Genetic analysis of B_m and AB_m phenotypes

Abstract

ABO blood types include many subtypes and are classified serologically. Variations of ABO blood group phenotypes have been reported predominantly at exon 6 or 7 of the ABO gene. The B_m phenotype is the most prevalent ABO subtype among Japanese individuals and it arises from the partial deletion of intron 1 of the B gene. The deleted region is 5.8 kb or 3.0 kb and includes a transcription enhancer element such as two GATA motifs. We genetically analyzed 17 patients with the B_m or AB_m phenotype using PCR-SSP to detect 5.8 kb or 3.0 kb deletion, and PCR-rSSO to detect variations at exons 6 and 7 of the ABO gene. The 5.8 kb deletion was demonstrated in 16 patients. In the remaining patient, the A and O genes were detected by ABO genotyping using PCR-rSSO. It is very feasible to analyze genetically the ABO gene for the determination of the blood subtype, especially in patients with the B_m phenotype.