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Immunogenetics

, Volume 53, Issue 3, pp 190–199 | Cite as

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

  • Kenichi Ogasawara
  • Ryuichi Yabe
  • Makoto Uchikawa
  • Kenichi Nakata
  • Junnosuke Watanabe
  • Yuji Takahashi
  • Katsushi Tokunaga
Original Paper

Abstract.

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.

ABO Chimeric allele Polymorphism Recombination Gene conversion 

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Copyright information

© Springer-Verlag 2001

Authors and Affiliations

  • Kenichi Ogasawara
    • 1
  • Ryuichi Yabe
    • 3
  • Makoto Uchikawa
    • 1
  • Kenichi Nakata
    • 2
  • Junnosuke Watanabe
    • 2
  • Yuji Takahashi
    • 2
  • Katsushi Tokunaga
    • 4
  1. 1.Japanese Red Cross Central Blood Center, 4-1-31 Hiroo, Shibuya-ku, Tokyo 150–0012, Japan
  2. 2.Japanese Red Cross Tokyo Metropolitan Blood Center, 1-26-1 Kyonan-cho. Musashino-shi, Tokyo 1800023, Japan
  3. 3.Japanese Red Cross Tokyo West Blood Center, 3256 Midori-cho, Tachikawa-shi, Tokyo 1900014, Japan
  4. 4.Department of Human Genetics, Graduate School of Medicine and Health, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 1130033, Japan

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