Unraveling Your DNA's Secrets
Do-it-yourself genetic tests promise to reveal your risk of coming down with a disease. But do they really deliver?
We sent CyGene a sample of DNA from Tate the dog. The results reported that Tate had a "moderately elevated risk of macular degeneration." Geneticists say dog DNA is similar enough to human DNA to return a result. But dogs don't get macular degeneration.
A 2006 Government Accountability Office study found that nutrigenetic tests, which offer nutritional advice to reduce disease risk–based on your DNA–failed to do so. "Clearly consumers are being misled by this modern-day snake oil," Sen. Gordon Smith, a Republican from Oregon and chairman of the Special Committee on Aging, says of the nutrigenetic tests. Smith and Massachusetts Democratic Sen. Edward Kennedy plan to introduce legislation aimed at imposing tighter controls on all genetic tests.
Patient privacy. Despite the paucity of oversight, some clients say the tests are quite literally just what the doctor ordered. After Susan Smith, 37, of North Carolina had a stillbirth and a miscarriage, her doctor suggested that she take a test for Factor V Leiden, a hereditary disorder that boosts the risk of blood clots. But he proposed that she order the test through DNA Direct so that the results wouldn't be part of her medical record. Smith tested positive. "No one wants to have bad news," she says, "but I felt somewhat liberated by knowing it."
Almost all states have laws offering some protection against genetic discrimination by medical insurers. Federal legislation prohibiting genetic discrimination in employment or insurance has failed to pass Congress. "We get two or three calls a month from people who have lost their jobs or lost their insurance," says Sharon Terry, president and CEO of the Genetic Alliance, a consumer advocacy group.
The DTC genetic testing firms aren't required to protect patient privacy under federal law, as hospital and healthcare facilities must. And there is no guarantee that the firms won't sell or share medical results with insurers or another company. The privacy question cuts another way. A person who hides test results could also miss out on important healthcare–say, more careful reading of mammograms for someone who's BRCA-positive. "It makes for an incomplete medical record that will not be transportable," says Wiesner. "I would submit that that's not modern medicine."
For most people, the odds of having a hereditary disorder are so small that testing doesn't make sense. Elissa Levin, a genetic counselor and clinical director of DNA Direct, says that 40 percent of their clients test positive, a much higher number than would be found in the general population. "The vast majority of people who are testing are testing due to personal diagnosis, family history, or 1 in 5 have a known family mutation," she says. "It's not the worried well."
DNA Direct's most popular test is its $199 screening for hemochromatosis, which elevates iron in the blood and can lead to liver cancer. Ever since a gene that causes the disease was detected in 1996, doctors have debated widespread screening. Sandra Thomas, president of the American Hemochromatosis Society, encourages people who contact her to use DTC tests and thinks that everyone should be screened for the disease, which killed her mother. But a National Institutes of Health study of almost 100,000 people in 2005 found the correlation between gene and disease not strong enough to be useful as a screening tool. The U.S. News staffer, who took the test through HealthCheckUSA, had no family history and came up negative. "Some people have cirrhosis and liver cancer, and some people have the same genetic profile and don't even have iron overload," says Paul Adams, a gastroenterologist at the University of Western Ontario who led the NIH study.
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