To investigate serological and genetic characteristics for an individual with cisAB06, an ABO blood subtype.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.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).G>C at nt526 of B allele can produce a cisAB06 allele. The serological phenotype of the specimen is therefore type AB.