The HTT gene provides instructions for making a protein called huntingtin. Although the exact function of this protein is unknown, it appears to play an important role in nerve cells (neurons) in the brain and is essential for normal development before birth.

What is the DNA abnormality associated with Huntington's disease?

HD is caused by a genetic defect on chromosome 4. The defect causes a part of DNA to occur many more times than it is supposed to. This defect is called a CAG repeat. Normally, this section of DNA is repeated 10 to 28 times. But in persons with HD, it is repeated 36 to 120 times.

What is the scientific name for Huntington's disease?

Huntington’s disease (HD), also known as Huntington’s chorea, is a neurodegenerative disease that is mostly inherited. The earliest symptoms are often subtle problems with mood or mental abilities.