Genomic regions underlying susceptibility to bovine tuberculosis in Holstein-Friesian cattleReport as inadecuate

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BMC Genetics

, 18:27

Complex traits and quantitative genetics


BackgroundThe significant social and economic loss as a result of bovine tuberculosis bTB presents a continuous challenge to cattle industries in the UK and worldwide. However, host genetic variation in cattle susceptibility to bTB provides an opportunity to select for resistant animals and further understand the genetic mechanisms underlying disease dynamics.

MethodsThe present study identified genomic regions associated with susceptibility to bTB using genome-wide association GWA, regional heritability mapping RHM and chromosome association approaches. Phenotypes comprised de-regressed estimated breeding values of 804 Holstein-Friesian sires and pertained to three bTB indicator traits: i positive reactors to the skin test with positive post-mortem examination results phenotype 1; ii positive reactors to the skin test regardless of post-mortem examination results phenotype 2 and iii as in ii plus non-reactors and inconclusive reactors to the skin tests with positive post-mortem examination results phenotype 3. Genotypes based on the 50 K SNP DNA array were available and a total of 34,874 SNPs remained per animal after quality control.

ResultsThe estimated polygenic heritability for susceptibility to bTB was 0.26, 0.37 and 0.34 for phenotypes 1, 2 and 3, respectively. GWA analysis identified a putative SNP on Bos taurus autosomes BTA 2 associated with phenotype 1, and another on BTA 23 associated with phenotype 2. Genomic regions encompassing these SNPs were found to harbour potentially relevant annotated genes. RHM confirmed the effect of these genomic regions and identified new regions on BTA 18 for phenotype 1 and BTA 3 for phenotypes 2 and 3. Heritabilities of the genomic regions ranged between 0.05 and 0.08 across the three phenotypes. Chromosome association analysis indicated a major role of BTA 23 on susceptibility to bTB.

ConclusionGenomic regions and candidate genes identified in the present study provide an opportunity to further understand pathways critical to cattle susceptibility to bTB and enhance genetic improvement programmes aiming at controlling and eradicating the disease.

KeywordsBovine tuberculosis Susceptibility Genome-wide association Regional heritability mapping Chromosome association AbbreviationsBTABos taurus autosome

bTBBovine tuberculosis

EBVEstimated breeding value

GWAGenome-wide association

LDLinkage disequilibrium

LRTLikelihood ratio test

QTLQuantitative trait loci

RHMRegional heritability mapping

SNPSingle neucleotide polymorphism

Electronic supplementary materialThe online version of this article doi:10.1186-s12863-017-0493-7 contains supplementary material, which is available to authorized users.

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Author: Kethusegile Raphaka - Oswald Matika - Enrique Sánchez-Molano - Raphael Mrode - Mike Peter Coffey - Valentina Riggio - Eliz


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