When DNA testing may be warranted
In some circumstances, it's reasonable to consider DNA testing when the genetic tests are performed in conjunction with a health care professional who is knowledgeable in genetic medicine and the DNA test is performed by a specialized lab. DNA testing may be warranted in the following cases:
- Breast cancer: About 2 percent of women have a family history strong enough to warrant testing, according to the U.S. Preventive Services Task Force. If the results are positive, you should have frequent mammograms and other testing (such as MRI), and may even decide to have prophylactic surgery.
- Colon cancer: If you have a strong family history of this cancer, you need frequent colonoscopies to find and remove colorectal polyps. Genetic testing can be helpful in determining if you need even more frequent colonoscopies.
- Dementia: Three rare gene mutations are known to almost always produce early onset of Alzheimer's disease, but account for less than 1 percent of all cases. Another gene is linked to increased risk for the more common late-onset Alzheimer's, though most people who have this gene do not develop the disease. Testing remains controversial, since if you have one of the genes, what can you do? So far there is no way to prevent Alzheimer's.
- Pregnancy: If you are planning a pregnancy and certain disorders run in your family and/or you belong to an ethnic or racial group that tends to have certain disorders (such as Ashkenazi Jews, who are at risk for Tay-Sachs disease, and African Americans, at risk for sickle cell anemia), you should discuss genetic testing with your doctor.
Source: Originally published in The University of California, Berkeley Wellness Letter (February 2011)