Direct-to-consumer genetic testing is understandably alluring. It offers an opportunity to peer into your building blocks and maybe learn something about your future health risks in a manner that's easy and affordable. However, it's often not identical to clinical genetic testing with a physician or a genetic counselor. In addition, depending on the indication and your personal and family history, genetic testing may not even be recommended.
Analyzing Your DNA at Home
DTC genetic testing has emerged as advances in genetic testing allow for faster, cheaper analysis using small samples of DNA. For a few hundred dollars, a DTC genetic testing company will provide data on your risks of carrying certain diseases and your ancestry. By comparison, it often costs $1,000 or more for genetic testing in a clinical setting -- a price patients may pay out of pocket if they haven't yet met their deductible or don't have insurance coverage. Not surprisingly, the popularity of DTC genetic testing is surging, with the global market valued at more than $70 million last year, according to one report; that's up from roughly $50 million in 2014. One company, 23andMe, has even gained Food and Drug Administration approval to provide information regarding whether you're a genetic carrier for some disorders, including sickle cell anemia.
To submit a test sample, consumers typically spit into a tube, secure it and mail it to the company for processing. Some companies send test results back to consumers without any analysis; trying to understand what your raw data means is complicated. Other companies offer to connect customers with genetic counselors for feedback, but sometimes at additional costs.
Unless you opt for DTC genetic testing following a genetic testing recommendation from a physician or genetic counselor, chances are you do not need a DTC test. Yet DTC companies offer testing to anyone willing to buy a kit and submit a sample. By contrast, patients must receive a written order from a physician or another licensed health practitioner for blood tests, prescription drugs and other medical services.
If you get a DTC test, geneticists or counselors will often recommend no additional testing or action when they review results. They may not have recommended testing in the first place because of a low expected disease risk, if they know testing will not yield definitive conclusions or because no intervention is available to prevent that disease anyway. Even when there is a strong rationale to get tested, using a DTC service may trigger more questions than answers. Because DTC test results may be incomplete or insufficient compared to clinical testing, your medical provider may advise more testing.
DTC testing rarely includes the comprehensive analysis of disease-related genes that's provided in clinical settings, which accounts for an individual patient's family history. We aim to do very specific testing for targeted disorders or groups of disorders, allowing us to decide who should have further testing. Genetic counseling helps us decide on the right care at the right time.
Some DTC companies provide information based on single nucleotide polymorphisms, or SNPs, common genetic variations that can act as biological markers for disease. But this should not be taken as a complete analysis of genetic risk, particularly in individuals with a personal or family history of inherited disorders. Analysis of multiple SNPs with results implying increased or decreased risk for certain disorders does not always provide a complete picture. That's because it cannot be compared to full gene sequencing -- which most DTC testing companies do not offer. Individuals with a high risk for a heritable disorder will probably be better served with genetic counseling and gene sequencing.
DTC tests also often fail to provide usable information to your doctor. We may get lists of hundreds of SNPs that are not practical to analyze in the clinic. Health providers who lack the necessary training to interpret genetic testing results, and sometimes even clinical geneticists and genetic counselors, are unable to provide useful feedback based on the results.
Often overlooked is how your testing data may be used. Life, disability and long-term care insurance companies "can (and do) ask for genetic testing results to make decisions about your coverage," with the exception of a few states, as a VICE Media report details. (Health insurance companies and employers are forbidden from using your genetic data to discriminate against you.) Don't be surprised if that DTC test you bought puts you in a position to report that you are predisposed to some disease, negatively impacting your application for an insurance policy. In addition, the DTC company may use your data, applying information related to your genes (albeit not linked to your personal identity) in research, or sell it to drug companies.
Understanding Your Family History
If you want to assess your risk of developing hereditary cancers or other illnesses, instead of jumping into DTC testing, getting a family history is a good first step. You can input your family health history data into the My Family Health Portrait online tool from the Surgeon General to learn about your risk for certain health conditions. A detailed family history can elicit a wealth of information regarding disease risks -- regardless of what your gene tests say. This also helps because any test results need to be analyzed in the context of one's personal and family history.
Next, consult a certified genetic counselor about whether to get tested at all and, if so, what specific test is appropriate. Counselors can inform you about testing options, risks and limitations in how conclusive results can be. Because identified carriers of genetic disorders may have an increased risk of having an affected child if their partner is also a carrier, the counselor can also review risks associated with getting pregnant and provide options for testing during or after pregnancy.
Some may still want to purchase a DTC test after an appropriate medical consultation, whether to save money, because they're simply curious or since comprehensive testing is becoming more available. If that is the path you take, do plan to consult a genetic counselor to break down and explain what your results mean -- specifically in the context of your personal and family history.
Speaking of history, DTC genetic testing companies are well-suited to query about your ancestry, information that is interesting and comprehensible. But as for being able to decipher your own test results -- and what those results might mean for you or your children -- that's not something you can easily do at home.
Pim Suwannarat, M.D., is a board-certified clinical geneticist with the Mid-Atlantic Permanente Medical Group, based in the Washington area. She leads the clinical genetics service for Kaiser Permanente members in Virginia, Maryland and Washington. She specializes in clinical genetics and biochemical genetics. She also works closely with genetic counselors related to prenatal and cancer genetic counseling.