Genomic analysis of blood samples with serologic ABO discrepancy identifies 12 novel alleles in a Chinese Han population

Objectives: This study aimed at identifying new ABO alleles from155 unrelated blood samples with potential ABO discrepancy in a Chinese Han population of 835 144 donors.

Background: Serological strategies and genotyping are crucial for the precise determination of ABO discrepancy.

Methods: Their ABO phenotypes and plasma glycosyltransferase activity were determined by standard forward and reverse typing and dilution tests. The genomic DNA of the ABO gene was amplified by polymerase chain reaction and sequenced. The frequency of ABO subgroup alleles associated with ABO discrepancy was analysed.

Results: Serological analysis indicated that 53, 96 and 6 samples with ABO discrepancy were identified in the A, B and O subgroups, respectively. Genetic analysis revealed 12 novel alleles among the 46 associated with serologic ABO discrepancy. The majority of novel alleles was obtained from point mutations or single base insertion in Exons 6 to 7 of the ABO gene. The most frequent alleles were ABO*cisAB.01 (14/53, 26.42%) and ABO*A2.05 (7/53, 13.2%) in the A subgroup and ABO*BA.02 (34/96, 35.42%) and ABO*BEL.11 (15/96, 15.62%) in the B subgroup. Samples with the same ABO subgroup allele displayed different phenotypes, such as ABO*AX.13, ABO*BW.03, ABO*BW.12, ABO*BW.15, ABO*BEL.03, ABO*BEL.10 and ABO*BEL.11.

Conclusion: This study identified 12 novel alleles among the 46 associated with serologic ABO discrepancies. ABO genotyping is needed for the accurate evaluation of blood phenotype to improve the safety of blood transfusion.