A system of universal human blood group isoantigens with many associated subgroups. The M and N traits are codominant and the S and s traits are probably very closely linked alleles, including the U antigen. This system is most frequently used in paternity studies.
Sets of cell surface antigens located on BLOOD CELLS. They are usually membrane GLYCOPROTEINS or GLYCOLIPIDS that are antigenically distinguished by their carbohydrate moieties.