Evolution of DQw2-Related Haplotypes.

摘要

The majority of HLA-DR alleles have been grouped into two families on the basis of supertypicserologic specificities, DRw52 and DRw53. Although members of each family share a common evolutionary pathway, there is evidence that the DRw52 and DRw53 pathways have crossed producing haplotypes that express genes found in both families. Haplotypes that share DQw2-like alpha genes are an example of this convergence. The haplotypes in this group include DRw52-associated DR3 (DQw2 and DQw4), DR5 (DQw3), DRw8 (DQw4), and DRw- (DQw2); and DRw53-associated DR7 (DQw2 and DQw3) and DRw9 (DQw2). Some of these haplotypes share the DQw2 serologic specificity whereas others share only a DQw2-like alpha gene. A unique DQB2 Hinc II DNA restriction fragment is found associated with many of these haplotypes. Reciprocal recombination, mutation, and gene conversion play a major role in the generation of diversity in these haplotypes. We have recently described the structural basis of the DRw18(3)-associated DQw4 molecule. Keywords: Human leukocyte antigens; Reprints. (kt)