“The six SNPs 23andMe examines don’t offer a complete picture of RA disease risk,” explained Dr. Gregersen, who is also principal investigator at the North American Rheumatoid Arthritis Consortium (NARAC), a  research institution jointly funded by the National Institutes of Health and the Arthritis Foundation. “There’s good research showing that all six of those SNPs are associated with an increased risk of RA. But to date, there are roughly 40 SNP regions linked with RA.”

According to Dr. Gregersen, those six, while based on sound scientific literature, only account for about 30 percent of a person’s genetic risk. In fact, while researchers continue to uncover new RA-related genes and SNPs every year, “we still haven’t explained nearly half of the genetic factors relating to RA ,” says Dr. Gregersen.

Plus, genetics aren’t the sole determinant in whether someone develops RA or not. Robert M. Plenge, MD, PhD, a clinical rheumatologist and a human geneticist at the Harvard Partner Center for Genetics and Genomics in Boston, says when it comes to RA, “Just 50 to 60 percent of risk is genetic; the rest is environment, and other factors that we don’t understand.” Translation: even if my genes were picture-perfect, I could still develop it.

A Few Downsides

For the many of conditions a personal genetics test screens for, there’s little to nothing you can do if you find that you have higher-than-average odds. That’s certainly the case for RA, says Dr. Plenge: “So you have an elevated risk. What then? There’s nothing you can do, other than not smoking, to try to lower your chances of getting RA.”

OA also falls under the “un-actionable” umbrella. “OA has less of a genetic component than RA,” says Emilio Gonzalez, MD, a professor of medicine and director of the division of rheumatology at the University of Texas Medical Branch at Galveston. Experts say about 30 percent of the risk of OA is probably genetic. “But even if a [genetic] test revealed that you had an elevated risk, the advice wouldn’t differ from what we tell everyone, regardless of their family history or genes: Keep your weight in check, don’t smoke, and exercise regularly.”

Experts also worry that consumers will arrive at incorrect conclusions based on their genetic test results: “A person could see that the test says she has a higher than average risk of, say, colon cancer, and be falsely alarmed – or conversely, she could see that she has a lower risk, be falsely reassured and choose to forgo crucial screenings such as colonoscopies based on those results,” says Charis Eng, MD, PhD, department chair of the Genomic Medicine Institute at the Cleveland Clinic Foundation in Ohio.

In a new paper in the American Journal of Human Genetics, Jason H. Moore, PhD, professor of genetics and of community and family medicine at Dartmouth Medical School, examined how personal genetic testing companies like 23andMe are using data to judge the health of their customers – and determined that personal genetic testing is, as he puts it, “very premature.”