Will an At-home DNA Test Tell Me What I Want to Know?
Comparing At-home and Medical-grade DNA Test Options for Health Information
Every day it seems there’s a new at-home DNA test on the market, and two of the biggest testing companies – Ancestry.com and 23andMe – have sold over 30 million tests combined., If you’re considering an at-home DNA test, you may have questions. Can you rely on these tests to give you accurate medical information? Are they something you can use in place of a test ordered at your doctor’s office? If so, what do the results mean?
I have used at-home DNA tests, and as a genetic counselor with expertise in genealogy and ancestry, have learned quite a bit personally and professionally. I have discovered that at-home DNA tests:
1. Aren’t the be-all, end-all: At-home DNA tests don’t cover all the parts of genes that are connected to medical symptoms and conditions. Since these tests only look at parts of your genetic code, the test you get might miss the unique variations that have medical significance for you. Your family or personal history might indicate a different test that looks at another part of your genetic code would be better.
2. Don’t look at the big picture: Your test may come back negative simply because the test didn’t analyze the right thing. Genetic counselors can determine which medical-grade DNA test would be most appropriate for you, based on your personal health history, your family history (if you know it), your ethnicity, and genetic changes that are known in your family. In some cases, your genetic counselor might suggest follow-up testing or screening and management recommendations based on these factors.
3. Give raw data files that can lead you astray: A DNA report that shows nothing out of the ordinary, or even one that raises red flags, may not be accurate because the technology or the interpreting tools got it wrong. If you download and use a raw data file from an at-home DNA company, know that the data hasn’t gone through scrutiny. There can be major and minor problems with reports from these files. One study, for example, showed a high rate (40 percent) of positive findings from at-home testing were not present when retested with a medical-grade test. Other medical testing laboratories and clinicians have reported similar findings, and I even experienced this firsthand when I counseled someone who took her raw data from an at-home test and got mixed information about an increased risk for cancer.
4. May provide a false sense of security: At-home tests aren’t comprehensive, but that may not be obvious at first glance. For example, some people who have a disease-causing variant in a cancer-related gene have been falsely reassured by their 23andMe report, because out of thousands of potential changes, the test looked only at three. Before you choose at-home BRCA testing, learn what it will test for, and more importantly, what it won’t test for, compared to what’s covered by medical-grade testing. What’s happening with BRCA gene testing isn’t an isolated situation and will happen with other genes as more options for at-home DNA testing become available.
As a genetic counselor who has answered hundreds of questions about at-home testing, I’ve found that there is some value in it, but there’s often a mismatch between people’s expectations and what they actually get. At-home DNA tests can provide reassurance or worry, sometimes justified and oftentimes not.
At-home testing has brought greater awareness of the value of DNA for medical care. If you’re considering DNA testing or want to discuss your results from an at-home test, meet with a genetic counselor to review personal and medical history and to learn about your options.
You should be able to schedule an appointment to meet or speak with a genetic counselor within a few days, whether in-person, over the phone, or via video chat. Learn more about what genetic counselors do and if you’re interested, search for an available genetic counselor to work with.
Brianne Kirkpatrick, MS, LCGC, is the National Society of Genetic Counselors Ancestry Expert and founder of Watershed DNA, a private practice specializing in ancestry testing and other at-home DNA tests.