“We still don’t know why blood type A would confer a higher risk. But it likely has something to do with blood-clotting factors like platelets and cells that line the blood vessels as well as other circulating proteins, all of which play a role in the development of blood clots,” said senior author and vascular neurologist Steven Kittner from the University of Maryland.
“Specifically, our meta-analysis suggests that gene variants tied to blood types A and O represent nearly all of those genetically linked with early stroke. People with these gene variants may be more likely to develop blood clots, which can lead to stroke,” added study author Braxton D. Mitchell, PhD, MPH, of University of Maryland School of Medicine in Baltimore.
They also noted that those who had blood type O had a 12% lower risk of having a stroke, than people with other blood types.