Home DNA Tests?
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In a move likely to heighten a longstanding controversy about DNA tests for health risks, the U.S. Food and Drug Administration (FDA) has ordered home genetic test maker 23andMe to “immediately discontinue” marketing its saliva collection kit and Personal Genome Service, charging that the company has made claims not backed with solid science.

The FDA warning letter contends that the Google-backed company has failed to show that its $99 test—which claims to check one’s risk for hundreds of diseases and conditions—is safe or effective. The regulators also point out that there could be potential for serious harm if the 23ndme test didn’t work as advertised.

“For instance, if the BRCA-related risk assessment for breast or ovarian cancer reports a false positive, it could lead a patient to undergo prophylactic surgery, chemoprevention, intensive screening, or other morbidity-inducing actions,” the letter states, “while a false negative could result in a failure to recognize an actual risk that may exist.”

In this scenario, if a woman was mistakenly told that she was a carrier of a BRCA1 or BRCA2 genetic mutation that put her at very high risk for breast and ovarian cancer, she might opt for an unnecessary preventive double mastectomy or undergo surgical removal of her ovaries, ending her fertility.

Also alarming is the possibility that women who are genuinely at high risk for these cancers (like Angelina Jolie) might be left dangerously in the dark if the DNA test incorrectly said they were not carriers of BRCA mutations.

It's easy to see the appeal of a simple home test that will uncover lots of interesting facts about your body and predict your risk of disease. But right now, it seems those tests are largely overhyped and can actually threaten your health by giving you false information.

Medically supervised genetic testing (performed in a doctor's office) is still a viable and accurate way to assess health risks for certain patients, but the at-home "direct-to-consumer" tests have been under fire since they hit the market.

A Lack of "Scientific Validity"

The FDA’s action comes after years of controversy about the accuracy of at-home genetic tests—also known as direct-to-consumer (DTC) tests—for health risks, which are offered online by such companies as DNA DTC, DNATraits, and GenePlanet.

One of these firms, DNATraits, had issues with the FDA in 2010, in connection with its Ashkenazi Jews Genetic Test Panel. At the time, 14 makers of genetic tests also received FDA letters, as part of a crackdown that also included an earlier warning to 23andme.

The Federal Trade Commission has long warned consumers that “some [DTC tests] lack scientific validity, and others provide medical results that are meaningful only in the context of a full medical evaluation.”

A recent paper published in the Yale Journal of Biology and Medicine notes that while many common genetic variants have been linked to diseases, the science behind DTC tests may be lacking.  According to a statement from Jeffrey E. Shuren, MD, JD, director of the Center for Devices and Radiological Health at the FDA, “None of the genetic tests now offered directly to consumers have undergone premarket review by the FDA to ensure that the test results being provided to patients are accurate, reliable, and clinically meaningful.”

However, there are many other genetic tests, available only through medical providers, that have received FDA approval or clearance. That means their safety and effectiveness have been rigorously evaluated in clinical studies.

For example, last year, the FDA approved a genetic test to help colorectal cancer patients and their doctors determine if the drug Erbitux would effectively treat their condition.

Genetic Tests Still Valuable, Just Not at Home

According to the FDA, 23andMe has been claiming its test "enables users to  ‘take steps toward mitigating serious diseases’ such as diabetes, coronary heart disease, and breast cancer."

To find out if DNA testing might actually be used this way, I talked to Bradley Bale, MD, medical director of the Heart Health Program for Grace Clinic in Lubbock, Texas. Dr. Bale uses genetic tests in his practice, but not the direct-to-consumer variety.

http://health.yahoo.net/experts/dayinhea...-overhyped
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