- Huntington chorea
- Huntington's chorea
- Huntington's disease
Your QuestionA friend of mine has been diagnosed with Huntington disease. No one else in his family has this condition. Is it possible that a chemical exposure could have caused it, such as to vinyl chloride?
We have identified the following information that we hope you find helpful. If you still have questions, please contact us.
Questions on this page
- What causes Huntington disease?
- Can people without a family history of Huntington disease still develop the condition?
- Can environmental exposures cause gene expansion like that of the CAG repeat that causes Huntington disease?
- Are there certain chemicals or substances that people with Huntington disease should avoid?
- Who can I contact to learn more about genetic disease and environmental exposure?
- How can I find a genetics professional in my area?
- How can I learn about research involving Huntington disease?
The HTT gene mutation that causes HD involves a DNA segment known as a CAG trinucleotide repeat. This segment is made up of 3 DNA building blocks that repeat multiple times in a row. The CAG segment in a normal HTT gene repeats about 10 to 35 times. In people with HD, it may repeat from 36 to over 120 times. People with 36 to 39 CAG repeats (an intermediate size) may or may not develop HD, while people with 40 or more repeats almost always develop HD.
An increased number of CAG repeats leads to an abnormally long version of the huntingtin protein. The long protein is then cut into smaller, toxic pieces that end up sticking together and accumulating in neurons. This disrupts the function of the neurons, ultimately causing the features of HD.
Freidman JH et al., Monozygotic Twins Discordant for Huntington Disease After 7 Years. Arch Neurol. 2005;62:995-997.
The first article is available in free full text. To obtain a copy of the following article, contact a medical, university, or local library. You can call the National Library of Medicine toll-free at 888-346-3656 to locate libraries in your area that can provide direct access to journals. You can also purchase the article online by clicking on the link above.
Web site: http://www.niehs.nih.gov
Genetics clinics are a source of information for individuals and families regarding genetic conditions, treatment, inheritance, and genetic risks to other family members. More information about genetic consultations is available from Genetics Home Reference. To find a genetics clinic, we recommend that you contact your primary healthcare provider for a referral.
The following online resources can help you find a genetics professional in your community:
- The National Society for Genetic Counselors provides a searchable directory of US and international genetic counseling services.
- The American College of Medical Genetics has a searchable database of US genetics clinics.
- The University of Kansas Medical Center provides a list of US and international genetic centers, clinics, and departments.
- The American Society of Human Genetics maintains a database of its members, which includes individuals who live outside of the United States. Visit the link to obtain a list of the geneticists in your country, some of whom may be researchers that do not provide medical care.
You can also contact the Patient Recruitment and Public Liaison (PRPL) Office at the National Institutes of Health (NIH). We recommend calling the toll-free number listed below to speak with a specialist who can help you determine if you or someone you know is eligible for any clinical trials.
Patient Recruitment and Public Liaison Office
NIH Clinical Center
Bethesda, Maryland 20892-2655
Web site: http://clinicalcenter.nih.gov/
You can find helpful general information on clinical trials at the following ClinicalTrials.gov Web page.
A tutorial about clinical trials that can also help answer your questions can be found at the following link from the National Library of Medicine:
The Huntington Study Group (HSG) is a non-profit group of clinical investigators from medical centers in the United States, Canada, Europe, Australia, New Zealand and South America with experience in the care of patients and families affected by Huntington disease and dedicated to clinical research of this hereditary disorder. The HSG focuses on clinical research, including treatment trials and observational studies aimed at relieving the burden and slowing the progression of Huntington disease. See the Clinical Trials and Observational Studies in Progress for the current HSG trials.
The National Institute of Neurological Disorders and Stroke (NINDS), a part of the National Institutes of Health (NIH), has developed a brochure which presents information about Huntington disease and about current research progress. You can access this brochure online at the following link: http://www.ninds.nih.gov/disorders/huntington/detail_huntington.htm#123783137
The NINDS has sponsored a Huntington Disease Research Roster at the Indiana University Medical Center in Indianapolis. This roster makes research possible by matching scientists with patient and family volunteers. The first DNA bank was established through the roster. Although the gene has already been located, DNA from individuals who have HD is still of great interest to investigators. Participation in the roster and in specific research projects is voluntary and confidential. For more information about the roster and DNA bank, contact:
Indiana University Medical Center
Department of Medical and Molecular Genetics
Medical Research and Library Building
975 W. Walnut Street
Indianapolis, IN 46202-5251
Resources on many charitable or special-fare flights to research and treatment sites and low-cost hospitality accommodations for outpatients and family members, as well as ambulance services, are listed on the Web site of the Office of Rare Diseases (ORD), part of the National Institutes of Health.
- Huntington disease. Genetics Home Reference. June, 2013; http://ghr.nlm.nih.gov/condition/huntington-disease.
- Simon C Warby, Rona K Graham, and Michael R Hayden. Huntington Disease. GeneReviews. December 11, 2014; http://www.ncbi.nlm.nih.gov/books/NBK1305/.