HLA-B*15 subtypes in the population of north-eastern Thailand.

The HLA-B*15 group is the most polymorphic HLA-B allele and so has several subtypes. These subtypes have not been defined in the population of north-eastern Thailand (NET). In a previous study, using polymerase chain reaction-sequence-specific primers (PCR-SSP), subtypes were categorized into four groups, namely: group I: HLA-B*15 (01, 04-07, 12, 14, 19, 20, 24, 25, 26N, 27, 32, 33, 34 and 35); group II: HLA-B*15 (02, 08, 11, 15, 28 and 30); group III: HLA-B*1503/4802; group IV: HLA-B*1521. Groups I and II occurred frequently (allele frequency = 8.0 and 2.5%), and thus we optimized the polymerase chain reaction-single-stranded conformation polymorphism (PCR-SSCP) method to identify HLA-B*15 subtypes of groups I and II. Eighty samples of DNA carrying HLA-B*15 from 300 healthy unrelated individuals were tested. B*1502 (52.5%) and B*1525 (13.8%) were the most common subtypes found in NET. They also showed strong linkage disequilibrium with HLA-Cw and heterogeneity of HLA-A, DR, DQ haplotypes. Although limited conclusions can be drawn from this study because of the small number of DNA references used, the baseline data will be useful in the selection of common HLA-B*15 alleles when subtyping for unrelated donor transplantations.