Health Dictionary
Reliable, easy-to-read patient information on common medical conditions — written in plain language, free of jargon, and grounded in current evidence. Browse the most frequent diagnoses, understand what they mean for everyday life, and learn which steps and questions help you have a focused conversation with your doctor.
Huntington's disease causes
Introduction
Overview
Overview
Causes
Causes
- 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.
References
References
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]