Human red blood cells can be categorised into different blood groups based on the structure of a surface glycoprotein (antigen)
The A, B and O alleles all produce a basic antigen on the surface of red blood cells
When representing blood group alleles, the letter I is used to represent the different antigenic forms (isoantigens)
- The ABO blood groups are controlled by a single gene with multiple alleles (A, B, O)
The A, B and O alleles all produce a basic antigen on the surface of red blood cells
- The A and B alleles are co-dominant and each modify the structure of the antigen to produce different variants
- The O allele is recessive and does not modify the basic antigenic structure
When representing blood group alleles, the letter I is used to represent the different antigenic forms (isoantigens)
- A allele = IA ; B allele = IB ; O allele = i (recessive)
As humans produce antibodies against foreign antigens, blood transfusions are not compatible between certain blood groups
- AB blood groups can receive blood from any other type (as they already possess both antigenic variants on their cells)
- A blood groups cannot receive B blood or AB blood (as the isoantigen produced by the B allele is foreign)
- B blood groups cannot receive A blood or AB blood (as the isoantigen produced by the A allele is foreign)
- O blood groups can only receive transfusions from other O blood donor (both antigenic variants are foreign)