Race, inflammation and heart disease

Faye Flam:

Two years ago, the company's search for clues to heart attack honed in on a version of a gene involved with inflammation of the blood vessels. While inflammation can help fight infection, too much may also cause fatty plaque in blood vessels to break off, triggering heart attacks.

In Iceland, a predominantly white population, the gene variant was only slightly more common in patients with severe heart disease than in a healthy control group.

To look into a more diverse gene pool, DeCode repeated the analyses at the Hospital of the University of Pennsylvania, along with hospitals in Cleveland and Atlanta, where African Americans were well represented.

The results were surprising.

While the gene variant, called HapK, was fairly common in Americans of European descent, it had little impact on their heart-attack risk. In African Americans, however, the variant was rarely found, but when it was, it was a strong predictor of heart disease and heart attack. The researchers estimated it more than tripled African Americans' risk of heart attack, especially at young ages.

"An awful lot of people who are walking around, seemingly healthy, drop dead of heart attack at 45 or 50," said Penn's Rader. "If we were better at identifying who those people are ahead of time, we could act aggressively to, for example, lower their cholesterol."

Since one of every two Americans will suffer a heart attack over a lifetime, a threefold increase in risk is "huge," Rader said.

DeCode went on to show that HapK is very rare among Nigerians in Africa, suggesting it arose when humans left that continent and intermarried with Europeans. DeCode president Stefansson speculates the variant may have taken hold because it bolstered Europeans' immune systems.

"We are still being modeled by evolution," Stefansson said.

Ethnicity-specific disease risk in African Americans

Confronting ethnicity-specific disease risk

Blacks at risk for heart attacks by more than 250 percent

deCODE Describes Genetic Risk Factor for Heart Attack Conferring Particularly High Risk in African Americans

Heart risk gene hits African Americans hardest