Dear Student,
ABO blood group system was first identified by Karl Landsteiner in 1901.
Basis of classification of the blood groups is the presence or absence of the antigens A and B, which are carried on the surface of the red blood cells(RBC).
There are 4 types of blood groups-
1. TYPE A
2. TYPE B
3. TYPE O
4. TYPE AB
There are 3 forms of genes (alleles) that control ABO blood grouping. These are designated as iA, iB and i.
iA produces the A protein/antigen,
iB produces the B protein/antigen ,
whereas i allele doesn't produce any protein/antigen.
Since humans are diploid, there are 2 alleles present. The ABO blood group alleles show co-dominance, i.e., if allele iA and iB both are present, both get expressed.
BLOOD GROUP | POSSIBLE GENOTYPES | ANTIGEN PRESENT ON RBC | ANTIBODY PRESENT IN PLASMA | DONOR'S GROUP |
TYPE A | iAiA or iAi | A antigen | anti-B | A,O |
TYPE B | iBiB or iBi | B antigen | anti -A | B,O |
TYPE O | ii | A antigen and B antigen | NONE | O |
TYPE AB | iAiB | NONE | anti - A and anti- B | A,B,O,AB |
Knowing blood group is essential to facilitate blood transfusion within compatible blood groups.
Regards