Huntington's Disease Genetic Test

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Huntington's Disease Genetic Test

What is Huntington's Disease?

Huntington's disease is a rare condition that causes parts of the brain to break down, or degenerate. It is also called Huntington's chorea. The disease causes rapid, jerky body movements and the loss of normal mental abilities (dementia). Huntington's disease can cause personality changes, behaviour problems, and memory loss. Symptoms usually develop after age 40. There is no known cure. But treatment with medicines may help control the involuntary movements and behaviour changes.

Huntington's disease is caused by a changed, or mutated, gene. If you have a parent with the disease, you have a 50% chance of getting the changed gene and the disease. But there is no way to know when you will develop Huntington's disease. Some people may pass on the changed gene to a child before knowing that they have the changed gene.

A blood test can show whether you have the changed gene. You may want to have genetic counselling if you are thinking of having the test. Genetic counsellors are experts who can explain what the test means, tell you the benefits and risks of the test, and answer your questions. But you make the decision about whether to have the test.

What Is the Test?

You give a blood sample, which is screened for the gene change. As part of the test, a close family member—preferably a parent—also may have to give a blood sample. That person's DNA is studied to look for the disease. Testing a family member also may be important in case your family's DNA is unusual in some way that might affect the test result.

Is the Test Accurate?

Although this test is highly reliable, no test is 100% accurate. Also, if you test positive, the test cannot tell you when you will develop Huntington's disease or how quickly the disease will advance.

Should I Be Tested?

The decision to take the test for Huntington's disease is personal. You may have emotional, financial, and family reasons for taking or not taking the test.

You might choose to be tested because:

  • You want to know whether you will get the disease so you can prepare yourself and your family if your test is positive. You might choose, for example, to set up financial arrangements in a certain way or change other life plans.
  • You want to know because the results will affect whether you marry or have children.
  • You think the anxiety of not knowing whether you will get the disease is worse than the certainty of knowing that you will get it.
  • Your provincial health plan or private health insurance will pay for all or most of the test. Or, you can afford to pay for the test yourself.

Why Would I Not Be Tested?

You might choose not to be tested because:

  • News of a positive result (meaning you have the changed gene) would be devastating. You prefer to live without knowing that you will some day get Huntington's disease.
  • You are concerned about how the results would affect your relationships. If you test negative (you do not have the changed gene), you may feel guilty if your brother, sister, or child tests positive. Or you may feel angry if you test positive and your relatives do not.
  • The test is expensive, and you know your provincial health plan or private insurance would not pay for it.
  • You are concerned about the possibility of facing discrimination at work or with some types of future private insurance, such as life insurance, disability insurance, or long-term care insurance. Many people worry that genetic information released to insurance companies may affect future employment options or the cost or availability of private insurance. Results will not affect your health coverage under your provincial health plan.
  • You think there is no point in knowing now because there would be nothing you could do with lifestyle or treatment to prevent the disease.

Other Places To Get Help

Online Resources

Canadian Association of Genetic Counsellors (CAGC)
Web Address:

The Canadian Association of Genetic Counsellors (CAGC) is a professional organization of genetic counsellors, physicians, social workers, and students in related fields.

Canadian Directory of Genetic Support Groups
Canadian Association of Genetic Counsellors (CAGC) and the Children's Hospital at London Health Sciences Centre
Web Address:

The Canadian Directory of Genetic Support Groups provides a resource guide for families and professionals seeking information on genetic support groups in Canada.


Canadian Organization for Rare Disorders
151 Bloor Street West
Suite 600
Toronto, ON  M5S 1S4
Phone: 1-877-302-7273 toll-free
(416) 969-7464
Web Address:

The Canadian Organization for Rare Disorders (CORD) provides information on over 6,000 rare conditions. Through a network system, CORD links together individuals and families with the same rare disorder.

Huntington's Disease Society of America
505 Eighth Avenue
Suite 902
New York, NY  10018
Phone: 1-800-345-HDSA (1-800-345-4372)
(212) 242-1968
Fax: (212) 239-3430
Web Address:

The Huntington's Disease Society of America is dedicated to improving the lives of people who have Huntington's disease and their families. It promotes and supports research and medical efforts to eradicate Huntington's disease and assists families affected by it to cope with the problems it can cause. The Society also provides materials to educate the public and health professionals about Huntington's disease.


Other Works Consulted

  • Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
  • Olanow CW (2008). Hyperkinetic movement disorders. In AS Fauci et al., eds., Harrison's Principles of Internal Medicine, 17th ed., vol. 2, pp. 2560–2565. New York: McGraw-Hill.


By Healthwise Staff
Primary Medical Reviewer Kathleen Romito, MD - Family Medicine
Primary Medical Reviewer Donald Sproule, MD, CM, CCFP, FCFP - Family Medicine
Specialist Medical Reviewer Siobhan M. Dolan, MD, MPH - Reproductive Genetics
Last Revised March 1, 2010

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