Curious if your genes hold the key to determining your susceptibility to a specific disease? Join the crowd. Annually, thousands of people get their DNA checked – via either a do-it-yourself kit or a clinical DNA test.
But should you consider the results from either test written in stone?
“A positive, negative or inconclusive result does not always indicate clinical diagnosis or absence of disease risk,” says Joshua M. Stone, M.S., LCGC, a certified genetic counselor and manager of cancer genetics at the Einstein Victor Center in Philadelphia, Pa.
Experts recommend that DNA test results be reviewed by a physician with genetics training or a genetic counselor for interpretation along with a person’s health issues, medications, family history and other concerns. In addition, there are instances when DNA results should be reevaluated over time.
When Clinical DNA Results Need a Second Look
If you elect to have a clinical DNA test, your physician or geneticist will collect a sample of blood or saliva from you and send it to a certified lab. Depending on the type of DNA test, the lab will use computer analysis to look at all or part of your DNA and experts will review the results.
“If researchers are 95 percent confident that a change in DNA is disease-causing or not disease-causing, they label the variant either pathogenic or benign, respectively,” explains Stone. “If they are 90 percent confident that a change is disease-causing or not disease-causing, they label the variant either likely pathogenic or likely benign, respectively.”
But, if researchers’ confidence level is less than 90 percent for either benign or pathogenic, you will receive a result termed “VUS.” This three-letter abbreviation stands for “variant of uncertain significance.” It means that there is not enough known about the identified genetic DNA change in the gene or chromosomal region of interest to link it to disease.
So, what do you do with a result that is inconclusive?
“Research linking DNA to disease is a work in progress,” explains Stone. “All of these variants are continuously studied by scientists as we continue to have bigger sample sizes and learn more about genetics and the different variables that cause a gene to lose or maintain its function. That means that, over time, VUSs do get reclassified to pathogenic or benign.”
That makes it imperative you regularly check back with your medical provider about those results.
“Upon learning about a reclassification, clinical DNA labs will contact genetic counselors and physicians to let them know a variant has been reclassified. Checking back with your geneticist on a regular basis to learn about reclassifications should be part of your wellness protocol,” says Stone.
When Consumer DNA Tests Need More Interpretation
Consumers are increasingly interested in managing their health, and that includes learning more about their DNA. According to MIT Technology Review, more than 26 million consumers have already taken at-home DNA tests, known as direct-to-consumer or DTC tests.
But consumers should be aware that DTC tests on DNA for health have varying levels of evidence to back up their claims for validity. In fact, DTC DNA tests provide users with a disclaimer that results should not be used for medical diagnosis.
“DTC testing has certainly brought genetics to the forefront,” says Stone. “DTC testing is convenient but offers only an abbreviated snapshot of one’s genetic makeup and not a full picture, so the data is limited and could be misleading.”
That’s why medical experts agree that if you opt for a DTC genetic test, you should make an appointment with a geneticist or someone who has training to interpret these results. And expect that the geneticist will want to run clinical DNA tests to further investigate.
“Deciding to take a DNA test for health purposes is an emotional experience,” says Stone. “I’m an advocate that you should do so with the guidance of a genetic counselor to help prepare for the various scenarios the test could result in and to understand the impact of those results.”
