Gene variation ups heart attack risk in African Americans

A gene variation linked to an increased risk of heart attack has a much greater effect in African Americans than in people of European descent, say researchers based at Icelandic biotech firm deCODE Genetics. The team, who published their findings early online in the journal Nature Genetics, has shown that a particular version of the LTA4H gene confers a moderately increased risk of heart attack in Icelanders and Americans of European descent. However, although rarer in African Americans, the same variant is linked to a three-fold increased risk in this population.

The research builds on previous work by the group, which showed that two versions of a gene called ALOX5AP are linked to an increased risk of both heart attack and stroke. This gene makes a protein called 5-lipoxygenase activating protein (FLAP), which is involved in making substances that trigger inflammation in the body. Research suggests that inflammation may play an important role in triggering heart attacks and strokes, by weakening the fatty build-ups in the arteries and causing blood clots.

In the latest study, the scientists looked at the LTA4H gene, which makes a protein involved in the same biological pathway as FLAP. They studied variations of the gene in more than 2000 Icelandic patients and healthy controls, and found that one particular version, dubbed HapK, is linked to a 40 per cent increased risk of heart attack. They then looked at more than 3000 US people, and found that in those who described themselves as being of European ancestry, the same variant was associated with a 16 per cent increased risk. However, in participants self-identified as African American, those with HapK were 3.5 times more likely to have a heart attack - an increased risk of 250 per cent.

Team leader Kari Stefansson says the discovery could help people work with their doctors to develop 'prevention strategies' aimed at cutting the risk of heart attack. Although the HapK variant is linked to a much greater increased risk in African Americans, it is only present in around six per cent of this group, compared to 30 per cent of Europeans. The authors say this suggests the variant is relatively new in the African American population, reducing the amount of time for the evolution of other genetic factors that might counteract the effects of HapK. DeCODE is currently developing new drugs that target both the ALOX5AP and LTA4H genes.