Research has shown that "those with blood type A are more prone to having a stroke before the age of sixty compared to those with other blood types." Blood types describe the rich group of chemicals displayed on the surface of red blood cells. There are four main blood types: A, B, AB, and O. Our blood type (also known as blood groups or blood types) depends on certain antigens, which are molecules that trigger an immune response and are found outside red blood cells. Even within these main blood types, there are slight variations that arise from mutations in the responsible genes.
Genomic researchers have revealed a clear relationship between the A1 subgroup gene and early strokes. Researchers compiled data from 48 genetic studies, involving nearly 17,000 stroke patients and about 600,000 healthy individuals. All participants were aged between 18 and 59. The study revealed that individuals with blood type A were 16% more likely to suffer a stroke before the age of sixty compared to anyone with another blood type. For those with the O1 genotype, the risk was 12% lower. However, the researchers noted that "the increased risks, even for blood type A, were modest and should not cause concern or necessitate further testing."
Lead researcher and vascular neurologist Stephen Kittner from the University of Maryland explained, "We still do not know why blood type A poses a higher risk. But it may be related to blood clotting factors such as platelets and the cells lining blood vessels, in addition to other circulating proteins, all of which play a role in the development of blood clots." Kittner added, "Clearly, we need more follow-up studies to clarify the mechanisms increasing the risk of stroke."
The researchers also compared data from those who suffered a stroke before the age of sixty with those who experienced a stroke after sixty. For this, the team used a dataset of about 9,300 people over age 60 who had experienced a stroke, and around 25,000 individuals over age 60 who had not. They found that the increased stroke risk in blood type A diminished in the late-onset stroke group, suggesting that strokes occurring early in life may have different mechanisms compared to those occurring later.
Researchers stated that strokes in younger individuals are less likely to be caused by the accumulation of fatty deposits in the arteries (a process called atherosclerosis) and more likely to result from factors related to clot formation. The study also found that individuals with blood type B were approximately 11% more likely to suffer a stroke compared to the control group of non-stroke individuals, regardless of age. Previous studies suggest that the part of the genome that encodes for blood type, known as the "ABO locus," is associated with coronary artery calcification, which limits blood flow, and heart attacks. Additionally, the genetic sequence of blood types A and B has been linked to a slight increase in the risk of blood clots in the veins, called venous thrombosis.
