Question

Write a short note on A ,B, O blood group system in human beings.

Answer 1

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