Expert cautions against rushing into genetic testing

Jun 1 2008

Just because scientific advances now allow individuals to learn their genetic make-up doesn't mean they should rush into genetic testing in hopes of making revolutionary improvements to their health, cautions a geneticist and practicing physician at the University of North Carolina at Chapel Hill.

"From a basic science perspective, the advances being made in genomics are important discoveries, but it's unrealistic for individuals to believe those advances can yield meaningful information that will improve their health," said James P. Evans, M.D., Ph.D., professor of genetics and medicine in the UNC School of Medicine. "And even saying 'It's not there yet' is too optimistic. It's going to be a long time before the potential is realized."

Evans, who is also the director of the cancer and adult genetics clinics and the Bryson Program in Human Genetics in UNC's medical genetics department, will talk about how personal genomics will affect human lives at a panel discussion titled "Your Biological Biography" at the World Science Festival (www.worldsciencefestival.com) being held in New York City, May 28 to June 1. Evans will speak between 1 p.m. and 2:30 p.m. on Saturday, May 31, at the Kimmel Center for University Life at New York University.

"The sequencing of the human genome revealed that in relative terms, humans are 99.9 percent the same," Evans said. "But in absolute terms, we are very different. For example, a one-thousandth of a difference in their respective DNA profiles translates into more than 3 million differences between any two unrelated individuals."

Some of these differences are medically relevant, in that they influence disease predisposition and response to drugs, areas Evans studies in his research. And the differences are of interest in non-medical ways, specifically when they address ancestry, behavior traits and the innate curiosity humans have about their genes.

Sequencing of the human genome, which was completed in 2003, also gave rise to commercial entities offering direct-to-consumer genetic testing for a fee, usually between $1,000 and $3,000. Evans worries that individuals may seek such testing with the false hope that they will get meaningful results regarding their risks for disease and actionable medical advice about how to decrease their risks.

"Much of the current excitement about genetics and medical genomics is predicated on the idea that knowing our genomes better will improve our health," Evans said. "In fact, for the vast majority of such risk assessments, the increased risk of an individual developing the disease in question is modest - one- to two-fold over baseline. And in few such conditions are there specific effective interventions to diminish the risk. Further, there is little evidence that having the specific genetic information would actually induce a change in lifestyle."

Society has tended to place an almost mystical association on genetic information, Evans said, adding that what to do with this new knowledge and how to interpret the information presents many unanswered challenges.

"Most physicians, by their own admission, are not geneticists and won't know what to do with the information," said Evans, who uses family history and genetic testing to evaluate and counsel patients about their risk for cancer. "Many who do understand the technology and how it is generated don't know what to do with it. So there's huge potential for patient harm - either for patients to be lulled into a false sense of security by this new genomic information or, in the opposite extreme, to have unnecessarily increased anxiety."

And Evans said he can see even more extreme measures "where interventions are implemented - for example, a total body scan - that put patients on a road to invasive tests that they are better off not getting."

Evans believes these challenges say something about how humans value information, but then fail to scrutinize what it really means. "It's hard for me to over-estimate the beauty and utter significance of sequencing the human genome and other animal genomes," Evans said. "The technology is very promising for all of us, but there is a big gap between having that knowledge and applying it for the betterment of human health."