An Ounce of Prevention
DNA testing could lead to improved health down the road
Barbara Pfeiffer’s mother and maternal grandmother were both diagnosed with breast cancer in their 40s, as were two aunts. Pfeiffer, 48, of Hoboken, N.J., remembers watching her mother’s 15-year battle with cancer — a valiant fight she eventually lost. So when Pfeiffer had the opportunity to speak with a genetic counselor in 2001 and take a DNA test for the BRCA mutation, which is associated with a particularly aggressive form of breast cancer, she jumped at the opportunity to possibly predict her future.
The $300 test may have saved her life. Pfeiffer tested positive; her odds of having breast cancer were 85 percent. “It may as well have been 100 percent,” she says. “Even though there was a 15 percent chance I could walk away, every female member of my mom’s immediate family had gotten it.” Armed with the knowledge, Pfeiffer could take steps toward, if not prevention, at least early detection.
Since scientists began mapping the human genome, a years-long project finally completed in 2003, more than 1,300 DNA tests have become available — tests that can help determine everything from whether you are lactose intolerant to your odds of becoming obese. Some expose less vital DNA details — whether you’re more suited for running marathons or 5Ks, for example — while other tests can predict serious illness.
Rolling the Dice
Companies such as DeCODEme and 23andMe that provide direct-to-consumer DNA testing offer their clients the hope of finding information on inherited traits to potentially improve quality of life. One company, QTrait, offers an almost recreational approach, with an eclectic array of DNA tests that can tell you whether you’re a night owl or an early bird, if you have more fast- or slow-twitch muscles (better for sprinting or marathon running, respectively), or if you have genetic factors that affect your risk of becoming an alcoholic.
“We don’t want to test people for scary diseases you can’t do anything about,” says Tera Eerkes, chief scientist and CEO of QTrait. “We want to test people for traits for which you can make an active behavioral change and potentially affect the outcome.”
Pfeiffer consulted with a genetic counselor while her mother was having chemotherapy. When the positive results came back, the counselor explained them to Pfeiffer one-on-one during a two-hour appointment. She described what the results meant in terms of Pfeiffer’s preventive care options, which ranged from diligent screening routines to prophylactic surgery. Pfeiffer shared the devastating news with her two sisters so they could also decide whether to test. The genetic counselor walked them through complex medical information as well as the emotional fallout. Pfeiffer’s two sisters subsequently tested negative.
Analyze This
Consumers can pay as little as $99 per test or sign up for a complete body-wide scan for $2,500. Many companies send a simple cheek swab collection kit by mail. You send it back, and in two to six weeks you have access to a detailed DNA crystal ball. But critics contend that just because consumers can use a DNA test to find out whether they’re likely to get multiple sclerosis or osteoarthritis, it doesn’t mean they should.
According to Caroline Lieber, director of the Joan H. Marks Graduate Program in Human Genetics at Sarah Lawrence College, there are two things people need to understand. The first is that if you test positive for a gene, it does not necessarily mean you’ll get the associated condition. And, more important, if the test result is negative, it doesn’t mean you won’t get that disease. “This is not a yes or no kind of thing,” Lieber says.
For example, if a woman has the BRCA gene mutation, her odds of developing breast and ovarian cancer increase dramatically. But with many diseases, such as diabetes, it’s not as clear-cut because single genes associated with those diseases have not been identified yet. What have been identified are multiple markers that are linked in large-population-based studies to a higher incidence of that disease. If you have a certain gene marker for heart disease, you may have only a slightly higher risk of developing it, based on the fact that some people who have the same marker have had heart disease. But a single marker can provide only vague information about which aspect of heart disease you are predisposed to. A problem with the heart muscle? Plaque in the arteries? There’s no way to tell.
Pros and Cons
Lieber says the chief benefit to consumers who undergo some of these DNA marker tests is to heighten awareness so the person can say, “I need to make sure I get my annual physical and EKG since I’m at higher risk” — steps that would be recommended by a physician anyway. Plus, most patients still need doctors and genetic counselors to help them interpret their test results and make appropriate decisions, services most direct-to-consumer testing companies don’t provide.
What’s worrisome about people bypassing their doctor and genetic counselor and using direct-to-consumer DNA testing is that they may walk away from a DNA panel and think they’re all clear. “If people have a family history, I think it becomes really critical to involve their health care professional in deciding whether or not to have these tests done,” Lieber says.
Pfeiffer kept up with diligent preventive screenings for a few years but couldn’t take the uncertainty. “I guess I’m a wimp,” she says. “It’s very difficult to lie there and get your ultrasound. They go over the same spot a hundred and fifty times, and then bring in three more people to look at it.” She says there was never any peace — every screening exam was a nightmare. Three years after her DNA test she’d had enough. She felt it was a matter of when she got cancer, not if. So Pfeiffer decided to go forward with prophylactic hysterectomy, mastectomy, and breast reconstruction — difficult, life-changing decisions that would lower her risk. “You get to a point where you don’t want to wait for the other shoe to drop,” she explains.
No doubt DNA tests signal an exciting time in the medical community. Some companies, like Iverson Genetic Diagnostics, in Puget Sound, Wash., are making patients’ lives better. This year Iverson received FDA approval for a DNA-based test for the drug Warfarin for patients at risk for thrombosis. The test provides information for the appropriate personalized dose based on the patient’s genes. Likewise, the DNA test for BRCA mutations is saving lives and changing the way women like Pfeiffer manage their potential risk of disease. We can expect similar genetic breakthroughs in the future.
— Jennifer Nelson
Before You Swab
Before taking a DNA test, keep these precautions in mind:
- Carefully read privacy and service agreements of do-it-yourself DNA tests.
- Understand what the test can and cannot tell you.
- Look for companies that handle DNA in-house, versus sending it to outside labs.
- Companies should destroy DNA samples after testing and not hold the sample for future research.
- Go with companies that keep personal information separate from DNA samples and provide genetic counselors to help interpret results.
- Information should be deleted from the database at the client’s request.
- If you’re worried that results may hamper future employment or insurance eligibility, check out GINA, the Genetic Information Nondiscrimination Act, signed into law this year, to find out your specific rights. — J.N.
