HUNTINGTON'S DISEASE

What is it?

Huntington's disease is a hereditary disorder of the central nervous system. Symptoms typically appear in adult life between the ages of 30 and 50. It is most often characterised by chronic progressive chorea and dementia without remissions.

Who gets it?

It is estimated that 30,000 persons have Huntington's disease nationwide. Another 150,000 are at a 50 percent risk of inheriting the disease from an affected parent. The age of onset can range from age two to over age 80.

Huntington's disease is caused by a "genetic stutter" -a stretch of DNA repeated over and over at one end of a gene on Chromosome four.

What are the symptoms?

An individual with Huntington's disease often has problems in three areas: control of bodily movements, intellectual functioning and emotional control. The intensity and number of the above symptoms, however, varies with each Huntington's disease patient.

Chorea--quick, jerking, uncontrollable movements of the limbs, trunk and face are the most obvious symptoms. The patient's gait is often mistaken for that of a person who is drunk.

Poor short-term memory and judgement--Although most patients continue to recognise their caregivers and can give feedback about their condition and care, the Huntington's disease patient suffers declining mental skills as the disease progresses.

Depression, irritability and apathy can be noted before and after the onset of chorea in a percentage of the Huntington's disease population. Some patients may exhibit schizophrenic-like behaviour.

What tests will the Doctor want to do?

If there is a positive family history of Huntington's disease, the presence of an extrapyramidal movement disorder (when nerve impulses are not properly transferred to the muscles) is usually enough to confirm a diagnosis. Conventional neurological examinations and the presence of depression and other psychological disturbances are not enough to provide an accurate diagnosis.

In 1993, after a ten-year search, scientists announced the discovery of the gene which causes Huntington's disease. This breakthrough has led to the development of a direct gene test for HD which can be used to predict the onset of Huntington's before symptoms develop. This test is more accurate and less complicated than the genetic marker test which has been in place since 1986.

What is the treatment?

There is no cure for Huntington's disease. Medication can help the involuntary movements and emotional disorders for some Huntington's disease patients.

Because of the strong emotional impact of the diagnosis and the stress of living with the knowledge that the children in the family may be at risk, family counselling and/or participation in support groups can be very helpful.