Blood Group Determination by Glycosphingolipids
The glycosphingolipids are sugar (Oligosaccharides) containing lipids. They are located
in the plasma membranes of cells, displaying their sugar components to the exterior of
the cell.
Glycosphingolipids are key components of red blood cell membranes that play a vital
role in determining blood group. Glycolipids acts as blood group determinants.
The terminal sugar structure of the glycosphingolipid determines an individual's blood
group, as defined by the ABO blood group system.
The H antigen is a protein found on red blood cells that is a precursor to the A & B
antigens.
Specific glycosyltransferases add terminal sugar residues to the H antigen to form A or B
antigens.
1. Blood Group A: An enzyme called A transferase adds N-acetylgalactosamine (GalNAc) to
the H antigen.
2. Blood Group B: A different enzyme, B transferase, adds galactose (Gal) to the H antigen.
3. Blood Group O: No additional sugars are added due to a non-functional enzyme, so the
H antigen remains unchanged.
4. Blood Group AB: Individuals with both A and B transferase enzymes express both
antigens on their red blood cells.
The ABO gene located on chromosome 9 encodes the glycosyltransferase enzymes
responsible for modifying the glycosphingolipids.
