Scientific research shows a link between blood type and stroke risk, with people with certain variations of blood type A being more likely to have a stroke before the age of 60. The discovery brings new insight into how genetic peculiarities can influence health.
“This important and surprising finding adds to our current knowledge of nonmodifiable risk factors for stroke, including a person’s blood type,” said, at the time of publication of the study, the doctor and researcher Mark Gladwin, from the University of Maryland.
The researchers analyzed data from 48 genetic studies, which included approximately 17,000 stroke patients and nearly 600,000 healthy individuals aged 18 to 59, reports Science Alert.
The results showed a clear link between the gene responsible for the A1 subgroup and the risk of early-onset stroke.
“The number of people suffering a stroke at a young age is increasing. These events are often fatal, and survivors can remain disabled for decades. However, there is little research into the causes of early strokes,” explained Steven Kittner, lead author and vascular neurologist at the University of Maryland.
Subgroup A1, associated with a 16% higher risk of stroke before age 60
A large-scale genetic analysis has identified two regions of the genome strongly associated with a higher risk of early stroke. One of these corresponded exactly to the genetic region that determines blood type.
The researchers observed that people whose genes coded for a type A variant had a 16% higher risk of having a stroke before age 60 compared to people with other blood types.
In contrast, for those with a gene for group O1, the risk was 12% lower.
However, the specialists emphasize that the additional risk observed in group A is small and does not justify additional medical tests or special monitoring measures.
“We still don’t know why group A would confer a higher risk (of early stroke). It probably has to do with factors involved in blood clotting, such as platelets, cells that line blood vessels and other circulating proteins.” says Kittner.
Results apply differently by age
Another important result of the study comes from the comparison of people who had a stroke before and after the age of 60.
The analysis included about 9,300 patients over 60 who had a stroke and 25,000 healthy people in the same age group.
The researchers found that the increased risk associated with group A was no longer significant for strokes occurring after age 60. This suggests that the mechanisms that trigger an early stroke may be different from those involved in strokes that occur at an older age.
Group B, also associated with a slightly increased risk
The study also showed that people with group B had about an 11% higher risk of stroke, regardless of age, compared to people who did not have a stroke.
Also, the genetic sequences that determine groups A and B have been linked to a slightly increased risk of venous thrombosis (formation of clots in the veins).
Experts say further studies, on more diverse groups, are needed to fully understand the significance of these results.
Even though the results may seem alarming, experts emphasize that blood type is only a small risk factor, and lifestyle, blood pressure, smoking and diet remain the main factors that really influence stroke risk.
