Diversity and diversification of HLA-A,B,C alleles.

摘要: The nucleotide sequences encoding 14 HLA-A,B,C and 5 ChLA-A,B,C molecules have been determined. Combining these with published data has enabled the polymorphism in 40 9 alleles to be analyzed. Diversity is generated through assortment of point mutations by recombinational mechanisms including gene allelic conversions. distribution frequency silent replacement substitutions indicate that there positive selection for diversity 5' part (exons 1 3) homogenization locus specificity 3' 4 8). These differences may correlate lengths converted two parts CpG dinucleotide. Locus-specific divergence HLA-A,B, C demonstrates events involving a more important than conversion between loci. This contrasts predominance evolution mutants H-2Kb gene. However, striking example HLA-B an oriental haplotype found. Comparison human chimpanzee reveals extensive sharing polymorphisms, confirming diversification slow process, much contemporary originated ancestral primate species before emergence Homo sapiens. There less at HLA-A compared HLA-B, greater similarity also being seen ChLA-A ChLA-B alleles. Although "variable" exons HLA-A, increased heterogeneity "conserved" HLA-B.