Systematic classification of alleles of the glycophorin A (MN blood group) gene.

Ten alleles (five M and five N alleles) of the MN blood group system with normal antigenicity were found by sequencing the glycophorin A (GPA) gene. This study demonstrates the systematic classification of these alleles to major or minor variations of the standard alleles. GPA-specific fragments ranging from 150 to 3.8 kb in length were amplified from the templates, and exons 1-7 and introns 1-6 were sequenced. The data were analyzed phylogenetically to classify these alleles into major groups or clusters. The ten alleles were grouped into four major clusters M10X (M101-M103), M20X (M201 and M202), N10X (N101-N104) and N20X (N201), where 'X' represents a digit indicating minor variations. This grouping was supported by phylogenetic analysis. The cluster system of GPA alleles is highly informative for genetic screening.