Genetic Testing Can Change Behavior

People who find out they have high genetic risk for cardiovascular disease are more likely to change their diet and exercise patterns than are those who learn they have a high risk from family history, according to preliminary research. The findings, from a personalized medicine study at the Coriell Institute for Medical Research, a non-profit research institute based in Camden, NJ, suggest both a potential benefit of genetic testing–inspiring patients to get healthy–and a misunderstanding of the power of genetics.

The research is part of a larger effort designed to help answer two major questions surrounding genetic testing: how both patients and doctors will react to the information and whether the information can actually improve health outcomes. For example, someone who finds out he has a high genetic risk of diabetes might adopt a fatalistic attitude and stop exercising, or he might be motivated to start a new diet. The answers to these questions are becoming increasingly important as the amount of genetic information available to both patients and general consumers–via direct-to-consumer tests available via the internet–has rapidly grown over the last couple of years.

“We need large prospective studies to determine which aspects of genetic information change behavior and improve outcomes,” said Michael Christman, the institute’s president and chief executive officer, at a conference on consumer genetics last week in Boston. “Genome information won’t be adopted in routine medicine until its shown it does something.”

Volunteers for the Coriell study, launched in 2007, provide information on their family history, medical history, and demographics, as well as a saliva sample for DNA testing. Each participant is screened for about 2 million different genetic variations, as well as 2000 genetic markers in 225 genes linked to drug metabolism. “This is where I think the sweet spot for personalized medicine will be,” said Christman.

Researchers deliver the results through an educational web portal and then survey patients and their physicians to assess how the testing impacts behavior. Patients are given only the genetic information deemed medically actionable, and they choose which results they want to share with their doctors.

In addition to genetic risk, researchers calculate disease risk from an individual’s family history, environmental factors, such as smoking, and comorbid diseases, such as diabetes. All of this information is displayed side-by-side when patients access their results for a particular disease. “We find that’s important for both patients and doctors since people tend to place undue emphasis on genetics,” said Christman.

Patients still seem to consider genetic information to be special, however. Researchers surveyed patients to find out how they reacted to discovering they carry one or two copies of a variation linked to higher risk of heart disease. People with two copies took it “very seriously, making big changes to diet and exercise,” says Christman. That wasn’t true for those with only one copy, or for those whose family history predicted just as high a risk as that conferred by two copies of the risk gene. Researchers haven’t yet determined how genetic testing effects long term health, which will require extensive follow-up.