Scientists find genes that could raise stroke risk by one-third

Posted April 19, 2009 11:00 pm

Bloomberg News

Two gene variants newly linked to stroke may increase by about 30 percent a person's risk for the third-leading cause of death in the U.S., according to a study of about 20,000 patients.

A genetic region containing the variants was implicated in more than one in 10 stroke cases, according to a study published in the current issue of the New England Journal of Medicine. The variants are located near the so-called NINJ2 and WNK1 genes. NINJ2 is known to be active after a nerve injury, producing a protein that helps determine how well the brain tolerates decreased blood flow, the researchers said. WNK1 is linked with changes in the severity of high blood pressure, they said.

Stroke was the top reason for serious long-term disability in the U.S. in 2008, costing about $65.5 billion in lost wages and medical treatment, according to the American Heart Association. While the risk is three times greater if a parent has had a stroke, previous studies have yielded inconsistent findings about the role of specific genes, researchers said.

"The genes that determine stroke aren't well known," said Donna Arnett, a professor of epidemiology at the University of Alabama at Birmingham who wasn't involved in the study, in a telephone interview. "It definitely tells us something about the physiology of stroke we wouldn't have picked out alone."

Researchers scanned patients' whole genomes to find what was associated with stroke using the Human Genome Project and several large population studies, said Sudha Seshadri, one of the study authors and an associate professor of neurology at Boston University.

The scientists reviewed more than 2 million variations in DNA, called single nucleotide polymorphisms, or SNPs, she said.

Arnett said the test results need to be replicated in other studies. To date, there are no commercial tests to determine if a patient has the genetic variations linked to stroke.

"You can't go to your doctor tomorrow and ask for this test," she said.

Warning signs of a stroke • Numbness or weakness on one side of the body • Sudden confusion • Trouble seeing in one or both eyes • Loss of balance or coordination Risk factors for stroke • Age 55 or older • High blood pressure • Diabetes • Smoking Source: Mayo Clinic

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