Jul 21, 2009 - News

Genetic Variation May Increase Risk of Atrial Fibrillation And Stroke


Researchers have identified a genetic variant that increases risk of atrial fibrillation (AF), an electrical disorder of the heart, which in turn increases risk of stroke.

AF affects one in four people over 40 years old, and stroke is the third leading cause of death in the United States.

In one of two studies, scientists scanned the genomes of 5,806 people from the United States, Iceland and Norway to look for genetic variations associated with AF. The other study combined data from several large studies comprising almost 47,000 people of European ancestry.

Their results, published online this month in Nature Genetics, newly linked one SNP to slightly elevated risk for developing AF in European populations.

Most strokes are caused by a blood clot that blocks circulation to the brain. Because AF causes ineffective beating of the heart, blood can pool and clot in the upper chambers, resulting in stroke if a clot leaves the heart and lodges in the brain. AF increases the risk of stroke four to five times across all age groups and is the cause behind 10 to 15 percent of all blood clot-related strokes.

In the first study, Gudbjartsson et al. studied people of European descent from the United States, Iceland and Norway to reveal that the T version of   a SNP on chromosome 16, is associated with 1.21 times increased odds of AF. This SNP was also associated with 1.11 times increased odds of ischemic stroke and 1.22 increased odds for cardioembolic stroke.

In the second study, Benjamin et al. associated AF with another SNP. Both SNPs are likely to be marking a third genetic variation that actually has a functional effect on AF. Further research will be necessary to identify both the variation and its effect.

Gudbjartsson et al. also assessed the association of AF with the T version of in more than 3,000 Han Chinese, but the association was not significant. They noted that the T allele of this SNP is much more frequent in Han Chinese than in European populations.

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