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