Definition for Huntington's disease
From Biology Forums Dictionary
Huntington's disease is a disorder passed down through families in which nerve cells in certain parts of the brain waste away, or degenerate.
Causes, incidence, and risk factors
Huntington's disease is caused by a genetic defect on chromosome 4. The defect causes a part of DNA, called a CAG repeat, to occur many more times than it is supposed to. Normally, this section of DNA is repeated 10 to 28 times. But in persons with Huntington's disease, it is repeated 36 to 120 times.
As the gene is passed down through families, the number of repeats tend to get larger. The larger the number of repeats, the greater your chance of developing symptoms at an earlier age. Therefore, as the disease is passed along in families, symptoms develop at younger and younger ages.
