Severity of stroke, degree of recovery may not be hereditary

Tuesday, April 06, 2004

Studies have shown that people with a parent or sibling who suffered a stroke have a 30 to 40 percent increased chance of having a stroke themselves. However, new research indicates that the severity of stroke and the degree of recovery may not be influenced by a relative's stroke experience. This finding comes from an interim analysis of data from the first major study of stroke risk genes in an American population.

Dr. James Meschia, a neurologist at Mayo Clinic in Jacksonville, is the principal investigator for the Ischemic Stroke Genetics Study (ISGS). (An ischemic stroke occurs when a blood clot obstructing a blood vessel interrupts the flow of blood to the brain.) "There is intense interest in finding stroke genetic risks factors," Meschia says. "ISGS is the first to systematically study whether family history of stroke predisposes to more severe deficits or slower recovery. Although the observations are sound, these are still interim data. But if you've suffered a stroke, and you have a family history of stroke, it doesn't appear that you'll have a worse outcome."

ISGS investigators are specifically looking at genes involved in the blood clotting process. The gene profile of each stroke victim in the study is compared to that of a stroke-free, age and gender-matched volunteer. Investigators can associate the risk of stroke with a particular gene variation by looking at the frequency and distribution pattern of that gene variant. A gene variation (polymorphism) found frequently in those who had a stroke but not in the stroke-free subjects would be associated with a high degree of stoke risk.

Investigators say identifying genetic patterns associated with stroke will ultimately open up channels to screen those at risk for stroke and get them on the correct preventative treatment. "Aspirin and other clot-blocking drugs don't work for everyone," says Dr. Thomas Brott, a Mayo Clinic neurologist and ISGS co-investigator. "This study may uncover genetic answers to tailor the best treatments for the individual patient."

Roy Beagle remembers one morning last month when he woke up, but his hand didn't. "I rolled over and my hand hit me in the face, like it was asleep," says the 61-year-old executive. "I worked to get my fingers to come around. That must have taken me 30 to 45 minutes. I finished getting ready for work but still didn't have the dexterity that I needed. I'd reach for the telephone and pick up the entire base, or reach for the steering wheel and a couple fingers would drag across it." He called his physician who told him to go to St. Luke's Hospital. To Beagle's surprise, a CT scan and MRI confirmed he suffered a stroke. Fortunately he recovered. He has since enrolled in ISGS. "I'm willing to participate in anything that will help," Beagle says. "Maybe there'll be a drug one of these days that will prevent it from happening again."

ISGS co-investigator Dr. Scott Sillman is the director of the Comprehensive Stroke Program at Shands Jacksonville. He says results of genetic risk studies "may allow us to develop specific drugs targeted at people with a specific genetic profile that will significantly reduce their risk of stroke."

Last year, researchers discovered that the gene PDE4D increased risk of ischemic stroke in the people of Iceland. However, investigators have yet to confirm that the gene plays a role in stroke risk in other populations. "Genetic risk factors found in Iceland may not be applicable here," Meschia says. "If we don't want all the new drugs based on findings in Iceland, it's important to study genetic risk factors in the diverse American population."

ISGS investigators at participating centers, including Mayo Clinic in Jacksonville and Shands Jacksonville, continue to recruit healthy volunteers who have never had a stroke. Participants meet once with a study coordinator for a brief, face-to-face interview and to give a blood sample. Stroke-free, healthy volunteers interested in participating may call Kristen Strecker at (904) 953-7549.

ISGS is sponsored by the National Institute for Neurological Disease and Stroke.

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