[Study of 12 blood donors with c.389T>C variant of ABO*A1.01 allele and weak expression of A from Xi'an area].

Objective: To carry out serological and molecular tests on 12 blood donors and family members of one proband with discrepancy results for ABO serological typing.

Methods: Twelve blood donors with ABO discrepancies identified by the Blood Center of Shaanxi Province from March 2015 to December 2023 and family members of one proband were selected as the study subjects. Serological blood typing was carried out to determine their blood phenotype. ABO genotype of the samples was determined by direct sequencing of amplicons of exons 1 to 7 and cloning sequencing of amplicons of exons 6 and 7. This study has been approved by the Ethics Committee of Blood Center of Shaanxi Province (202328).

Results: Serological results showed that 5 samples were Aweak, 4 samples were Aweak with anti-A1 antibody, and 3 samples were AweakB with anti-A1. Direct sequencing and cloning sequencing results showed that all 12 samples had the haplotype ABO*A1.01/c.389T>C, and family studies showed that the allele could be stably inherited. Glycosyltransferase activity in the plasma was decreased in all samples.

Conclusion: The c.389T>C variant of the ABO*A1.01 allele can alter the encoded amino acid p.Leu130Pro, which weakens the activity of A glycosyltransferase, ultimately leading to the weak expression of A antigen.