A gene commonly found in Americans of European descent can be deadly when carried by African Americans, a new study has revealed. The gene variant more than triples the risk heart attack in African American populations, the researchers found.
African Americans are known to be more prone to heart attacks and the researchers suggest this may partly be due to European ancestry in those individuals, although environmental factors are certainly involved.
Kári Stefansson at Decode Genetics in Reykjavik, Iceland, and colleagues, isolated a gene variant called HapK, which is found in 30% of European Americans and 6% of African Americans. The variant also occurs in about 35% of people in Asia, but native Africans do not possess the gene. Stefansson proposes that the gene mutation must have occurred after the migration of human populations from Africa, about 50,000 years ago.
HapK is involved in series of biochemical steps that leads to inflammation in the body. Its role is not fully understood but it is believed to increase the propensity of fatty deposits in the arteries - atherosclerotic plaques - to rupture, leading to a heart attack.
250% increased risk
Stefansson studied the significance of the gene variant in more than 3000 people in three groups, one at the Cleveland Clinic in Ohio, one at Emory University in Atlanta, and one at the University of Pennsylvania in Philadelphia, all in the US.
In the study, published in Nature Genetics, they found that HapK was associated with a slight increase in risk of heart attack for participants of European descent - just 16% - while those of African descent were 3.5 times more likely to suffer a heart attack (equivalent to a 250% increase in risk).
"If you're an African American with the variant gene you are close to certain to have a heart attack if nothing is done about it,""It's very important to screen and find this subgroup," Stefansson says. His biopharmaceutical company has two potential drug therapies in clinical trials which act by regulating the inflammatory pathway that HapK is involved in.
Martin Godfrey, a physician at the British Cardiac Society, notes: "There are significant ethnic variations in heart attack risk. Black people in Britain and America are particularly at risk and they have increased incidence of strokes and high blood pressure."
Stefansson speculates that the variant is so dangerous in African Americans because, unlike European Americans, they have not had thousands of years to adjust to its presence in their genome.
"The inflammatory pathway probably developed as a protective response to micro-organisms; and as populations inhabited very different areas, the micro-flora they encountered was vastly different," he says. "That may be the reason for the differences in frequency of the variant."
Journal reference: Nature Genetics
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