The Risks of Genetic Tests

Choose direct-to-consumer tests only if you don’t have reason for concern. If something worrisome comes up, talk to your doctor. Here’s what you should know.

Dozens of companies offer tests that cost anywhere from under $100 to more than $2,000 to assess your genetic risk of developing certain illnesses. Their goal is to find variants, also known as “mutations,” tied to diseases. But the science is young, and it is much easier to find a variant than interpret its significance.

There are more than 80 million genetic variants many of them rare or not understood. Even when we know a variant is tied to a disease, we may not know how much it increases risk.

It’s important to know that you can get information about your family ancestry without focusing on medical issues.

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How genetic science is accelerating

To speed research, the U.S. government helped create and fund a global database, ClinVar, with input from 73 countries. As of December 2019, when the database had received a million submissions, it had data on nearly 570,000 unique variants. Expert panels have vetted some 10,000.

ClinGen, another National Institute of Health project, is like an online journal to help researchers and clinicians use genetic information. It’s important to understand that commercial labs and researchers routinely disagree on what a result means.

In fact, every month, ClinVar releases a report listing “conflicting interpretations.” You can see charts on all this information at a web tool called VariantExplorer.

Eric Topol, MD, director of the Scripps Translational Science Institute in La Jolla, Calif., and the author of “The Creative Destruction of Medicine: How the Digital Revolution Will Create Better Health Care,” predicts that if more data is shared, we will encounter fewer mysteries and have more useful information, but this may not happen in time to help you in particular.

Should you get tested?  

If you’re merely curious about what your genes could reveal, be prepared: You’re likely to find a variant suggesting increased risk.

In one study, researchers recruited 199 patients of a large health maintenance organization aged 25 to 40 and offered them free testing of 15 variants associated with increased risk for diabetes, heart disease,  high cholesterol, high blood pressure, lung cancer, colon cancer, skin cancer, or osteoporosis. None of the participants had a current diagnosis for those problems.

After testing, on average, they turned out to carry at least one variant associated with increased risk for six of the eight health conditions. This came to an average of nine risk-increasing variants out of the possible 15.

That may sound scary, but the participants didn’t have a strong emotional reaction. Three months later, only 1 percent had discussed their result with a doctor.

If you have reason for concern, don’t use a direct-to-consumer test. Go through your doctor. You can help scientists by choosing labs that participate in ClinVar. (Patient names remain confidential in the database.)

How genetic counseling can help you

Most people want only genetic information that they can use. It’s increasingly common to run genetic tests when couples are evaluating whether to have a child, especially if there is a family history of genetic conditions or fertility problems. Genetic screening is recommended for all pregnant women. Genetic counselling can also help you evaluate symptoms in a child.

Genetic counselling can help you evaluate symptoms or a family history of hereditary breast and ovarian cancer, Lynch syndrome (colorectal cancer), muscular dystrophy, Huntington’s disease, and sickle cell disease, among other illnesses.

If you take blood-thinners (warfarin, or Coumadin, is common), genetic testing could help target the correct dose for you. As of now, however, genetic testing isn’t required to take the drug, and Medicare doesn’t routinely cover it for that purpose.

Genetic testing can give you the push you need to take precautions. For example, in a small study, people who learned that they carry the APOE ε4 gene, which puts them at higher risk of Alzheimer's disease, were almost six times more likely to have bought long-term care insurance or increased their coverage than people who tested negative.

Research suggests that exercise can help defend you against dementia. Learning you have the gene might push you to use your gym membership.

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