Effect of gene conversion on polymorphic patterns at major histocompatibility complex loci
Author: Ohta, Tomoko
Source: Immunological Reviews, Volume 167, Number 1, February 1999 , pp. 319-325(7)
The pattern of polymorphisms at MHC loci was studied by computer simulations and by DNA sequence analyses, with special reference to synonymous and non-synonymous divergence among alleles. A model of overdominance plus short-term selection was simulated for a gene family with allelic and non-allelic gene conversion. It was found that the ratio of non-synonymous-to-synonymous divergence among alleles decreases as the non-allelic conversion becomes more frequent. On the other hand, the ratio of synonymous divergence at the antigen recognition site to that at non-coding region increases by non-allelic: conversion. By comparing such a pattern with the observed values of mammalian genes, it is suggested that non-allelic conversion is less frequent in human genes than in genes of other mammals. A quantitative analysis on the patchwork pattern was attempted by using identity excess among nucleotide sites of a gene. Comparison of simulation results with DNA data analysis shows that the rate of allelic conversion is high.
Document Type: Research Article
Affiliations: Department of Population Genetics National Institute of Genetics
Publication date: 1999-02-01