Potential Correlation of Blood Type With Early Onset Stroke Discovered

According to research published in Neurology, data from a meta-analysis shows that a person’s blood type may be linked to their risk of having an early onset stroke.
 
“The number of people with early strokes is rising. These people are more likely to die from the life-threatening event, and survivors potentially face decades with disability.  Despite this, there is little research on the causes of early strokes,” said study coprincipal investigator Steven J. Kittner, MD, MPH, professor of Neurology at University of Maryland School of Medicine (UMSOM).

People who had early onset stroke were more likely to have blood types A or B and less likely to have blood type O. Late-onset stroke was also associated with having blood type B. After adjusting for possible covariates, people with blood type A had a16% higher risk of early-onset stroke and those with blood type O had a 12% lower risk of stroke at any age. 
 
The meta-analysis reviewed data from 48 studies on genetics and ischemic stroke that included 17,000 individuals who had stroke and nearly 600,000 individuals who never had a stroke. All collected chromosome data was used to identify genetic variants associated with a stroke. The observations lead to the finding of an association between early-onset stroke and the area of the chromosome that includes the gene that determines whether a blood type is A, AB, B, or O.
 
“Our meta-analysis looked at people’s genetic profiles and found associations between blood type and risk of early-onset stroke. The association of blood type with later-onset stroke was much weaker than what we found with early stroke,” said study coprincipal investigator Braxton D. Mitchell, PhD, MPH, professor of Medicine at UMSOM.
 
The authors of the study also note that this increased risk in individuals with A blood type is very modest and should not cause worry or lead to additional medical testing at this time.
 
“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 Dr. Kittner. Previous studies suggest that those with an A blood type have a slightly higher risk of developing blood clots in the legs known as deep vein thrombosis. “We clearly need more follow-up studies to clarify the mechanisms of increased stroke risk,” he added.
 
“This study raises an important question that requires a deeper investigation into how our genetically predetermined blood type may play a role in early stroke risk,” said Mark T. Gladwin, MD, executive vice president for Medical Affairs, UM Baltimore, and the John Z. and Akiko K. Bowers distinguished professor and dean, UMSOM. “It points to the urgent need to find new ways to prevent these potentially devastating events in younger adults.”