Huntington Diseas is a genetic disorder that affects nerve cells. Symptoms, which normally appear in a persons's 40, include loss of muscal control and brain fuction. The symtoms worsen for 15 years or so before the dieases causes death. It is caused by versions of a single gene on the short arm of chromosome 4. This gene contains a region in which the bases CAG repeat. In people without the disease, there may be about 11 to 34 repeats; if there are more than about 42 in either copy of the gene, Huntington's disease will set in. The more repeats, the earlier the onset.
For example, Huntington disease affects both men and women