Blood groups are determined by the presence or absence of certain antigens on the red blood cells. The ABO blood group system is the most important blood group system in humans, based on the presence or absence of A and B antigens.

One of the four blood groups, AB, is relatively rare and unique because it is the only blood group that expresses both A and B antigens. Despite their rarity, they have some implications on medical risks that they may face.

Increased risk of heart disease

Studies have shown that individuals with AB blood group have a higher risk of developing heart disease than those with other blood groups.

This is because AB blood group carries a higher level of coagulation factor VIII, a protein that helps in the formation of blood clots. Elevated levels of this protein can cause the formation of blood clots, leading to the blockage of blood vessels, which can cause serious cardiovascular problems such as heart attacks, stroke, and deep vein thrombosis.

Increase in the risk of infertility

Studies have linked AB blood group with an increased risk of infertility, particularly in women. The increased risk may be due to the presence of the A and B antigens, which can activate the immune system which may cause implantation failure.

Higher risk of developing pancreatic cancer

AB blood group may also increase the risk of developing pancreatic cancer. Studies have shown that individuals with AB blood group have a 20% higher risk of developing pancreatic cancer compared to individuals with other blood groups.

The reason for this is not yet clear, but it may be linked to the presence of certain genetic factors that are associated with both pancreatic cancer and the AB blood group.

Increased risk of cognitive decline

Recent research has shown that individuals with AB blood group may be at a higher risk of cognitive decline and memory problems as they age.

The study found that individuals with AB blood group were more likely to develop cognitive decline and were three times more likely to develop problems with memory and learning in old age compared to individuals with other blood groups.

Increased risk of stomach cancer

Individuals with AB blood group also have an increased risk of developing stomach cancer. Studies have shown that individuals with AB blood group have a 26% higher risk of developing stomach cancer compared to individuals with other blood groups.

The reason for this increased risk is not yet clear, but it may be linked to the biologic functions of the A and B antigens.

Increased risk of infection

Individuals with AB blood group may be at an increased risk of infection, particularly from Helicobacter pylori, a bacterium that causes stomach ulcers, gastritis, and stomach cancer.

This is because the antigenic determinants present on the surface of the red blood cells of AB blood types resemble those found on the surface of H. pylori. This similarity enables the bacterium to adhere to the stomach lining, which may lead to infection.

Increased risk of venous thromboembolism

AB blood group individuals are also at a higher risk of venous thromboembolism, a condition where blood clots form in the veins, which can cause deep vein thrombosis and a pulmonary embolism.

The increased risk may be due to higher levels of coagulation factor VIII in AB blood group individuals that make blood clotting more likely.

Increased risk of developing liver cancer

Studies have shown that individuals with AB blood group are at a higher risk of developing liver cancer.

The exact mechanism for this is not yet clear, but it may be due to the presence of certain genetic factors that are associated with both liver cancer and the AB blood group.

Increased risk of Alzheimer’s disease

Research has shown that individuals with AB blood group may have a higher risk of developing Alzheimer’s disease than those of other blood types.

The study found that individuals with AB blood group were 82% more likely to develop Alzheimer’s disease compared to those with other blood types. While the exact mechanism for this is not yet clear, it may be related to the effect of blood group antigens on the immune system, which may promote the accumulation of beta-amyloid protein that is a hallmark of Alzheimer’s disease.

Increased risk of developing diabetes mellitus type 2

Studies have shown that individuals with AB blood group are at a higher risk of developing type 2 diabetes mellitus than those of other blood types.

While the mechanism for this is not yet clear, it may be related to the presence of certain genetic factors that are associated with both diabetes and the AB blood group.