3 things to know about at-home DNA testing kits
Posted: NOV 12, 2021
About 1 in 5 adult Americans have already taken an at-home genetic test — and it’s easy to see why these kits are so popular.* You get a kit shipped to your home, swab the inside of your cheek, mail in your DNA sample, and get lots of information on your family history and health a few weeks later. It sounds like a fun and simple way to learn more about yourself. But there are a few things you should consider before buying a kit for yourself — or as a gift for friends and family.
Here, Divya Vats, MD, a clinical biochemical geneticist at Kaiser Permanente in Los Angeles, shares what you need to know about at-home DNA tests.
1. An at-home DNA test isn’t as accurate as a medical DNA test.
You’ll get more accurate information from a medical DNA test ordered by your doctor than from an at-home test kit. When a doctor orders a DNA test to assess your risk for disease, there are a few key differences: 1) the way the test is performed, and 2) how your results are analyzed.
With a medical test, your results are analyzed by a molecular geneticist. A molecular geneticist is a medical professional who specializes in DNA, genetic testing, and hereditary diseases.
The molecular geneticist is looking at your DNA for a specific medical reason. “They’re trying to answer a specific health question, like are you at risk for breast cancer, based on your medical history,” says Dr. Vats.
Here’s how it works: A genetic test looks for certain changes in your DNA sequence, called mutations or variants. These variants can be clues that you’re at risk for certain diseases. But even if you have some of these variants, it’s not always a cause for concern. It might not mean anything at all for your health. A geneticist has to look at these variants in relation to lots of other factors to figure out what your test means for you specifically. This means they consider your personal history, medical problems, and family history.
At-home tests, on the other hand, don’t look at your DNA variants in context, or what makes sense for your health, which makes it less accurate. “It only looks at certain markers in your DNA, not the complete sequence,” says Dr. Vats. An at-home test is looking at your DNA from a bird’s eye view, while a medical test is looking at your DNA from a close-up view.
“A medical DNA test can be more targeted in what they’re testing for, and they can take your personal family history and other factors into account,” says Dr. Vats.
2. At-home DNA tests can’t definitively say whether you’ll get a disease.
“Home DNA tests aren’t a good way to learn about your risk for disease,” says Dr. Vats. They only look at a narrow view of DNA markers, so they may miss some important details.
“You shouldn’t make any medical decisions based on the results of an at-home test,” Dr. Vats says. But you can talk to your doctor if you’re concerned about your at-home test results. “Depending on what the marker is, a geneticist can order more specific and reliable testing.”
The genetic counseling you get through a doctor’s office is an important part of genetic testing. Without it, it’s easy to get confused, or end up with a false sense of security or unnecessary anxiety. “For example, it’s possible the results don’t mean anything for your health, but it might mean something for your children’s health,” Dr. Vats explains. A geneticist can help you understand what the DNA test results mean and what you should do about it.
If you’re concerned about a particular hereditary disease, Dr. Vats recommends skipping the at-home test and talking to a genetic professional instead. “They can give you advice and get you the appropriate test — not just a random test like the at-home versions.”
3. At-home DNA tests can help you learn about your ancestry.
“Due to their accuracy issues, don’t do at-home DNA tests to learn about your health,” says Dr. Vats. “But if you want, you can use them to learn about your ethnic background, family origin, and extended family members.”
The ancestry testing you can do with an at-home kit are more reliable than the health testing. The ancestry DNA test looks for genetic markers that are common in certain regions and ethnic backgrounds. For example, you might see that you have 10% of the markers seen in Ashkenazi Jews and 40% of the markers seen in people of Eastern European origin.
The markers can also help you identify extended family members. “Some genetic markers can be seen in half-siblings, cousins, uncles, etc.,” says Dr. Vats. This can help you piece together who you might be related to and your larger family.
Bottom line: At-home DNA tests don’t tell the whole story
If you’re concerned about your health or risk of hereditary diseases, an at-home DNA test isn’t your best option. You’ll get more personalized DNA testing and more reliable results that you can trust from your doctor. If you’re interested in your family background, you can try an ancestry-based at-home DNA test. But you should still consider the privacy risks for you and your loved ones before sending in your DNA sample.
*“Home Genetic Testing: A Nationally Representative Multi-Mode Survey, October 2020 Results,” Consumer Reports, October 2020.