[Analysis of a 389 T>C variant of α-1,3-N-acetylgalactoseaminotransferase gene].

Objective: To study the effect of a 389T>C variant in the α-1,3-N-acetylgalactosaminyltransferase gene on the expression of A antigen by molecular genetic analysis of an individual with Ax subtype of ABO variant.
Methods: Serological assays were carried out to identify the ABO blood group of the proband. Exons 6 and 7 of the ABO gene were amplified with PCR and directly sequenced. Following identification of the heterozygote site, specific primers were used to determine the haplotype of the ABO gene.
Results: Weak A antigen was detected on red blood cells from the proband. And anti-A and anti-B antibodies were detected in the serum. DNA sequencing has identified heterozygous 261delG and 389T/C variants in exons 6 and 7. By haplotype analysis, two alleles Ax22 and O01 were found. Compared with that of A101, the Ax22 allele had a nucleotide change (T to C) at position 389, which resulted in an amino acid substitution (L130P).
Conclusion: T>C at nt389 of the α-1,3-N-acetylgalactosaminyl transferase gene can result in significant reduction of A antigen activity.