Men with a particular variant of the Y chromosome have a higher risk of developing coronary heart disease than men with another version of this chromosome, according to a new study.

It's well known that men have a higher risk for heart disease than women. Some of this increased risk may be due to hormonal differences and lifestyle factors, such as smoking.

But the new study shows that differences in the genes found on the Y chromosome, the chromosome that determines the male gender, might also play a role.

Men with different genetic ancestries tend have slightly different genes on their Y chromosomes. Scientists sort these different Y chromosomes into different groups known as "Y-haplogroups." There are about 20 recognized Y-haplogroups, and most are associated with specific regions of the world.

In the current study, Nilesh Samani of the University of Leicester in the United Kingdom and his colleagues examined the link between coronary heart disease and specific variants of the Y chromosome in 3000 British men. Of these men, 1,295 had heart disease and the rest were considered as a control group.

Men with a Y chromosome from the I-haplogroup, who are usually from central, eastern and northern Europe, had a 55 percent higher risk of developing heart disease than the controls.

The increased risk held true even after the researchers took into account other risk factors that might explain the connection, including cholesterol levels, smoking and high blood pressure.

About 12 percent to 15 percent of Caucasian British men belong to the I-haplogroup, and the percentage of American Caucasian men is likely similar, Samani said.

The researchers don't know the mechanism by which this type of Y chromosome puts these men at a greater risk for heart disease, Samani said.

"We know that, from the data we looked at, we don't think it was one of the traditional risk factors," Samani said.

They are currently looking to see whether one of the genes on the Y chromosome might influence the disease risk, Samani told MyHealthNewsDaily.

The researchers would also like to confirm their findings in larger, more diverse populations, he said.

It's far too early to tell whether the genes of the Y chromosome could be used as an indicator of heart disease risk, Samani said.

And even if the link holds true for other populations, a genetic test would do little to help someone manage their disease risk because researchers don't know how the Y-chromosome acts to increase risk. In other words, you couldn't give an individual in the I-haplogroup advice about how to lower their risk that would be specific to their genes.

"In terms of putting it out into clinical practice and having people have a clinical test, you would really want to be able to do something about it," Samani said.

The work was presented at the European Society of Cardiology Congress 2010, which took place Aug. 28 to Sept.1 in Stockholm, Sweden.