Huntington disease

What is Huntington disease?

Huntington disease (HD) results from genetically programmed degeneration of brain cells, called neurons, in certain areas of the brain. This degeneration causes uncontrolled movements, loss of intellectual abilities, and emotional disturbance.

What causes it?

HD is a familial disease, passed from parent to child through a mutation in the normal gene. Each child of an HD parent has a 50-50 chance of inheriting the HD gene. If a child does not inherit the HD gene, he or she will not develop the disease and cannot pass it to subsequent generations. A person who inherits the HD gene will sooner or later develop the disease. Whether or not one child inherits the gene has no bearing on whether others will or will not inherit the gene.

What are the symptoms?

Some early symptoms of HD are:

• Mood swings
• Depression
• Irritability
• Trouble driving
• Difficulty learning new things, remembering facts, or making decisions.

As the disease progresses, concentration on intellectual tasks becomes increasingly difficult. The patient may have difficulty feeding himself or herself and swallowing. He or she may have problems with uncontrolled body movements and difficulty walking. The rate of disease progression and the age of onset vary from person to person.

How is it diagnosed?

A genetic test, coupled with a complete medical history and neurological and laboratory tests, help physicians diagnose HD. Presymptomatic testing is available for individuals who are at risk for carrying the HD gene. In 1 to 3 percent of individuals with HD, no family history of HD can be found.

How is it treated?

Physicians prescribe a number of medications to help control emotional and movement problems associated with HD. Most drugs used to treat the symptoms of HD have side effects such as fatigue, restlessness, or hyper-excitability. It is extremely important for people with HD to maintain physical fitness as much as possible, as individuals who exercise and keep active tend to do better than those who do not. Treatment may also include psychotherapy, speech therapy and nutritional therapy.

What is the prognosis?

At this time, there is no way to stop or reverse the course of HD. Now that the HD gene has been located, investigators are continuing to study the HD gene with an eye toward understanding how it causes disease in the human body.