Chorea
Huntington's Disease is inherited, with symptoms usually appearing after the age of 30. It is due to a defect in a gene, which causes the development of jerky, uncontrolled movements called chorea. This word comes from the Latin root meaning dance (as in choreographer). The movements are repetitive writhing, twisting, and dance-like, with stiffness and difficulty walking. There are psychiatric symptoms, with early development of dementia, often accompanied by epilepsy. Since the inheritance is transmitted in a dominant mode, one half of the offspring of an affected individual will be affected. Very rarely, in aggressive cases, symptoms appear in late adolescence. There is a blood test available to the offspring of sufferers to see if they carry the affected gene before the development of symptoms, though this should not be undertaken without careful genetic counselling.
There are other conditions which produce involuntary, choreiform, movements in childhood and adolescence, such as SYDENHAM’S CHOREA, or St VITUS’ DANCE, which affects adolescents after throat infections. These movements are gentler, and usually resolve after a few months. WILSON’S DISEASE is a defect in copper metabolism which causes an excess of copper to be deposited in the liver and in parts of the brain, resulting in both abnormal movements and psychiatric symptoms.
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