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Dating the primigenial C4-CYP21 duplication in primates
Y Horiuchi1, H Kawaguchi, F Figueroa
1Max-Planck-Institut für Biologie, Abteilung Immungenetik, Tübingen, Germany.
Genetics
|May 1, 1993
Summary
The C4 and CYP21 gene duplication in the major histocompatibility complex (Mhc) occurred over 23 million years ago via nonhomologous recombination. Subsequent homologous crossing over has homogenized these gene sequences within species.
Area of Science:
- Genetics
- Evolutionary Biology
- Immunology
Background:
- The C4 and CYP21 genes are functionally distinct but adjacent within the mammalian major histocompatibility complex (Mhc).
- These genes exist in multiple copies, arranged in C4-CYP21 modules, and are involved in complement and steroid hormone pathways, respectively.
Purpose of the Study:
- To investigate the evolutionary history and duplication mechanisms of C4-CYP21 gene clusters.
- To identify duplication breakpoints and compare sequence similarities across primate species.
Main Methods:
- Sequencing of flanking and intermodular regions of C4-CYP21 gene pairs in chimpanzees, gorillas, orangutans, and pigtail macaques.
- Sequence alignment to identify duplication breakpoints and compare sequence homology.
Main Results:
- Duplication breakpoints were conserved across the studied primate species, including humans.
- Sequences flanking paralogous C4-CYP21 genes within a species were more similar than those flanking orthologous genes across species.
- Evidence suggests the initial duplication event occurred before the divergence of apes and Old World monkeys.
Conclusions:
- The C4-CYP21 gene duplication originated via nonhomologous recombination over 23 million years ago.
- Homologous crossing over has since led to homogenization of C4-CYP21 haplotypes within species, driving expansion and contraction cycles.