Men tend to get coronary artery disease much earlier than women. A new study published in the journal Lancet indicates it could be because of genetic markers on the Y chromosome.

Researchers led by Fadi Charchar of Australia’s University of Ballarat analyzed data from more than 3,200 unrelated white men who’d previously participated in U.K. studies. Scientists then examined the genetic markers on the Y chromosome, which is passed on from father to son. Researchers found 15 to 20 percent of the men fell into one of the 13 ancient ancestry branches known as haplogroup I.

Men in this haplogroup all showed a common variant on the Y chromosome, and even when age, body mass, cholesterol, high blood pressure, smoking and other risk factors were taken into account, those individuals were 50 percent more likely to have coronary artery disease than men without the variant.

Haplogroup I has been traced back to hunter-gatherers who arrived in Europe from the Middle East some 25,000 years ago. Today, men with that haplogroup are still more prevalent in the northern areas of western Europe, where coronary artery disease is more common than it is in the southern regions.

While doctors have long believed heart disease runs in families, the new study lends credence to previously observed trends and provides insights into additional lines of research.

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