FRIDAY, Jan. 14 (HealthDay News) -- Researchers have simultaneously discovered a gene that seems to raise the risk of cardiovascular disease, while also noting that having the blood type O might guard against heart attack once arteries become clogged.

"Certain genes predispose to heart artery plaque build-up, whereas different genes lead to heart attack when you already have plaque build-up," said study author Dr. Muredach P. Reilly, an associate professor of medicine at the Cardiovascular Institute of the University of Pennsylvania.

One of the more heart-protective genes also helps direct people to have type O blood, the team reported.

The study suggests the multifaceted relationship between genetics and cardiovascular health, Reilly said. "Not all genes for heart disease are equal and therefore have to be used differently in new treatments for heart disease and when assessing risk of heart disease," he said.

The report is published in the Jan. 15 online edition of The Lancet.

For the study, Reilly's team compared almost 13,000 people with coronary artery disease against almost 7,400 people who did not have the condition.

And to hone in on specific genes that might play a role in heart attacks, they compared about 5,800 people with coronary artery disease who had had a heart attack with more than 3,600 people who had coronary artery disease but had never had a heart attack.

Using this method, Reilly's group identified a new gene called ADAMTS7, which was associated with an increased risk of coronary artery disease.

And in the analysis specific to heart attack, they also found an association between blood type and the risk for heart attacks.

Specifically, the gene that makes people have blood type O also protects them from heart attacks, the researchers explained.

Blood is classified as ABO, with eight possible types, determined by the antigens they carry. Type O is know as the universal red cell donor.

"Therapies that modify ADAMTS7 and blood typing may be useful for heart disease, but are likely to work in different ways and different people," Reilly said.

"This concept speaks to future advances in personalized medicine and heart disease treatments. In addition, blood groups might be simple, if crude, indicators of heart attack risk or protection," he said.

But one expert cautioned that while blood type O may offer some protection from heart attack in people with coronary artery disease, that doesn't mean that your blood type alone will spare you from cardiovascular trouble.

"Individuals with blood type O should be just as vigilant about preventing heart disease and stroke as those of other blood types," said Dr. Gregg Fonarow, a professor of cardiology at the University of California, Los Angeles.

Dr. Luca A. Lotta, co-author of accompanying editorial from the Angelo Bianchi Bonomi Hemophilia and Thrombosis Center, Luigi Villa Foundation, University of Milan, said the findings "increase our knowledge of the DNA sequences that predispose individuals to develop atherosclerosis and myocardial infarction."

However, there is no direct and immediate clinical application for the findings, he added.

"But, they may lead in the future to the identification of previously unrecognized disease mechanisms and, potentially, to the development of new preventive and therapeutic strategies for these common and severe diseases," Lotta said.

Fonarow noted that, "it is well-established that there are genetic components to the risk of developing coronary atherosclerosis and myocardial infarction."

However, studies have not shown that genetic testing improves risk stratification or has clinical value in determining which treatment should be given over standard care, he said.

More information

For more information on genes and heart disease, visit the American Heart Association.