Huntington's disease causes

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

• 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 35 times. But in persons with Huntington’s disease, it is repeated 36 to 120 times.

• As the gene is passed on from one generation to the next, the number of repeats called a CAG repeat expansion 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, it becomes evident at younger and younger ages.

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