects adults. Symptoms usually appear between the ages of 30 and 45, but the disease can firs appear in children as young as five or in adults in their 70s.

What causes it?

It�s not clear how the abnormal gene causes the disease. Since the discovery of the gene in 1993, scientists have been working hard to discover the biochemical processes that cause the brain cells to die.

So far, we have learned that the HD Gene produces a protein called �huntingtin�, In people with HD, this protein gets cut into one short piece and one longer piece. The shorter pieces stick together to form a �protein ball�.

Scientists are currently investigating whether it is the breakage of the protein, the formation of protein balls, or some other process that leads to cell death. They are also trying to understand why only certain brain cells die.

What are the symptoms?

There are three main types of symptoms in Huntington disease:

• physical symptoms, including involuntary movements and clumsiness
• emotional symptoms, including depression, irritability and obsessiveness
• cognitive symptoms, including loss of ability to recall information, loss of attention and difficulty with decision making.

There is a lot of variation in symptoms, and not every person will have all the symptoms to the same degree. For example, some people with HD may have a lot of difficulty with involuntary movements, while others may have fewer physical symptoms but many emotional or cognitive difficulties. Symptoms also vary with each stage of the disease.

How is it diagnosed?

Huntington�s is usually diagnosed using neurological and psychological tests. Sometimes doctors use brain scans to see whether the caudate and putamen are working properly, or they use the genetic test to confirm diagnosis.

For more information on Huntington Disease, contact our National Office of the Huntington Society of Canada,

151 Frederick Street, Suite 400

Kitchener, Ontario, N2H 2M2

1-800-998-7398 email: [email protected]

National website: www.hsc-ca.org

Huntington Disease Resource Centre

UBC Hospital

S179-2211 Wesbrook Mall,

Vancouver, B.C.

V6T 2B5

Susan Tolley, Director

604-822-7195

Vancouver B.C. Chapter, Huntington Society of Canada

Leave a message at 604-682-3269 Extension 6159