Abstract

A B S T R A C T Objective This study aimed to observe the distribution of individuals with ABO discrepancies among Han Chinese patients in Nantong, China, and to analyze the molecular mechanisms of weak ABO expression. Methods ABO group tests were conducted on patient samples collected in three Tertiary hospitals in Nantong from January 1, 2021 to March 31, 2025. Discrepancies were confirmed by other serological methods. If the discrepancy was confirmed, ABO genotype was determined to detect which alleles were present. Results In this study, 412,513 patients were routinely typed for ABO, among whom 1465 ABO discrepancies were identified, including 1,210 cases with unexpected positive results in reverse typing and 255 cases with weak ABO expression. Among these 255 cases, who were not related by blood, there were 10 cases caused by subgroup alleles, including 8 cases of ABO subgroup and 2 cases of Para-Bombay phenotype. The most common allele among the 8 cases of ABO subgroup was ABO*BA.02 . Moreover three cases with other alleles were also identified, ABO*A2.01 , ABO*AW.37 and ABO*BW.27 . Two ABO nucleotide sequences of c.1016   T>C and c.543   G>C, which haven't been included in the ISBT, have already been submitted to the NCBI and acknowledged by the NCBI (GenBank: PQ050610.1, PQ050611.1). Conclusion The main reasons of ABO discrepancies in Nantong are unexpected red cell antibodies including autoantibodies and alloantibodies, and ABO subgroups. These sources of ABO discrepancies need to be identified to ensure the accuracy of tests for ABO.