Classification of Standard Alleles of the MN Blood Group System

Background and Objectives: We had classified the M alleles of the MN blood group system into two subtypes, M G (standard M) and M T , based on a G/T substitution in intron 1 of the glycophorin A (GPA) gene. This study provides further study on nucleotide sequences of M G , M T and N alleles to profile the new allele, M T . Materials and Methods: M G , M T and N alleles of the GPA gene were amplified using GPA gene‐specific primers to avoid coamplification of the genes of glycophorins B and E. Then the 5'‐flanking region, exons 1–7 and introns 1–4 of the alleles were analyzed by DNA sequencing. Results: There were 17 nucleotide substitutions and deletions between M G (standard M) and N alleles. Ten of the M T nucleotides were M G ‐type but the other 7 were N‐type. M T allele also showed one base change and one deletion that were observed in neither the M G nor the N allele. Moreover, we found nucleotide substitutions within each allele, allowing further classification of the alleles. Conclusion: By the sequence data of M G , M T and N alleles, the three alleles could be further classified into M101 and M102, M201 and N101 and N102, respectively.