Blood type can also affect health! People with blood type A are more likely to have a stroke before the age of 60!

Blood types usually accompany people throughout their lives, in addition to the commonly used ABO blood group classification system, and the Rh blood group system where panda blood (RhD negative) is often used as a bridge in novels, are all distinguished by the type of specific antigen on red blood cells
.
In August last year, Jiangsu also found two cases of the world's rare golden blood group Rh-null, that is, the five most common antigens in the Rh blood group system were all negative, causing temporary concern
.

Before the advent of DNA identification technology, blood type played a significant role
in paternity testing and criminal investigation.
For example, in the ABO blood group system, the production of A and B antigens on the surface of red blood cells is controlled by the three alleles of IA, IB and i, of which IA and IB are dominant to i, based on the genetic laws we know, it can be concluded that one parent is type O blood, it is impossible to give birth to AB blood children and other basic common sense
.
However, there are also extremely rare "exceptions", that is, if the parents are CisAB type (cis-AB type), which is rare in AB type, and the gene mutation causes the AB gene to appear on the same chromosome, it is possible to have children
with the same CisAB type as the spouse of type O blood.

In the fifties of the last century, scientists found that there is a certain association between ABO blood type and disease, and with the advancement of medicine, many subsequent studies have continued to verify this, which is due to the role of A and B antigens, and antibodies in serum that do not target the antigen, play a role
in some diseases 。 In a 2021 review published in Biomed Research International, "Human ABO Blood Groups and Their Associations with Different Diseases," the authors summarized some of the associations between ABO blood types and diseases found in previous studies
.

Fig.
1 Overview of the association between ABO blood group and disease (Source: [1])

In terms of infectious diseases, blood type A is associated with an increased incidence of smallpox and Pseudomonas aeruginosa infections; Blood type B is associated with an increased incidence of gonorrhea, tuberculosis, Streptococcus pneumoniae, Escherichia coli, and Salmonella infections; Blood type AB is associated with an increased incidence of smallpox, E.
coli, and salmonella infections; Blood type O is associated with
an increased incidence of cholera, plague, tuberculosis infection, and mumps.

In terms of non-communicable diseases, the incidence of gastric cancer, ovarian cancer, salivary gland cancer, cervical cancer, uterine cancer and colon/rectal cancer in people with blood type A is higher than that in people with blood type O.
Type B blood has the highest prevalence of type 2 diabetes and hypertension; People with blood group AB are susceptible to an increased risk of cognitive impairment but have a protective effect against hyperlipidemia; People with non-O blood have higher plasma concentrations of coagulation factors vWF and FVIII, and therefore a higher
risk of ischaemic heart disease and thromboembolic disease.

However, the association between ABO blood type and life expectancy is not clear, and there are often opposite conclusions between relevant studies, let alone practical clinical guidance
.
Rumors that people of different blood types are suitable for different dietary recommendations have also been disproved
in the past.

A recent study that pooled data from 48 genetic studies comparing 17,000 ischemic stroke patients with 600,000 non-stroke controls showed that blood type was associated with
an individual's risk of early-onset ischemic stroke.
The findings, "Contribution of Common Genetic Variants to Risk of Early-Onset Ischemic Stroke," were published in Neurology
on August 31, 2022.

Figure 2 Research results (Source: [2])

Ischemic stroke, which is caused by obstructed blood flow to the brain, accounts for 87% of all strokes, while early-onset stroke is defined as occurring
before the age of 60.
The researchers found that chromosomal regions containing genes that determine ABO blood type were linked
to early-onset stroke.
People with blood type A have a 16 percent higher risk of early stroke than other blood types, people with blood type O have a 12 percent lower risk than people with other blood types, and people with both early-onset and late-onset strokes are more likely to have type B blood
than healthy controls.
However, blood type is associated with late-onset stroke much less than blood type is associated with early-onset stroke, suggesting that there may be different mechanisms
behind early-onset and late-onset stroke.
However, the researchers also pointed out that the increased risk of type A blood is actually very small, so there is no need for additional medical tests, and regardless of blood type, a healthy lifestyle can reduce the risk of
stroke.

Steven J.
Kittner, the study's senior author and a professor of neurology at the University of Maryland School of Medicine, said it's still not known why type A blood carries a higher risk, "but it may be related to blood clotting factors, such as platelets and cells that line blood vessels, as well as other circulating proteins, all of which play a role
in the formation of blood clots.
" Previous studies have shown that people with type A blood have a higher risk of deep vein thrombosis, which forms in
the legs.
Although the mechanisms and processes that lead to stroke are different from other types of blood clots, a patient's blood type is indeed related to
the way their body promotes thrombosis.
Early-onset stroke, on the other hand, is more likely to be caused by thrombosis-related factors than by an atherosclerotic process
.

Kittner said more follow-up research is needed to elucidate the mechanisms of increased stroke risk, and perhaps thus find ways
to prevent early-onset strokes.