Interallelic recombination has not played a major role in the history of the HLA-C loons

The human major histocompatibility complex class I loci HLA-A and HLA-B have previously been shown to differ with regard to the rate of interallelic recombination, with a much higher rate being observed in the case of HLA-B. Until recently, there were very few HLA-C transcripts available for analysis. In the present study, we analyzed C locus alleles from human (n = 24), chimpanzee (n = 1), and gorilla (n = 5). Both phylogenetic analysis and a method for detecting clusters of sites indicative of recombination showed relatively little evidence of interallelic recombination. Thus, in spite of the close evolutionary relationship between HLA-C and HLA-B, HLA-C is evolving more similarly to the HLA-A locus than is HLA-B, further emphasizing the uniqueness of HLA-B.