When someone has Huntington's disease, part of the DNA sequence:
(CAG: Cytosine — Adenine — Guanine) repeats more times than normal.
It is important to understand that everyone on the planet is born with the Huntingtin gene - CAG repeat. The healthy gene repeat averages around 17, however, a person's CAG repeat can range from less than 10 to more than 120. There are two forms of this disease: Adult on-set Huntington's disease, and Juvenile Huntington's disease. Please review the resources on this page for more information about CAG.
More about CAG!
What is Huntington's and
Juvenile Huntington's disease?
National Institute of General Medical Sciences National Institutes of Health