Skip to main content
Log in

Recombination and gene conversion-like events may contribute to ABO gene diversity causing various phenotypes

  • Original Paper
  • Published:
Immunogenetics Aims and scope Submit manuscript


We identified five different alleles, tentatively named ABO*O301, *O302, *R102, *R103, and *A110, in Japanese individuals possessing the blood group O phenotype. These alleles lack the guanine deletion at nucleotide position 261 which is shared by a majority of O alleles. Nucleotide sequence analysis revealed that *O301 and *O302 had single nonsynonymous substitutions compared with *A101 or *A102 responsible for the A1 phenotype. Analysis of intron 6 at the ABO gene by polymerase chain reaction-single-strand conformation polymorphism and direct sequencing revealed that *R102 and *R103 had chimeric sequences of A-O2 and B-O2, respectively, from exons 6 to 7. In the analysis of five other chimeric alleles detected in the same manner, we identified a total of four different recombination-breakpoints within or near intron 6. When 510 unrelated Japanese were examined, the frequency of the chimeric alleles generated by recombination in intron 6 or exon 7 was estimated to be 1.7%. In addition, we found that *O301, *A110, *C101, *A111, and 35% of *A102 had a unique A-B-A chimeric sequence at intron 6, presumed to originate from a gene conversion-like event. We had previously established that *A110 also had an A-O2-A chimeric sequence around nucleotide position 646 in exon 7. Thus this allele has an A-B-A-O2-A chimeric sequence from intron 6 to exon 7 probably generated by two different gene conversions. Similar patchwork sequences around nucleotide position 646 in exon 7 were observed in two other new alleles responsible for the Ax and B3 phenotypes. Thus, the site is presumably a hotspot for gene conversion. These results indicate that both recombination and gene conversion-like events play important roles in generating ABO gene diversity.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Similar content being viewed by others

Author information

Authors and Affiliations


Additional information

Electronic Publication

Rights and permissions

Reprints and permissions

About this article

Cite this article

Ogasawara, K., Yabe, R., Uchikawa, M. et al. Recombination and gene conversion-like events may contribute to ABO gene diversity causing various phenotypes. Immunogenetics 53, 190–199 (2001).

Download citation

  • Received:

  • Revised:

  • Issue Date:

  • DOI: