No evidence of prenatal diversifying selection at locus or supertype levels in the dog MHC class II lociReport as inadecuate

No evidence of prenatal diversifying selection at locus or supertype levels in the dog MHC class II loci - Download this document for free, or read online. Document in PDF available to download.

Canine Genetics and Epidemiology

, 3:9

First Online: 18 November 2016Received: 28 January 2016Accepted: 02 October 2016


BackgroundDespite decades of studying, the mechanisms maintaining high diversity in the genes of the Major Histocompatibility Complex MHC are still puzzling scientists. In addition to pathogen recognition and other functions, MHC molecules may act prenatally in mate choice and in maternal-foetal interactions. These interactions are potential selective mechanisms that increase genetic diversity in the MHC. During pregnancy, immune response has a dual role: the foetus represents foreign tissue compared to mother, but histo-incompatibility is required for successful pregnancy. We have studied the prenatal selection in MHC class II loci DLA-DQA1, DLA-DQB1 and DLA-DRB1 in domestic dogs by comparing the observed and expected offspring genotype proportions in 110 dog families. Several potential selection targets were addressed, including the peptide-binding site, the MHC locus, three-locus haplotype and supertype levels. For the supertype analysis, the first canine supertype classification was created based on in silico analysis of peptide-binding amino-acid polymorphism.

ResultsIn most loci and levels, no deviation from the expected genotype frequencies was observed. However, one peptide-binding site in DLA-DRB1 had an excess of heterozygotes among the offspring. In addition, if the father shared a DLA-DRB1 allele with the mother, that allele was inherited by the offspring more frequently than expected, suggesting the selective advantage of a histo-compatible foetus, in contrast to our expectations.

ConclusionsWe conclude that there is some evidence of post-copulatory selection at nucleotide site level in the MHC loci of pet dogs. But due to no indication of selection at locus, three-locus, or supertype levels, we estimated that the prenatal selection coefficient is less than 0.3 in domestic dogs and very likely other factors are more important in maintaining the genetic diversity in MHC loci.

KeywordsCanis familiaris MHC Prenatal selection Supertype classification Abbreviationsdfdegree of freedom

DLADog leucocyte antigen

DNADeoxyribonucleic acid

EVTExtravillous trophoblast cells

FISInbreeding coefficient

HeExpected number of heterozygotes

HLAHuman leucocyte antigen

HoObserved number of heterozygotes

LDLinkage disequilibrium

MHCMajor histocompatibility complex

NFNumber of families

NKNatural killer cells

NONumber of offspring

OROlfactory receptor

PBRPeptide-binding region

PCAPrincipal component analysis

sselection coefficient

Electronic supplementary materialThe online version of this article doi:10.1186-s40575-016-0038-9 contains supplementary material, which is available to authorized users.

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Author: Alina K. Niskanen - Lorna J. Kennedy - Hannes Lohi - Jouni Aspi - Tanja Pyhäjärvi


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