Huntington's disease

Huntington's disease (HD) is a degenerative brain disorder for which at present there is no cure. Typically, the disease begins in midlife, between the ages of 30 and 45, although onset may occur at any age. Early symptoms can be mild enough to go unnoticed at first and may include depression, mood swings, forgetfulness, clumsiness, twitching, and lack of coordination. Advanced symptoms are: personality changes, unsteady gait, involuntary movements; slurred speech; impaired judgement; difficulty in swallowing; and intoxicated appearance. As the disease progresses, usually over a 10 to 15 year period, the severity of symptoms increases. Concentration and short-term memory are diminished and involuntary movements become more pronounced. Walking and everyday activities become difficult, and speech and swallowing abilities deteriorate.

Huntington's chorea is named after the American physician Dr. George Huntington, whose historic description of "hereditary chorea" appeared in 1872. Chorea (from the Greek word for 'dance') is a reference to the ceaseless movements of the head, trunk and limbs which are often characteristic of the disease. The gene that is responsible for the disease was identified in 1993.

An estimated 30,000 Americans have Huntington's disease. Males and females are affected equally and HD crosses all racial and ethnic boundaries. A further 150,000 have a 50-50 chance of inheriting the disease from an affected parent and are said to be 'at risk.' Those who do not inherit HD cannot pass it on to their children and the chain of inheritance is broken.