BACKGROUND: The aim of this study was to investigate the serology and gene sequence characteristics of the A307 subgroup of the ABO blood group.

MATERIAL AND METHODS: Monoclonal anti-A and anti-B antibodies were used to detect the ABO antigens of a proband whose positive blood type was not consistent with the negative blood type of the ABO blood group. Standard A-, B-, and O-negative typing cells were used to test for ABO antibodies in the serum. Additionally, polymerase chain reaction with sequence-specific primer (PCR-SSP) was used to confirm the genotype, and subsequently, exons 6 and 7 of the ABO gene were detected by gene sequencing. Samples from the wife and daughters of the proband were also used for serological and genetic testing.

RESULTS: Red blood cells of the proband showed weak agglutination reaction with anti-A antibody, while anti-B antibody was detected in the serum. Moreover, PCR-SSP detected A307 and O02 alleles, while gene sequencing revealed mutation of c.745C>T in exon 7, which produced a polypeptide chain p.R249W. The A307 gene of the proband was not inherited by his daughters.

CONCLUSIONS: A mutation (c.745 C>T) in exon 7 of the ABO blood group gene resulted in low activity of a-1,3-N-acetyl-galactosaminyl transferase, producing A3 phenotype.

Keywords: Antibodies, Monoclonal - immunology, ABO Blood-Group System - immunology, Blood Grouping and Crossmatching - methods, DNA Primers - genetics, Erythrocytes - immunology, Exons, Genetic Association Studies, Polymerase Chain Reaction - methods, Sequence Analysis, DNA