Evolution in HLA-DRB1 and major histocompatibility complex class II haplotypes of Australian aborigines. Definition of a new DRB1 allele and distribution of DRB1 gene frequencies.

The distribution of HLA-DRB1 alleles was studied in Australian aborigines from different parts of Australia. There were significant differences in the frequencies of DRB10412, 1409, and 1410 between the Central Desert and Yuendumu populations and the previously reported Cape York and Kimberley aboriginal populations. A new DRB1 allele, DRB11414, present at low frequency in the Central Desert population, was identified. DRB11414 appears to be closely related to DRB11407 and is proposed to have arisen by intragenic recombination. A novel DR-DQ haplotype, DRB11402-DRB30101-DQA10501-DQB10402, was also identified. This haplotype may be ancestral to the DRB11409-DQB10402 haplotype present in these populations. The presence of alleles and haplotypes apparently confined to Australian aboriginal populations and differences in the distribution of these alleles in different populations suggests that evolution has occurred in the class II region in the period since colonization of Australia, an estimated 50,000 years ago.