[Molecular basis of a new O61 allele in ABO blood group]

Objective of this study was to explore the molecular basis of a new O61 allele in ABO blood group. The ABO group antigens on red cells of the blood samples were identified by monoclonal antibodies and the ABO antibody in serum was detected by the standard A, B, O red cells. The coding region sequences of exon 5 to exon 7 in ABO gene were amplified by polymerase chain reaction (PCR) and the amplification products were purified with double enzyme digestion and directly sequenced for exon 6 and 7. The diploid of the individual with B phenotype was separated into its haploid components with a haplotype specific extraction method. The exons 6 to 7 of the two single ABO haplotypes were then amplified and sequenced separately. The results indicated that 3 samples had mutation at 743 site in total 417 individuals, in which 2 individuals were with O phenotype and 1 individual was with B phenotype. The DNA sequencing of exon 6 and 7 in 2 samples with O phenotype showed 261G deletion and 743G/C heterozygotes. The DNA sequencing of exon 6 and 7 in the sample with B phenotype showed 261G/deletion and 297A/G, 526C/G, 743G/C, 657C/T, 703G/A, 796C/A, 803G/C, 930G/A heterozygotes. After separating of the 2 single strands in the B sample with haplotype specific extraction, an O and B101 allele were identified after sequencing. The novel allele was submitted to the Blood Group Antigen Gene Mutation database and is named as O61. It is concluded that 743G>C is a novel mutation in exon 7 of ABO and a novel O61 allele with 743G>C has been identified.