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Directional and balancing selection in human beta-defensins.

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journal contribution
posted on 24.10.2012, 08:59 by Edward J. Hollox, John AL Armour
Background:In primates, infection is an important force driving gene evolution, and this is reflected in the importance of infectious disease in human morbidity today. The beta-defensins are key components of the innate immune system, with antimicrobial and cell signalling roles, but also reproductive functions. Here we examine evolution of beta-defensins in catarrhine primates and variation within different human populations. Results:We show that five beta-defensin genes that do not show copy number variation in humans show evidence of positive selection in catarrhine primates, and identify specific codons that have been under selective pressure. Direct haplotyping of DEFB127 in humans suggests long-term balancing selection: there are two highly diverged haplotype clades carrying different variants of a codon that, in primates, is positively selected. For DEFB132, we show that extensive diversity, including a four-state amino acid polymorphism (valine, isoleucine, alanine and threonine at position 93), is present in hunter-gatherer populations, both African and non-African, but not found in samples from agricultural populations. Conclusion:Some, but not all, beta-defensin genes show positive selection in catarrhine primates. There is suggestive evidence of different selective pressures on these genes in humans, but the nature of the selective pressure remains unclear and is likely to differ between populations.

History

Citation

BMC Evolutionary Biology 2008, 8:113

Version

VoR (Version of Record)

Published in

BMC Evolutionary Biology 2008

Publisher

BioMed Central Ltd

eissn

1471-2148

Copyright date

2008

Available date

24/10/2012

Publisher version

http://www.biomedcentral.com/1471-2148/8/113

Language

eng