Further molecular diversity in the HLA-B15 group

In order to further clarify the diversity of the HLA-B15 antigens and the correspondence of serological types with alleles in Asians, we screened various B15 serological splits by means of a polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) method. Subsequently, the genes encoding various B15 variants were sequenced. Two novel alleles, B*1528 and B*1529, were identified: the nucleotide sequence of the former contained a single-base substitution at position 263 in exon 2 as compared to that of the B*1501 allele, which results in an amino acid change at position 64 in the alpha 1 domain, and the nucleotide sequence of the latter differs from that of B*1518 by a single-base substitution at position 272 of exon 2 which results in an amino acid change at position 67 of the alpha 1 domain. One new allele, B*1521, described recently in Australian Aborigines was also identified in Asians in the present study. Moreover, the results of sequencing demonstrated that Asian HLA-B62, B70, and B77 antigens are encoded by B*1501, B*1518, and B*1513, respectively. Two splits of B75 antigens, B75V (TS-1) and B15N, which have been proposed to exist in the Japanese population were encoded by B*1511 and B*1502, respectively. Most of the B15 alleles detected in the present study showed positive associations with other locus antigens. Especially, B*1502 was strongly associated with Cw8, while B*1521 was strongly associated with A34 and Cw6.