Genetic Testing: Do You Really Want to Know?

The sequencing of the human genome was completed with much fanfare in 2003. Since then, we've been told that we're living in the "genomic era:" the biggest revolution in human health since antibiotics. The beginning of scientific, personalized medicine.

But what does all this actually mean?

First of all, it means we have made tremendous technical advances in isolating and analyzing DNA, dramatically decreasing the difficulty and cost of doing this type of research. Second, we're starting to use some of these genetic techniques every day to screen for or diagnose human diseases, for instance, human papillomavirus infection, which can lead to cancer of the cervix in women.

And third, and most exciting, we're at the beginning of using genomics in pharmacology, both to tell us which drugs will work best in which people and even to design drugs specifically targeted to certain populations.

But unfortunately, the main thing that most of us hear about the genomic revolution comes from news stories about discoveries that associate specific genes with an increased risk for specific diseases. You know: if you have this gene you have an increased risk of prostate cancer. If you have another group of genes, you are more likely to have a heart attack. And so on.

Some companies are even advertising to sell these genetic tests directly to the public, to tell you your risk for a certain disease or for dozens of diseases. There are flashy new websites where, for about $1000, you spit into a tube or scrape your cheek, send in your sample, and in six weeks view your genetic destiny on a special website. These so-called "personal genomic services" promise to "unlock the secrets of your DNA." They say they can tell you your risk for lots of common and less common diseases compared to the rest of the population.

The rub, of course, is what to make of these data. What are you supposed to do with the knowledge that you have a 30 percent increased risk of Alzheimer's disease or a 40 percent decreased likelihood of developing atrial fibrillation? Get really depressed? Start taking medicines? Change your behavior? How?

This is a very tricky business. There is precious little research that tells us what to do with the results of these tests. And what about all of the legal and ethical challenges involved in genetic testing, especially broad genetic surveys? What will happen when the insurance companies get a hold of our genetic profiles?

All of which is not to say that tremendous progress hasn't been made or that these discoveries won't some day revolutionize healthcare. But the day when personalized medicine is a reality rather than a catch-phrase, when the information we get from these tests is useful and not just interesting, still seems a long way off.

Bottom line? Be wary. Examine claims carefully. If you're not an expert in genetic testing, talk with someone who is before getting tested and especially before acting on any genetic test results. It's a jungle out there, and we all need reliable guides.

Family physician Douglas Kamerow, a former Assistant Surgeon General, is a health services researcher and columnist.



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