Blood Type A Linked to Higher Early Stroke Risk
- 12 dic
- 2 Min. de lectura
Adults between the ages of 18 and 59—who may be working, in school, or raising families—are increasingly experiencing sudden neurological events known as early-onset ischemic strokes. These events occur when a blood clot blocks an artery feeding the brain. Seeking answers to why these strokes happen in younger individuals, a team of scientists led by the University of Maryland School of Medicine (UMSOM) conducted a large meta-analysis and a genome-wide association study (GWAS).
The researchers combined data from 48 studies, comparing approximately 16,730 adults who had suffered an early-onset ischemic stroke with nearly 600,000 adults who had not. The genome scan revealed a strong association clustered around one area: the ABO gene, the gene that determines blood types A, B, AB, or O. This genetic connection suggests that clotting-related genetics have a stronger influence on strokes that happen earlier in adult life compared to those occurring at older ages. The association of blood type with later-onset stroke (after age 60) was found to be much weaker.
Genetic and real-world blood type patterns point to specific subgroups affecting risk. Individuals with the A1 blood subgroup were tied to about a 16 percent increase in the odds of suffering an early stroke. Conversely, those with the O1 blood subgroup were linked to a protective effect, showing about a 12 percent reduction in the odds of early stroke.
The ABO gene is known to influence levels of clotting-related proteins, specifically von Willebrand factor and factor VIII. People with non-O blood types generally have higher levels of these proteins, and the A1 subgroup often sits near the high end of that range, which can make clot formation more likely. Researchers suspect that the mechanism driving these early strokes is primarily related to blood coagulation issues, unlike strokes in older adults, which are often caused by the hardening of arteries (atherosclerosis).
While the findings are important and surprising, experts stress that the additional risk conferred by blood type is small overall. The overwhelming majority of strokes—about three out of every four—still occur in people aged 65 and older. Established risk factors like blood pressure, smoking, diabetes, unhealthy cholesterol levels, and lifestyle habits remain far more influential.
These findings add to the current knowledge about non-modifiable risk factors for stroke, such as a person's blood type. Until future research, which needs to include more diverse populations, clarifies the precise biological links, experts emphasize prioritizing traditional stroke prevention: maintaining a balanced diet, staying physically active, and keeping up with regular medical checkups.
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Keywords: Blood type A early stroke risk
Blood type A early stroke risk
