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.
by natolia134 November 03, 2009