Do-it-yourself DNA testing: Helpful or harmful?

updated 8:29 a.m. ET April 9, 2009

Anna Peterson is only 27, but she's already watched her mother and her aunt develop breast cancer. She also saw her grandmother's eyesight fail from macular degeneration. So Peterson, a graduate student in Ottawa, Ontario, took her health care into her own hands and did what millions of others of all ages are doing: She opted for an at-home genetic test.

When the results from the $985 test from deCODEme arrived in her e-mail, Peterson felt relief learning that she didn't have an elevated genetic risk for macular degeneration.

Yet the test did show a slightly elevated risk for the more common forms of breast cancer. The results, Peterson says, empowered her to make healthier choices. Together with her physician, she'll use that information to advocate for earlier screening for breast cancer — and possibly start getting mammograms at age 30.

“Prevention starts with knowing the odds,” says Peterson. “I now have the opportunity to make lifestyle changes in my 20s, rather than in my 60s.”

Welcome to the brave new world of genetic testing.

Once the exclusive domain of doctors and genetic counselors, DNA analysis is now a do-it-yourself proposition, with several dozen companies marketing tests directly to consumers, claiming that they will allow you to understand your genetic profile. The process is surprisingly simple: Buy a test online, swab the inside of your cheek or spit into a test tube to collect a DNA sample, and then mail it to the company. In return, you'll receive personalized medical information that purportedly allows you to combat disease by making informed choices about your health. Bolstering that promise is new research that shows you can actually turn off genes that promote certain diseases by improving your diet and better managing stress.

People clearly approve of genetic testing. In a recent Prevention.com poll, 87 percent of respondents said they'd want to know which inherited diseases they're at high risk of developing. Moreover, 54 percent said they'd be likely to have a genetic test even if there was no known treatment or way to prevent the disease.

Not ready for prime time
Plenty of companies are eager to meet this demand, selling at-home tests that range in cost from hundreds to thousands of dollars. Some offer tests that have long been available through doctors and genetic counselors — for instance, those that check for BRCA 1 or 2, the genes linked to a small percentage of inherited cases of breast cancer. Newer versions look at your SNPs (pronounced snips, short for “single nucleotide polymorphisms”), the slight variations within DNA that can account for differences in appearance and how we develop diseases.

The companies don't predict that you're going to get, say, cancer or macular degeneration. Rather, you get back a report showing the risk you run, compared with the average person.

Which genetic tests make the grade?      DECENT Tests for diseases with a proven link to single genes. Unlike SNPs (“single nucleotide polymorphisms”) tests, which look at gene variations that may put you at higher risk for diseases, some tests screen for specific gene mutations that have been scientifically proven to either definitively cause a disease or greatly increase your chance of developing one. Some disorders that can be screened for this way include breast cancer, colon cancer, Huntington's (a neurological disorder), and hemochromatosis (when the body stores too much iron). When people concerned about these diseases are trying to protect their privacy, some opt to use at-home versions of tests so the results won't be part of medical records. Companies that offer this type of testing include DNA Direct, Kimball Genetics, and Myriad Genetics.

One of the newest entrants into the at-home arena, Navigenics, recently launched its $2,500 Health Compass test, which looks for markers associated with 23 common conditions — including diabetes, prostate cancer, and Alzheimer's disease — that are "actionable," or able to be prevented or detected early. For an additional $250 per year, subscribers receive personalized updates when relevant genetic research — for instance, the discovery of new SNPs — changes their health outlook.

Health-conscious consumers are clearly enamored with these high-tech tests — they're expected to spend an estimated $6 billion to have their DNA decoded over the next 5 years. But while the business of do-it-yourself genetic testing is booming, experts say this new frontier of medicine isn't ready for prime time. They worry that the field is insufficiently regulated, not all of the tests are reliable, and the information garnered is incomplete and possibly misleading.

“Some tests lack adequate scientific evidence to support their use, and the lack of regulation means there's no way for consumers to separate the good from the bad,” says Gail Javitt, law and public policy director for the Genetics and Public Policy Center at Johns Hopkins University.

The risks of peering into your medical future
Despite an explosion in the discovery of SNPs, most experts say it's too early to make strong links between these tiny genetic variants and the development of diseases.

Which genetic tests make the grade?      CONSIDER WITH CAUTION SNPs tests from companies that use a laboratory certified by CLIA, which sets standards for U.S. clinical laboratories. This accreditation ensures that the company uses laboratories that adhere to standards and guidelines for clinical testing. Companies using CLIA-certified labs include DNA Direct, deCODEme, and Navigenics. Companies that offer genetic counseling. Some genetic tests deal with statistical risk that can be tough to understand and needs to be considered with your family history, so be sure a knowledgeable health professional interprets your test to avoid needless anxiety and any rash medical decisions. Some companies include free online or telephone sessions with certified genetic counselors and send detailed reports to help explain what test results really mean.

That's because the role played by a single mutation is believed to be modest. Rather, it's the interaction between multiple SNPs and factors like diet, exercise, and weight that predispose you to disease — indeed, studies show that lifestyle accounts for about 70 percent of our susceptibility to health problems such as diabetes, heart disease, and some types of cancer.

As a result, “these tests can't accurately predict the risk of developing these complex diseases at the moment,” says David Hunter, MD, ScD, professor of epidemiology and nutrition at the Harvard School of Public Health.

Likewise, some tests that claim to gauge your risk of diseases such as depression examine single genes that explain only a small part of the predisposition to those illnesses.

Critics also note that test results can be tough to interpret, making it difficult to know when and if you should take action.

A Navigenics test told Robert C. Green, MD, PhD, MPH, a professor of neurology, genetics, and epidemiology at Boston University Schools of Medicine and Public Health, that he had a 20 percent above-average risk of developing multiple sclerosis. But the average risk is 0.3 percent, and his was just 0.5 percent. These are both very low risks (3 out of every 1,000 versus 5 out of every 1,000, respectively), yet the results were highlighted in orange, indicating an elevated risk. Green, a geneticist, understood his real risk, but the average person might not, causing needless worry.

Which genetic tests make the grade?      AVOID "Nutrigenomic" tests that promise to identify your risk of certain diseases and then sell you expensive vitamin regimes that are supposedly based on your genetic profile and help you prevent disease. The General Accounting Office, the investigative arm of Congress, looked at a number of these companies and found that some of these recommended supplements cost $1,200 a year and were actually similar to supplements found in stores for $35. In some cases, the vitamins exceeded recommended daily allowances, making them potentially harmful, and regardless of the different DNA sample, the "personalized" supplements sent were all the same. GAO investigators couldn't verify any of the scientific claims made by manufacturers of these tests. Tests from companies without strict privacy policies. Despite last year's passage of the Genetic Information Nondiscrimination Act, which prohibits your insurance company and employer from using your genetic information against you, no laws yet exist to limit what genetic testing companies can and cannot do with a person's genetic information or DNA sample. Be sure that a company securely stores your DNA sample and will not sell it to be used in a research study without your permission. If the company doesn't provide this information on its Web site, ask for it directly. "Using your information without your consent is unethical," says Caroline Lieber, director of the graduate program in human genetics at Sarah Lawrence College. Tests that don't provide documented scientific evidence validating their claims. You should be fully informed about what a test can and cannot say about your health. Companies should make scientific references available on their Web sites to document the data used for the tests. If they don't offer it, ask for it. Even if you have one of the 18 genes linked to diabetes, it's not as if it's hardwired into your DNA and you'll get the disease on your 40th birthday — or even at all.

And consider the flip side: that someone who tests negative for a gene or is told she's at low risk for developing a dreaded disease becomes less motivated to lead a healthy lifestyle.

David Katz, MD, MPH, director of the Prevention Research Center at Yale University School of Medicine, points to a study on premenopausal women given a range of tests to determine their risks of developing heart disease.

Half saw scans of their coronary arteries, which were surprisingly healthy. But despite other risks revealed from triglyceride and blood glucose levels, the group that saw its healthy scans did less to follow recommendations to prevent heart disease.

“We don't want a single test talking people out of taking care of themselves, and this study suggests that can happen,” says Katz.

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.

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