Genetics influence risk of stroke, study finds

Eric Boerwinkle of The University of Texas Health Science Center and his colleagues analyzed the genetic code of more than 19,000 people from the United States and Europe, who took part in four long-term cardiovascular risk studies. The researchers found two genetic variants on chromosome 12 near two genes that are implicated in stroke. One of the variants - WNK1 - helps control blood pressure. The other - NINJ2 - is linked with the body's ability to repair brain injury. The two genes are located next to one another. The researchers found that they both have strong associations with ischemic stroke. This is the most common type of stroke and is caused by blocked blood vessels in the brain.

While Boerwinkle is not clear which gene is implicated, he suspects it is NINJ2. As he notes, the investigators found two single-letter changes in the DNA, known as single nucleotide polymorphisms or SNPs, near NINJ2. These seem to have sent the strongest stroke "signal." The researchers detected SNPs in approximately 20 percent of whites and in about 10 percent of African-Americans. Their findings also suggest that "having just one copy of this genetic variation can raise the risk of ischemic strokes by about 30 percent." Boerwinkle added that it is unlikely that SNPs are the actual cause of stroke, but are probably associated with the actual genetic cause.

Boerwinkle emphasizes, however, that "while this is the first step in unraveling the genetic contributions of this debilitating disease," additional research needs to be done in order to determine exactly which genes are at play. However, he believes the findings, which were recently published in the New England Journal of Medicine, should give drug companies a new target for researching better treatments. Dr. Walter Crochets, deputy director of the U.S. National Institute of Neurological Disorders and Stroke, which supported the study, adds that the results "will lead scientists to direct their attention to new, important biologic mechanisms and hopefully new treatments to prevent stroke." He notes, however, that the findings are not strong enough to suggest patients alter their stroke prevention strategy.

News Release: Scientists uncover genetic risks for stroke  www.reuters.com  April 15, 2009