Huntington's disease (HD), also known as Huntington disease and previously as Huntington's chorea and chorea maior, is a rare inherited neurological disorder affecting up to almost 8 people per 100,000. It affects 1 out of 20,000 people of Western European descent and 1 out of one million in people of Asian and African descent. It takes its name from the New York physician George Huntington who described it precisely in 1872 in his first medical paper. HD has been heavily researched in the last few decades and it was one of the first inherited genetic disorders for which an accurate test could be performed. Huntington's disease is caused by a trinucleotide repeat expansion in the Huntingtin (Htt) gene and is one of several polyglutamine (or PolyQ) diseases. This expansion produces an altered form of the Htt protein, mutant Huntingtin (mHtt), which results in neuronal cell death in select areas of the brain. Huntington's disease is a terminal illness.
Huntington's disease's most obvious symptoms are abnormal body movements called chorea and a lack of coordination, but it also affects a number of mental abilities and some aspects of personality. These physical symptoms commonly become noticeable in a person's fortiescitation needed], but can occur at any age. If the age of onset is below 20 years then it is known as Juvenile HD. As there is currently no proven cure, symptoms are managed with various medications and care methods.