Huntington’s disease is passed from parent to child through a genetic mutation in the huntingtin gene. This mutation is a long sequence of repeated CAG nucleotides. Based on the number of these repeats, doctors can predict whether or not a patient will develop the disease. Patients with 26 or fewer repeats will not develop the disease and neither will their children. Patients with 40 or more repeats will develop the disease, and their children with have a 50/50 chance of inheriting that same mutation. Having between 27 and 39 repeats puts patients in the “gray area.” They may or may not develop the disease. “It’s unclear why some people with reduced penetrance genes develop the symptoms of Huntington’s as early as midlife., while others reach old age with no symptoms. Additional genetic and environmental factors may modify the likelihood that a person develops the disease.” To read more, click here.
