Test results: helpful or confusing?

Proponents of mail-order genetic testing claim it has just the opposite effect and instead helps people gain new insights that sometimes dramatically boost their health. David Agus, MD, an oncologist and cancer researcher at the University of Southern California, started Navigenics with the hope that people would get tested, discuss results with their physicians, and use the information to seek an earlier diagnosis or delay the onset--or prevent--certain conditions altogether. That's precisely what happened in the case of Mari Baker, the company's CEO. When her results revealed a 5-times-greater risk of celiac disease, follow-up testing ordered by her physician confirmed she has the digestive disease, which is caused by an intolerance to gluten, a protein in wheat, rye, and barley. The diagnosis explained the GI problems Baker, 44, suffered over the years. She immediately changed her diet and stocked her kitchen with gluten-free pasta, bread, and beer. "Feeling a little bit better every day for the next 20 years is pretty important," she says.

Unfortunately, test results aren't always so clear-cut and accurate. Mike Spear, the communications director for a genomic research nonprofit in Alberta, took tests from deCODEme and 23andMe and received some conflicting findings. For instance, the deCODEme test showed a higher-than-average risk for MS, but the 23andMe test said his risk was no higher than that of the average person. The test from deCODEme also had a big check mark next to "male pattern baldness," while the 23andMe test said he was on par with the rest of the population. (Spear, who's 55, still has plenty of hair.) Most surprisingly, both tests told Spear that his risk of asthma was no different from the average person's--even though he already suffers from the disease. His impression: "I'd be careful about basing your life around genetic test results."

Although new genetic research emerges every day, scientists haven't discovered all the genetic variants--or all the SNPs--for common diseases. Green, 54, took two genetic tests, one from 23andMe and the other from Navigenics, and both told him that he had an average risk of cardiac disease. Yet he had undergone triple bypass heart surgery the previous year. As a runner who is not overweight, doesn't smoke, and has low cholesterol, Green suspects there's a genetic cause for his tendency toward blocked arteries--and he chalks up the discrepancy in his test results to the fact that more research is needed to fully understand the genetic causes of cardiac disease.

Another reason to think twice about these tests: The industry is a virtual free-for-all. No single government agency watches the labs performing the tests to ensure that the science behind the tests is even real. Currently, the FDA reviews most other home-use medical tests for safety and effectiveness, but at-home genetic tests don't fall under the agency's territory. Pending legislation would require makers of direct-to-consumer genetic tests to prove that their tests are accurate and properly performed. But right now, "the public's best approach is buyer beware," says Kathy Hudson, PhD, founder and director of the Genetics and Public Policy Center at Johns Hopkins.

Despite these warnings, experts predict that people will be very tempted by the chance to peek into the genetic crystal ball. If you're one of them, heed Katz's reminder: "DNA isn't destiny." And be aware that when it comes to the lifestyle choices that are the greatest predictors of health, your future is in your hands.