Did you ever think one swab of your saliva could reveal your ancestry and inherited family traits—and perhaps even predict your risk of developing certain diseases?
It’s true: In 2003, researchers announced the decoding of the entire human genome, the genetic instructions for human life, written in DNA. Barely a decade later, genetic testing has become big business.
Some private companies now offer genetic screening directly to consumers. All you have to do is pay to have a test kit sent to you and then mail back a sample of your saliva to the testing company’s lab, where your DNA is analyzed. Test results are returned to you via mail, phone, or online.
But is direct-to-consumer genetic testing, typically sold online with costs ranging from $100 to a thousand or more, worth the money? Does the information you’ll receive in return have any value—or scientific validity?
Genetic testing is a powerful tool in medicine. Among the most common uses:
• Diagnostic screening. Identifies genetic mutations that can help doctors diagnose or confirm some diagnoses.
• Pharmacogenetic screening. Identifies genetic variants that may affect response to different drugs, including chemotherapies and antipsychotics.
• Predictive testing. Detects genetic mutations that may increase an individual’s risk of developing a range of serious conditions, including [diabetes] and certain forms of cancer.
• Carrier screening. Identifies people who carry a single copy of a gene mutation that can cause a genetic disorder if a carrier conceives a child.
• Prenatal testing. Detects serious chromosomal disorders in a fetus.
Doctor-ordered vs. direct-to-consumer tests
Traditional, doctor-ordered genetic testing, done in conjunction with a specialized lab and a geneticist or a trained genetic counselor, is common. For example, women with a history of breast cancer in their family may be tested for the presence of variations in BRCA1 and BRCA2 genes, which could reveal a high risk of breast and [ovarian cancers]. Doctors also order genetic tests to help in diagnosing certain diseases or predict how patients will respond to particular medications.
Until 2013, U.S. consumers could purchase online direct-to-consumer genetic testing without a doctor’s involvement. Many tests purportedly predicted susceptibility to diseases ranging from diabetes to Alzheimer’s. The U.S. Food and Drug Administration (FDA) stepped in amid concerns about the public health consequences of inaccurate results given that the companies hadn’t obtained the regulatory approval needed to provide health information. The FDA requested that companies like 23andMe discontinue marketing their genetic tests as providing health information. (23andMe complied with the request.)
Many genetic tests sold on the Internet today are still marketed to consumers but require a prescription from a healthcare provider, and there’s no guarantee that the test results are accurate. Some companies that predict the risk of diseases such as diabetes avoid FDA regulations by not labeling their products as direct-to-consumer and requiring that you speak with one of their genetic counselors or watch an informational video. Still, as 23andMe says on its website, “The tests are not intended to diagnose a disease, or tell you anything about your risk for developing a disease in the future.”
For people considering direct-to-consumer genetic tests, says Jehannine C. Austin, Ph.D., president of the National Society of Genetic Counselors, “it’s important to ask questions. A fundamentally important question to ask is: ‘What is the reason that I am seeking testing?’ and then consider whether the test will try to help you address this issue.
Genetic test information often does not provide absolute answers about whether we will or will not develop a disease. Most common health conditions arise as a result of complex interactions of multiple genes with your lifestyle habits, medical history, family background, and environment.”
In fact, most people don’t mention the results to their primary care doctors. In a report in the Annals of Internal Medicine in April 2016, only 27 percent of 1,026 people who had received genetic results discussed the information with their providers.
The remaining direct-to-consumer genetic tests not requiring prescriptions focus on ancestry and nonmedical genetic traits, such as baldness, or a predicted response to certain drugs. Other companies suggest the information can offer insights into how your genes influence your appetite, metabolism, and exercise response, and your body’s ability to process specific nutrients.
The pitfalls of home testing
Some direct-to-consumer companies suggest that the tests can motivate you to follow a personalized wellness plan. But many doctors question whether a direct-to-consumer test will yield clinically meaningful or motivational results and cite some concerns:
• There’s limited or no evidence indicating whether direct-to-consumer tests are accurate, reliable, or of any scientific value. Despite marketing claims that knowing your genetic makeup can improve your health, no long-term studies have indicated that tests can help prevent disease or lead to better treatment or longer lives.
• Different laboratories may yield different results. In 2010, investigators from the Government Accountability Office tested the accuracy of tests by sending the same DNA sample to different home-testing companies—results among companies were often inconsistent or contradictory.
• The tests aren’t a substitute for a doctor’s expertise and judgment. Without a genetics professional to put the results in context with your personal health history, the data reveal little about your future health and are typically broad.
• The tests can’t rule out your risk of any disease. If the test doesn’t detect a variation in a BRCA1 or BRCA2 gene, for example, it doesn’t mean that you won’t get breast cancer.
• Results may leave you with unanswerable questions. If an abnormal gene or mutation appears, you may feel doomed—even though it doesn’t guarantee you’ll get the disease. There’s also the possibility of false-negative or false-positive results. Misinterpretation of genetic variations can lead to unneeded interventions in some circumstances and failure to engage in appropriate interventions in others.
• The risks reported are based mostly on results among Caucasian individuals. If you’re Asian, African, Hispanic, or another ethnicity, the risk data you receive may be inaccurate.
• Most consumers don’t change their health habits upon receipt of test results. Few are motivated to adopt healthier habits, such as improving their diets or increasing physical activity, says an analysis in the BMJ in March 2016. British researchers found no evidence that communicating disease risk affected health behaviors.
• Home genetic tests fall into a gray regulatory area. Most tests haven’t been reviewed by the FDA or any other agency before entering the market, unlike most doctor-ordered tests.
• The tests can be costly. And insurance usually doesn’t cover them.
Start with traditional tests
The science of genetic risk prediction holds great promise, but for now, consumers need to be asking careful questions before engaging in direct-to-consumer tests, says Austin. “It’s natural to be curious about your genetic predisposition, but if you’re looking to learn about your disease risks, any genetic test results should ideally be interpreted in the light of detailed information about family health history by someone with appropriate genetics expertise. So, companies that offer direct-to-consumer genetic testing have a responsibility to offer consumers easy access to a health-care professional like a genetic counselor.”
You can find a local genetic counselor, says Austin, by visiting the National Society of Genetic Counselors website.