The<unk>  is a human blood group system based upon two genes (glycophorin A and glycophorin B) on chromosome 4. There are currently 50 antigens in the system, but the five most important are called M, N, S, s, and U. The system can be thought of as two separate groups: the M and N antigens are at one location on the ECM and S, s, and U are on a closely related location. The two groups are very closely located together on chromosome 4 and are inherited as a haplotype.
MNS antigen system
Lewis antigen system
Kell antigen system
Yt antigen system
Ii antigen system
Kidd antigen system
Lutheran antigen system
Colton antigen system