By Will Dunham

WASHINGTON (Reuters) - A study tracking a large group of women for a decade casts doubt on the value of testing for a certain genetic trait linked to heart disease to predict one's chances of illness, U.S. researchers said on Monday.

Knowing a woman had the abnormality on chromosome 9 did not improve cardiovascular illness prediction compared to typical risk factors such as high blood pressure, smoking, cholesterol levels, diabetes, family history of heart attack and C-reactive protein as an indicator of arterial inflammation, they found.

This common genetic trait has been shown to raise the risk for heart attack, stroke and other cardiovascular conditions, and commercial tests for it are available to consumers.

"Once you already know the traditional risk factors, the additional information about the genetic variation doesn't help any. It doesn't improve your ability to predict," Nina Paynter of Brigham and Women's Hospital in Boston, who led the study in the Annals of Internal Medicine, said in a phone interview.

"It definitely suggests that as a population screening tool -- to give it to everybody and add it to what we already know -- the test for this trait by itself doesn't seem to have value," Paynter said.

Genetic tests increasingly are being developed to help people gauge their risk for various ailments, but the value of some such tests has been unclear.

Paynter and colleagues tracked 22,129 U.S. female doctors, nurses, dentists and other health care professionals for 10 years, and determined whether they had the chromosome 9 trait through blood samples given at the outset of the study.

The study confirmed that women with the trait had about a 25 to 30 percent higher chance of getting cardiovascular disease, the researchers said. Scientists have not yet pinpointed the specific gene related to the trait, Paynter said.

Knowing a woman had the trait did not improve the ability to predict whether she had a low, medium or high risk for heart attack, stroke, death from cardiovascular disease or other cardiovascular illness, Paynter said.

Paynter noted that the study did not look at whether a certain targeted group of women might benefit from such testing for this particular trait.

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