Thank You, Walgreens, for Nixing That Off-the-Shelf DNA Test

Last Updated May 13, 2010 10:50 AM EDT

After some prodding from the FDA, Walgreens (WAG) will not sell a spit-and-send DNA test that assesses a person's chances of becoming obese, developing psoriasis, going blind, or having a baby with cystic fibrosis, Tay-Sachs and other genetic disorders. The move snuffs out the national freakout that would have occurred had this product gotten onto store shelves.

Usually, it's good for consumers to have access to cheap, reliable medical devices that give them more information about their health. (If you've ever gotten one of those bills from Quest Diagnostics or another test lab, you'll know that $30 for an off-the-shelf test kit is a bargain.) But in this case, Pathway Genomics' "Discover Your DNA" kit seems designed to cause more harm than good.

Genetic tests don't correctly predict anything, they only give an indicator of propensity or chances. That means people taking the test might learn that they have a good chance of getting cancer (but not actually develop it) while others would learn they had a low chance (but actually get it). In other words, they'd get information that is actually wrong or at least not useful. Merrill Goozner has a good explanation of this:
... there is not much you can do with the results. Most people are not sophisticated enough to understand the difference between having a statistical propensity to develop a disease and having a sword of Damocles hanging over one's head.
Moreover, negative findings could wind up giving people a false sense of security, the story warned, leading them to abandon lifestyles that ward off disease or foregoing routine screening that might save their lives. Many if not most people develop cancer or Alzheimer's disease through bad luck or environmental exposures, not because they have a bad set of genes.
Call me a Luddite, but if there's one thing I don't want to know it's how or when I might get sick. If Huntington's Chorea lies in my future I'd rather be blissfully ignorant until it arrives.

My other worry is the abuse potential the product carries. All it requires is a saliva sample. It's pretty easy to get hold of someone else's spit. It's not hard to imagine people surreptitiously testing samples from new lovers to see if they're good parent material. Or teenagers sending in stolen samples in order to humiliate their friends with the results.

Lastly, there's a movement afoot to make DNA testing trendy. Two years ago, the NYT reported on 23andMe, a company that holds "spit parties" for DNA testing:
Co-founded by Anne Wojcicki, the wife of a founder of Google, the company, which has token financial backing from Harvey Weinstein and Wendi Murdoch, hopes to make spitting into a test tube as stylish as ordering a ginger martini.
That's one party I don't want to attend. Sometimes, paying a little more for a relevant test that can be properly interpreted by your doctor is actually worth the price.

Image by Flickr user ynse, CC.