title: A new HLA-A9 subtype lacking the Bw4 epitope. Ancestral or revertant allele?
abstract: The HLA-A9 group has been subdivided into three serologically defined splits, A23, A24, and A2403. We have found a new HLA-A9 split antigen, tentatively called A24AK, in the Japanese population. Sequence analysis of A24AK (officially assigned A*2404) showed that this new allele was different from HLA-A*2402, which codes for the common A24 antigen, by seven nucleotides, and the two alleles could be discriminated by the PCR-SSCP method. These nucleotide substitutions are predicted to result in substitution of six amino acid residues at positions 76, 79, 80, 81, 82, and 83. In all HLA-A9-group alleles described to date, this region is known to code for the Bw4 epitope, which is usually localized on HLA-B molecules. However, the new allele lacks the Bw4 coding sequence. Sequencing results are supported by results showing that the lymphocytes from A24AK-positive individuals did not react with anti-Bw4 antiserum. The nucleotide sequence of A*2404 in this region was identical to that of A*0101, A*2601, A*2602, and several other alleles. These findings suggest several possible paths of evolution of this new allele.
authors.affiliation: Department of Research, Japanese Red Cross Central Blood Center, Tokyo.
authors.forename: K
authors.initials: K
authors.lastname: Kashiwase
authors.forename: K
authors.initials: K
authors.lastname: Tokunaga
authors.forename: Y
authors.initials: Y
authors.lastname: Ishikawa
authors.forename: L
authors.initials: L
authors.lastname: Lin
authors.forename: T
authors.initials: T
authors.lastname: Imanishi
authors.forename: T
authors.initials: T
authors.lastname: Akaza
authors.forename: K
authors.initials: K
authors.lastname: Tadokoro
authors.forename: T
authors.initials: T
authors.lastname: Juji
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D001483:Base Sequence; D002648:Child; D005260:Female; D015234:HLA-A Antigens / Q000235:genetics*; D059871:HLA-A24 Antigen; D015235:HLA-B Antigens / Q000235:genetics*; D006239:Haplotypes / Q000235:genetics*; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D010802:Phylogeny; D018807:Polymorphism, Single-Stranded Conformational
chemical_list: D015234:HLA-A Antigens; D059871:HLA-A24 Antigen; C037709:HLA-A9 antigen; D015235:HLA-B Antigens; C042388:HLA-Bw4 antigen