Your blood type is linked to your risk of having a stroke, study finds
The analysis focused on genetic studies pertaining to ischemic strokes, which occur due to a blockage of blood flow to the brain. (CREDIT: Creative Commons)
A recent meta-analysis led by researchers from the University of Maryland School of Medicine (UMSOM) suggests a potential link between a person's blood type and their risk of experiencing an early stroke.
Published in the journal Neurology, the analysis focused on genetic studies pertaining to ischemic strokes, which occur due to a blockage of blood flow to the brain and typically affect individuals under the age of 60.
Dr. Steven J. Kittner, a Professor of Neurology at UMSOM and co-principal investigator of the study, highlighted the increasing prevalence of early strokes and their significant impact on mortality and quality of life. He emphasized the scarcity of research into the causes of these events.
Manhattan plot of EOS meta-analysis in the EOSC, random effects model, in TRANS ancestry (A) and European Ancestry (B). EOS = early-onset stroke; EOSC = Early Onset Stroke Consortium. (CREDIT: Neurology)
The study, encompassing data from 48 genetic studies involving 17,000 stroke patients and nearly 600,000 healthy controls, aimed to identify genetic variants associated with stroke risk. Researchers observed a correlation between early-onset stroke (before age 60) and a specific region on the chromosome containing the gene responsible for determining blood type (A, AB, B, or O).
Analysis revealed that individuals with blood type A exhibited a higher likelihood of early stroke, while those with blood type O, the most common type, demonstrated a lower risk.
Conversely, individuals with blood type B were more predisposed to both early and late stroke compared to controls. After accounting for sex and other factors, the study found a 16 percent higher risk of early stroke in individuals with blood type A and a 12 percent lower risk in those with blood type O compared to individuals with other blood types.
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Dr. Braxton D. Mitchell, another co-principal investigator and Professor of Medicine at UMSOM, emphasized the significant association between blood type and early stroke risk revealed by the meta-analysis.
However, he cautioned that the increased risk was modest and advised against undue concern or additional medical testing solely based on blood type.
The researchers proposed that the mechanisms underlying the observed association likely involve blood-clotting factors such as platelets, endothelial cells lining blood vessels, and circulating proteins, all of which contribute to clot formation. Previous studies have suggested a higher risk of deep vein thrombosis, a type of blood clot in the legs, among individuals with blood type A.
Association plots showing SNPs associated with EOS at the ABO locus (±50 kb) and the corresponding associations of these SNPs with LOS, VTE, plasma levels of VWF. (CREDIT: Neurology)
Despite these findings, Dr. Kittner stressed the need for further studies to elucidate the precise mechanisms driving the elevated stroke risk associated with blood type A. He pointed out the involvement of various biological factors that warrant deeper investigation.
Blood type and stroke study limitations
A limitation of the study was the relatively low diversity among participants, with around 35 percent of non-European ancestry. The data originated from the Early Onset Stroke Consortium, comprising 48 studies from various regions worldwide.
Association plots showing SNPs associated with EOS at the ABO locus (±50 kb) and plasma levels of factor VIII. EOS = early-onset stroke; LOS = late-onset stroke; SNP = single-nucleotide polymorphism; VWF = von Willebrand factor. (CREDIT: Neurology)
Dr. Mark T. Gladwin, Executive Vice President for Medical Affairs at UM Baltimore, and a Professor at UMSOM, underscored the study's significance in prompting further exploration into the role of genetically determined blood type in early stroke risk. He emphasized the urgent need for preventive measures to mitigate the potentially devastating consequences of early strokes among younger adults.
In addition to Dr. Kittner and Dr. Mitchell, UMSOM faculty involved in this study included Huichun Xu, MD, PhD, Associate Professor of Medicine; Patrick F. McArdle, PhD, Associate Professor of Medicine; Timothy O’Connor, PhD, Associate Professor of Medicine; James A. Perry, PhD, Assistant Professor of Medicine; Kathleen A. Ryan, MPH, MS, Statistician; John W. Cole, MD, Professor of Neurology; Marc C. Hochberg, MD, MPH, Professor of Medicine; O. Colin Stine, PhD, Professor of Epidemiology and Public Health; and Charles C. Hong, MD, PhD, Melvin Sharoky MD Professor of Medicine.
The study was supported by the National Institutes of Health and Department of Veterans Affairs. Researchers from more than 50 institutions worldwide were co-authors on this study.
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