Huntington’s Disease (HD)

What is HD?

HD is a rare, fatal, genetic disease that causes the breakdown of nerve cells in the brain over time. HD affects a person’s mental, behavioral and physical abilities, including their ability to reason, walk and speak.1

Who is affected by HD?

In the U.S., there are approximately 30,000 people with symptomatic HD and more than 200,000 people at risk of inheriting the disease.1

HD is caused by a single defective gene called huntingtin (HTT). The mutation in the HTT gene leads to the production of a toxic mutant huntingtin protein.2 HD is an autosomal dominant disorder, meaning that every child of a parent with HD has a 50% chance of inheriting the faulty gene and developing the disease.3

What are the symptoms of HD?

There is a wide range of signs and symptoms of HD and they can vary greatly from person to person. Symptoms can include:1,3

  • Depression and changes in behavior and mood
  • Decline in thinking and reasoning skills
  • Uncontrolled movements and impaired walking
  • Difficulty with speech and swallowing
  • Weight loss

Most people with HD develop signs and symptoms between the ages of 30 to 50 years. HD is a progressive disease, so a person's symptoms gradually worsen over 10 to 25 years, ultimately leading to death.1

Living with HD

There are several organizations that support people with HD and their families through education, advocacy, services and research, including Huntington's Disease Society of America (HDSA), Help 4 HD International and The Huntington Study Group (HSG).

There are treatments available to help manage the symptoms of HD. However, there are currently no disease-modifying treatments to help prevent, slow or stop the progression of the disease. Scientists around the world are researching potential new treatment options.

Learn about Genentech’s clinical trials in Huntington’s Disease here, or contact the Clinical Trial Information Support Line at 1-888-662-6728.


1 Huntington's Disease Society of America (HDSA). What is HD. https://hdsa.org/what-is-hd/. Accessed December 6, 2018.
2 National Institute of Health (NIH). Huntington disease. https://ghr.nlm.nih.gov/condition/huntington-disease#inheritance. Accessed December 6, 2018.
3 Mayo Clinic. Huntington's disease. https://www.mayoclinic.org/diseases-conditions/huntingtons-disease/symptoms-causes/syc-20356117. Accessed December 6, 2018.