Glycophorin A (GYPA) and B (GYPB; this protein) are major sialoglycoproteins of the human erythrocyte membrane which bear the antigenic determinants for the MN and Ss blood groups respectively. In addition to the M or N and S or s antigens, that commonly occur in all populations, about 40 related variant phenotypes have been identified. These variants include the Miltenberger (Mi) complex and several isoforms of Stones (Sta); also Dantu, Sat, Henshaw (He or MNS6), Mg and deletion variants Ena, S-s-U- and Mk. Most of these are the result of gene recombinations between GYPA and GYPB.