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MHC class II haplotypes and linkage disequilibrium in primates
1Department of Medical Genetics, University of Uppsala, Sweden.
Human Immunology
|January 1, 1993
Summary
Major histocompatibility complex (MHC) class II genes show high polymorphism. Human populations exhibit strong linkage disequilibrium in these genes, a pattern not conserved in chimpanzees or gorillas due to extensive recombination.
Area of Science:
- Evolutionary genetics
- Immunogenetics
- Primate genomics
Background:
- Major histocompatibility complex (MHC) class II loci (DR, DQ, DP) are highly polymorphic.
- Strong linkage disequilibrium exists between these loci in humans.
- Evolutionary conservation of this disequilibrium across primate species is unknown.
Purpose of the Study:
- To investigate the evolutionary conservation of linkage disequilibrium in MHC class II loci.
- To compare patterns of disequilibrium in humans, chimpanzees, and gorillas.
Main Methods:
- Sequencing and oligonucleotide hybridization of PCR-amplified DNA.
- Analysis of DQA1, DQB1, and DRB1-6 loci in chimpanzee and gorilla.
- Identification of novel DRB sequences.
Main Results:
- DRB locus distribution differs between human and nonhuman primate haplotypes.
- Strong linkage disequilibrium observed in humans (DQA1-DQB1, DQ-DRB1) was absent in nonhuman hominoids.
- Extensive recombination within and between DR and DQ regions since species divergence.
Conclusions:
- Haplotype similarity between human and nonhuman primates is low due to significant recombination.
- Human-specific strong linkage disequilibrium may result from recombination barriers, founder effects, or selection.