title: Natural selection and the evolutionary history of major histocompatibility complex loci.
abstract: The major histocompatibility complex (MHC) is a multi-gene family unique to the vertebrates, whose products function to present peptides to T cells. Certain MHC loci are highly polymorphic, and this polymorphism is maintained by a form of balancing selection, probably overdominant selection. This selection has several consequences for MHC biology that make these genes different from neutrally evolving genes: an enhanced rate of nonsynonymous nucleotide substitution in codons encoding the peptide-binding region; long-lasting ("trans-species") polymorphism; and homogenization of introns relative to exons as a result of recombination and subsequent genetic drift. The MHC also reveals evidence of processes shared with other multi-gene families, including gene duplication and deletion and a low level of inter-locus recombination.
authors.affiliation: Department of Biology and Institute of Molecular Evolutionary Genetics, The Pennsylvania State University, University Park, PA 16802, USA. austin@ hugans3.bio.psu.edu
authors.forename: A L
authors.initials: AL
authors.lastname: Hughes
authors.forename: M
authors.initials: M
authors.lastname: Yeager
mesh_terms: D000818:Animals; D019143:Evolution, Molecular; D005819:Genetic Markers / Q000502:physiology*; D006801:Humans; D008285:Major Histocompatibility Complex / Q000235:genetics*; D012641:Selection, Genetic
chemical_list: D005819:Genetic Markers