A2 erythrocytes lack a antigen modified glycoproteins which are present in A1 erythrocytes

The major blood group antigens A and B are sugars that are expressed on red blood cells, on organ endothelia, and in the body fluids of most individuals.1–3 The biological significance of blood group in nature is unknown, although the distribution of blood groups throughout the world may be explained in part by susceptibility to various diseases.4–5 Blood group is a major consideration in transfusion medicine and organ transplantation because ABO incompatible transfusions and allografts may precipitate catastrophic hemolysis or graft thrombosis resulting in patient death.6–8