Huntington's Disease

Huntington’s disease (HD) is a genetic, autosomal dominant disorder in which there is degeneration of parts of the brain, including the basal ganglia and cerebral cortex. It has a population frequency of about 10/100,000. Males and females are affected equally. The two clinical hallmarks of the disease are chorea and behavioural disturbance. The illness may begin with either or both of these symptoms predominating. The average age of onset is between 30-45 years and life expectancy is approximately 15-20 years, but there is a wide range in age of onset – from childhood to greater than 70 years. The chorea begins as subtle fidgeting that may be unrecognisable by the patient and family. However, the movement disorder is usually slowly progressive and eventually may become disabling. There are frequent, irregular, sudden jerks and movements of any of the limbs or trunk. Grimacing, grunting, and poor articulation of speech may be prominent. The gait is disjointed and poorly co-ordinated and has a so-called dancing (choreic) quality. Memory is frequently not impaired until late in the disease, but attention, judgement, and executive functions may be seriously deficient at an early age. Depression, apathy, social withdrawal, irritability, and intermittent disinhibition are common.

HD is transmitted as an autosomal dominant gene, which means that 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 one child inherits the gene has no bearing on whether others will or will not inherit the gene.

The social and economic consequences of living with HD families can be devastating. This is primarily because of the severe impairment that HD causes and its pattern of inheritance as it passes from one generation to the next. Living at risk, whether you are a child or an adult, can cause profound stress for family members. It is possible for several members from different generations to be affected at the same time. The characteristic features of the disease include increasing physical, emotional and cognitive impairment. Eventually an affected person will need help with more and more aspects of his or her life and ultimately it is likely he or she will become totally dependent on the help of others.

The rate of disease progression and the age of onset vary from person to person. A genetic test, coupled with a complete medical history and neurological and laboratory tests, help physician's 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.

Scottish Huntington's Association