O-gene detection by allele specific amplification in the ABO blood group system

ABO genotyping by inverse PCR technique

Inverse PCR technique was applied to type three major alleles (A(1), B and O(1)) of the ABO blood group by simultaneously detecting separated allele-determining nucleotides (the 261st base in exon 6 and the 796th and 803rd nucleotides in exon 7) of the ABO gene. A sequence of about 1.7 kb from exons 6 to 7 of each allele was amplified, both termini of the fragment ligated, and allele-typing performed by the inverse PCR-restriction fragment length polymorphism (IP-RFLP) and allele-specific inverse-PCR (ASIP) methods. For intramolecular ligation, primers for the first PCR were designed to have Acc I-restriction sites within the sequences, and both termini of the 1.7-kb fragment were digested with Acc I. Using the IP-RFLP method, the inverse PCR product was digested with Kpn I, Nla III and Dde I, A(1), B, O(1)-standard (O(A)) and O(1)-variant (O(G)) alleles were detected as 365-bp, 272-bp, 193-bp and 128-bp fragments, respectively. By the ASIP method using four allele-specific primers, 222-bp, 124-bp and 232-bp fragments were amplified from A(1), B and O(1) templates, respectively. These techniques would be applicable to detecting separated polymorphic regions of some other genes.

Extensive polymorphism of ABO blood group gene: three major lineages of the alleles for the common ABO phenotypes

Polymorphism of the ABO blood group gene was investigated in 262 healthy Japanese donors by a polymerase chain reactions-single-strand conformation polymorphism (PCR-SSCP) method, and 13 different alleles were identified. The number of alleles identified in each group was 4 for A1 (provisionally called ABO*A101, *A102, *A103 and *A104 according to the guidelines for human gene nomenclature), 3 for B (ABO*B101, *B102 and *B103), and 6 for O (ABO*O101, *O102, *O103, *O201, *O202 and *O203). Nucleotide sequences of the amplified fragments with different SSCP patterns were determined by direct sequencing. Phylogenetic network analysis revealed that these alleles could be classified into three major lineages, *A/*O1, *B and *O2. In Japanese, *A102 and *B101 were the predominant alleles with frequencies of 83% and 97% in each group, respectively, whereas in group O, two common alleles, *O101 (43%) and *O201 (53%), were observed. These results may be useful for the establishment of ABO genotyping, and these newly described ABO alleles would be advantageous indicators for population studies.