According to the International Society of Blood Transfusion (ISBT), there are 43 different types of blood group systems found in humans. A blood group can be defined as the system that consists of red blood cells along with a set of antigens whose specificity is controlled by specific genes.
The different types of systems that have been identified include the ABO system, Rhesus system, Lutheran system, Dombrock system, MNS system and many more.
The ABO Blood Group System
The ABO blood group system is based on the presence or absence of antigens A and B on the surface of red blood cells. This system was introduced by Karl Landsteiner in 1901. This is the most common blood group types used to distinguish between the types of human blood. According to this system, the blood cells having antigen A on their surface have antibodies against B in their serum which makes them a type A blood group.
Similarly, humans having blood cells with antigen B possess antibodies against A and make them type B blood group. Type O blood group does not contain any antigen on their red blood cell surfaces, but they do have antibodies against both A and B. Lastly, type AB has both the antigens A and B on their cell surfaces but no antibodies in their serum.
The Rhesus System
The Rh blood group system is the second most used system after the ABO system for blood transfusions. It was first found in Rhesus monkeys. According to this system, there are 49 blood group antigens present on the red blood cell surface. Out of the 49, five most important ones are C, D, E , c and e.
If a person possesses the Rh(D) antigen, along with the antigen A, they are considered to be A+. However, if the person does not have Rh(D) antigen but does have the antigen A, they are considered as A-.
The Dombrock Blood Group System
The Dombrock blood group system is based on the presence of two glycoproteins, Doa and Dob, and five antigens Gy(a), Hy, Jo(a), DOYA, and DOMR on the surface of red blood cells. According to a study, 65% of northern Europeans possess the Doa antigen, and the majority of Africans and Asians were found to have the Dob antigen.
The Lutheran Blood Group System
The Lutheran blood group system is based on the presence of Lutheran antigen on the surface of red blood cells. There are 19 antigens that are released as a variation in the BCAM gene. The Lutheran glycoproteins are members of the immunoglobulin superfamily and are majorly involved in the transport of matured red blood cells from bone marrow to peripheral circulation.
The MNS Blood Group System
The MNS blood group system is based on two genes, glycophorin A and B, on chromosome 4 that codes for about 50 antigens. The most important antigens in the system are M, N, S, s and U. It was discovered in 1927 by Landsteiner and his colleagues. The glycophorins A and B are important receptors for cytokines, viruses and bacteria.
Relationship between ABO Blood System and Metabolic Disorders
There have been several studies to mark a relationship between the ABO blood system and certain diseases, such as malaria, cancer, endocrine, cardiovascular and metabolic disorders. Obesity is one of the most common metabolic disorders that is associated with the accumulation of excess visceral fats. What is visceral fat? Visceral fat, also known as organ fat, can be found inside the peritoneal cavity and is composed of adipose depots, which include epididymal, mesenteric, adipose and perirenal fat.
The relationship between obesity and the ABO blood system is still inconclusive. Some results show type O, some type B and some type A to be more prevalent obesity. Larger group studies are required for a solid and conclusive result.
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