Objective: To investigate serological and genetic characteristics for an individual with cisAB06, an ABO blood subtype.
Methods: Antigens on red blood cells from the ABO blood group discordant individual were validated by monoclonal antibodies. The ABO antibodies in serum were validated by standard A, B, O cells. ABO genes were analyzed by polymerase chain reaction-sequence specific primer (PCR-SSP). Exons 6-7 of A/B genes were amplified with specific PCR, and the products were directly sequenced.
Results: Both A and B antigens were detected on red blood cells from the proband. There was also anti-A antibody in the serum. The result of PCR-SSP has suggested a B/O02 phenotype. Direct sequencing revealed that the gene was cisAB06. Compared with B101 allele, the cisAB06 allele featured a single nucleotide change (G>C) at position 526 which resulted in an amino acid substitution (G176R).
Conclusion: G>C at nt526 of B allele can produce a cisAB06 allele. The serological phenotype of the specimen is therefore type AB.