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, B1528 and B1529, 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 B1501 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 B1518 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, B1521, 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 B1501, B1518, and B1513, respectively. Two splits of B75 antigens, B75V (TS-1) and B15N, which have been proposed to exist in the Japanese population were encoded by B1511 and B1502, respectively. Most of the B15 alleles detected in the present study showed positive associations with other locus antigens. Especially, B1502 was strongly associated with Cw8, while B1521 was strongly associated with A34 and Cw6.