I'm skeptical about the emerging trend of marketing genetic tests directly to consumers. Buyers of the home test kits are instructed to scrape cells from the inside of the cheek and send the swab to be analyzed. Eventually, you get the results by e-mail.
A Congressional report made public on July 27, 2006, found that many of the tests give misleading information. The Congressional investigation was conducted by the General Accounting Office (GAO) and looked at four firms that sell DNA tests. Investigators took swabs from two people and sent them to the labs under 14 fictitious names. Based on the disparities in results, the GAO reported that the tests were not clinically valid and the companies made unproven and ambiguous predictions about health. Many of the firms investigated tried to sell their customers "customized" supplements that differ little from vitamins available at any grocery store.
Genuine genetic testing is not a straightforward process, which is why home tests are unlikely to deliver meaningful results, and may be inappropriate if they could. For example, what if a test shows that you have one of the genetic mutations that predispose to breast cancer? Getting that news would certainly make you anxious, and I doubt that many women would want to hear about it via email from a commercial testing firm. Women who have tests ordered by their physicians get the results from genetic counselors trained to analyze the results and all of the options for follow-up. And what if a woman gets a negative result? She may erroneously think that she has nothing to worry about, and neglect basic preventive care – that would be a big mistake, since genetic mutations account for only five to 10 percent of all breast cancers.
I also worry about testing positive for a disease for which there is no treatment. What are you supposed to do with that kind of information except worry?
Another concern with home tests is the fact that they can deliver both false negatives and false positives. You could get bad (or good) news only to learn much later that just the opposite was true. And I certainly wouldn't be comfortable with the knowledge that potentially negative information about my future health is stored in a database that might get into the hands of insurance companies. That could compromise my medical coverage or chances of getting a life insurance policy. I would be skeptical of assurances that the information is secure. What databases are really secure these days?
My feeling is that medical genetics is much too complicated to be left to home testing. If you're concerned that you may have inherited a predisposition to a disease, talk to your physician about the need for genetic testing and the right way to have it performed.
Andrew Weil, M.D.