How Blood Type is Determined
The ABO Blood Group System
Introduction to the ABO Blood Group System:
Red Blood cells make (synthesize) several types of surface marker molecules. Because they can induce an immune response in a recipient of transfused blood, these molecules are also known as blood group antigens or agglutinogens.
ABO System of Antigens
- Type A with A antigens only.
- Type B with B antigens only.
- Type AB with A & B antigens
- Type O with H antigens (neither A or B)
As well as the ABO blood group systems, 29 other blood group systems have been identified. These blood groups have names such as Rh, MNSs, Lutheran, Kell, Kidd, and Lewis.
The chemical structures of the A, B and H antigens are very similar.
- Each is a short chain of sugars (oligosaccharide) that is typically attached to a membrane lipid
- They differ, however, at the terminal sugar, and it’s this minor difference that establishes your blood type.
- The ABO blood group antigens are genetically determined, and the incidence of each group varies by race.
The Terminal Sugars of the A,B, and H antigens: