Last week, a School of Medicine research team announced that doctors may be able to predict a patient’s risk of having a second (recurrent) ischemic stroke using a simple blood test. Researchers also announced that the blood test in conjunction with a genetic profile could offer the most accurate prediction, helping doctors more easily identify patients at the highest risk.
Led by Stephen Williams, an assistant professor of Neurology and researcher at the Center for Public Health Genomics, the research team sought to determine how genes affect the levels of biomarkers, characteristics collected from the body at measurable levels as an indicator of biological processes, in the blood.
“Having a stroke after your first one is one of the greatest risk factors for death in individuals that have had a stroke," Williams said. “Identifying ways to reduce risk or identify individuals that are at the highest risk is extremely important.”
There are two major types of strokes — ischemic strokes and hemorrhagic strokes. An ischemic stroke results from blockages which prevent blood flow to the brain, while hemorrhagic strokes occur when blood vessels burst and bleed into the brain.
“Both ischemic and hemorrhagic strokes can result in a devastating neurologic deficit and lifelong disability,” Beth Hundt, a clinical nurse specialist in the Neuroscience Center, said in an email statement. “Ischemic strokes are approximately 85 percent of the nearly 800,000 strokes in the U.S. each year.”
The study concerning recurrent ischemic strokes initially began with the failure of a prior clinical trial, “Vitamin Intervention Stroke Prevention Trial,” conducted in the early 2000s, seeking to determine whether treating patients with B12 vitamins could potentially reduce risk for individuals to have a recurrent stroke. Although this treatment was not deemed effective, the study provided genetic information from population of individuals who have had a stroke — a data set from which Williams could draw upon in his own research.
The research team tested seven biomarkers and found genetic influence in only a couple of them, most notably the C-reactive Protein. CRP is an enzyme found in the blood, produced by the liver in response to inflammation. High CRP levels are known to put patients at increased risk for coronary artery disease, which may cause a heart attack.
CRP levels are checked frequently using simple blood tests. Williams’s team determined that there is a shared genetic susceptibility for not only increased CRP but also for increased risk of recurrent stroke.
“What we found was that not only were we able to find that genetics at the CRP gene were important in CRP levels, but the genotype differences at a completely new gene were important when measuring CRP levels,” Williams said.
Because acquiring a genetic profile may be more expensive, it is important to note that even CRP levels alone can be a useful tool in assessing risk after an initial stroke. Blood tests for CRP levels are simple, inexpensive and commonly performed in trying to check for a person’s risk of coronary artery disease.
“I will say that we really are in a kind of rebirth of genetics,” Williams said. “My thought is in the next five to 10 years, every single person will walk into the clinic with a copy of their sequenced genome available to the doctor.”
Williams next aims to identify genes that are important in atherosclerosis, as the hardening of plaque of the artery walls is the single greatest risk factor for having a stroke.