Huntington's Disease Genetic Test
What is Huntington's Disease?
Huntington disease is a rare condition that causes parts of the brain to break down, or degenerate. It is also called Huntington chorea. The disease causes rapid, jerky body movements and the loss of mental skills ( dementia ). Huntington disease can cause personality changes, behavior 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 behavior changes.
Huntington disease is caused by a change, or mutation, in a 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 disease. Some people may pass on the changed gene to a child before knowing that they themselves have the changed gene.
A blood test can show whether you have the changed gene. You may want to have genetic counseling if you are thinking of having the test. Medical geneticists and genetic counselors 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?
If you have a family member who has Huntington disease, their blood usually is tested first to identify the changed gene that might run in your family. Then you give a blood sample, which is screened for the gene change. Testing another 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 can't tell you when you will develop Huntington disease or how quickly the disease will advance.
Should I Be Tested?
The decision to take the test for Huntington 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 may affect your plans for marriage and 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 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 whether you will someday get Huntington 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 do not have health insurance or you know your insurance would not pay for it.
- You are concerned about the possibility of facing discrimination at work or with future health insurance if your insurance pays for the test. Many people worry that genetic information released to insurance companies may affect future employment options or the cost or availability of insurance. But a law in the United States, called the Genetic Information Nondiscrimination Act of 2008 (GINA), helps protect people who have DNA differences that may affect their health. GINA prevents employers and health insurance companies from using DNA information about people to affect decisions. But it has some limits. For example, this law doesn't apply to life insurance, disability insurance, or long-term care insurance. And it doesn't protect people who work for companies with fewer than 15 employees.
- 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 Works Consulted
- Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
Current as of: December 8, 2019
Author: Healthwise Staff
Medical Review: Kathleen Romito, MD - Family Medicine
Martin J. Gabica, MD - Family Medicine
Elizabeth T. Russo, MD - Internal Medicine
Adam Husney, MD - Family Medicine
Siobhan M. Dolan, MD, MPH - Reproductive Genetics