The MNS antigen system is a human blood group system based upon two genes (glycophorin A and glycophorin B) on chromosome 4. The MN blood group system is under the control of an autosomal locus found on chromosome 4, with two alleles designated L-M and L-N. The blood type is due to a glycoprotein present on the surface of red blood cells, which behaves as a native antigen. Phenotypic expression at this locus is codominant because an individual may exhibit either one or both antigenic substances. These antigens were an early discovery and are some of the oldest blood antigens known after the ABO system. Anti-M and anti-N antibodies are usually IgM and are rarely associated with transfusion reactions.
Blood Group LM; MN Blood Group