The Allele (c.280A>T) Is Responsible for the Weak A Phenotype.

The allele was found in a 71-year-old Korean male with ABO discrepancy and in his two sons. Although the allele (c.280A>T, I94F) in an AwB case was registered in GenBank, the impact of the I94F mutation of the ABO gene on the activity of A transferase has not been studied. Transient transfection experiments were performed in HeLa cells using , and alleles synthesized by site-directed mutagenesis, and the functional expression level of A antigen was assessed by flow cytometry. The results showed that the and alleles expressed A antigen levels that were 80.28% and 19.32%, respectively, of that of the allele. Our study results demonstrate that the c.280A>T variant is responsible for the weakened expression of A antigen.