Genetic test results may not change health habits

NEW YORK — If you learned your DNA made you more susceptible to getting a disease, wouldn’t you work to stay healthy?

You’d quit smoking, eat better, ramp up your exercise, or do whatever else it took to improve your odds of avoiding maladies like obesity, diabetes, heart disease or cancer, right?

The scientific evidence says: Don’t bet on it.

DNA testing for disease risk has recently expanded in the U.S. The company 23andMe recently started selling the nation’s first approved direct-to-consumer DNA tests that evaluate the buyer’s genetic risk for certain disease or conditions. That go-ahead came in April, about three years after it was told to stop selling such kits until it got the OK from regulators.

DNA tests for diseases typically assess genetic predisposition to getting sick. They don’t provide absolute predictions about whether or not a disease will strike. Genetic risk is only part of a person’s overall risk, which includes influence from other things like a person’s lifestyle.

Last year, researchers published an analysis that combined 18 studies of people who got doctor-ordered DNA test results about disease risks. None involved direct-to-consumer tests; participants were drawn mostly from medical clinics or elsewhere.

The result? Getting the DNA information produced no significant effect on diet, physical activity, drinking alcohol, quitting smoking, sun protection or attendance at disease-screening programs.

That fits with other results showing that, on balance, getting the information “has little if any impact on changing routine or habitual behaviors,” said psychologist Theresa Marteau of Britain’s Cambridge University, a study author.