June 16 (HealthDay News) -- There's no proof that genetic testing can help prevent the potentially dangerous blood clots called deep vein thrombosis, a new U.S. government report shows.

The presence of two gene mutations called Factor V Leiden and prothrombin G20210A can signal continued risk of blood clots, according to background information in the study.

But Agency for Healthcare Research and Quality (AHRQ) researchers reviewed available scientific literature and said there's not enough evidence to conclude that genetic testing for the two gene mutations in adults with a history of blood clots helps prevent deep vein thrombosis or improves other patient outcomes.

The researchers also said they found no benefit to genetic testing of family members of patients who have at least one of the two gene mutations as well as a history of deep vein thrombosis.

The study appears in the June 17 issue of the Journal of the American Medical Association.

Each year, an estimated 600,000 Americans develop deep vein thrombosis. These blood clots occur most commonly in the legs of people who are immobile for a long period of time, such as when traveling long distances or recovering from surgery. A deep vein thrombosis can break loose and cause a serious lung problem called pulmonary embolism, or a heart attack or stroke.

"While genetic testing shows great promise to improve treatment and prevent disease, this report clearly shows that we need more research and evidence to achieve its full potential. But people can help reduce their likelihood of developing a blood clot by talking with their doctor about precautions," Dr. Carolyn M. Clancy, AHRQ director, said in a news release from the agency.

SOURCE: U.S. Agency for Healthcare Research and Quality, news release, June 16, 2009