THE ESSENTIAL
- Adults who suffered an early stroke, before age 60, were more likely to have blood type A.
- People with blood type O had a 12% lower risk of suffering an early stroke compared to those with other blood types.
- “This likely has something to do with blood clotting factors like platelets and cells that line blood vessels as well as other circulating proteins,” according to the authors.
Having a stroke can happen at any age. If the average age of occurrence of a stroke is 74 years, 25% of patients are under 65 and 10% under 45, according to Inserm. In recent years, the number of strokes affecting young people has increased significantly. “These individuals are more likely to die from a life-threatening event, and survivors are potentially at risk of living decades with disability. Despite this, there is little research into the causes of early stroke,” said Steven J. Kittner, professor of neurology at the University of Maryland School of Medicine (United States).
Thus, they wanted to identify the contribution of common genetic variants to the risk of early ischemic stroke. To do this, the team carried out a meta-analysis of 48 cohorts on genetics and early-onset stroke in 18-59 year olds. These included 16,730 cases of stroke and 599,237 adults without stroke. The scientists then examined all collected chromosomes to identify genetic variants associated with early-onset or late-onset stroke, “as well as polygenic risk scores for venous thromboembolism between early and late strokes”.
Early stroke: 16% higher risk for people with blood group A
The results, published in the journal Neurologyrevealed a link between early-onset stroke, occurring before the age of 60, and the area of the chromosome that includes the gene determining whether a blood group is A, AB, B or O. After adjusting for gender and other factors, researchers found that adults with blood type A had a 16% higher risk of having an early stroke than people with other blood types. People with blood type O had a 12% lower risk of having a stroke compared to people with other blood types.
The authors also found that early and late strokes were less likely to occur in adults with blood type B compared to so-called “control” volunteers. Faced with this data, scientists have advised people with blood group A, who are more at risk of having a stroke before the age of 60, to undergo additional examinations or medical tests.
“It probably has something to do with blood clotting factors”
“We still don’t know why blood type A confers a higher risk, but it probably has something to do with blood clotting factors like platelets and the cells that line blood vessels as well as other circulating proteins, all of which play a role in the development of blood clots”, explained Steven J. Kittner. Previous work suggests that people with blood type A have a slightly higher risk of developing blood clots in the legs, called deep vein thrombosis. “We clearly need more follow-up studies to clarify the mechanisms of increased stroke risk,” he added.
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