Resistance to gastrointestinal nematodes has previously been shown to be a moderately heritable trait in some breeds of sheep, but the mechanisms of resistance are not well understood. Selection for resistance currently relies upon faecal egg counts (FEC), blood packed cell volumes and FAMACHA visual indicator scores of anaemia. Identifying genomic markers associated with disease resistance would potentially improve the selection process and provide a more reliable means of classifying and understanding the biology behind resistant and susceptible sheep. A GWAS was conducted to identify possible genetic loci associated with resistance to Haemonchus contortus in Katahdin sheep. Forty animals were selected from the top and bottom 10% of estimated breeding values for FEC from a total pool of 641 sires and ram lambs. Samples were genotyped using Applied Biosystems™ Axiom™ Ovine Genotyping Array (50K) consisting of 51 572 SNPs. Following quality control, 46 268 SNPs were included in subsequent analyses. Analyses were conducted using a linear regression model in plink v1.90 and a single‐locus mixed model in snp and variation suite. Genome‐wide significance was determined by a Bonferroni correction for multiple testing. Using linear regression, loci on chromosomes 2, 3, 16, 23 and 24 were significantly associated at the genome level with FEC estimated breeding values, and we identified a region on chromosome 2 that was significant using both statistical analyses. We suggest a potential role for the gene DIS3L2 for gastrointestinal nematode resistance in Katahdin sheep, although further research is needed to validate these findings.

中文翻译：

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全基因组关联研究，以确定与卡塔赫丁羊胃肠道线虫抗性相关的遗传基因座

先前已证明对某些种类的绵羊对胃肠线虫具有抗性，这是一种适度可遗传的性状，但抗性的机理尚不十分清楚。目前，抗药性的选择取决于粪便卵数（FEC），血细胞填充量和贫血的FAMACHA视觉指标。鉴定与疾病抗性相关的基因组标记可能会改善选择过程，并为分类和理解抗性和易感羊的生物学特性提供更​​可靠的方法。进行了GWAS鉴定，以确定可能与对捻转血矛线虫的抗性相关的遗传基因座在Katahdin羊中。从总共641头公羊和公羊羔的FEC估计繁殖值的前10％和后10％中选择了40只动物。使用Applied Biosystems™Axiom™绵羊基因分型阵列（50K）对样品进行基因分型，该阵列由51572个SNP组成。经过质量控制，随后的分析中包括46 268个SNP。使用plink v1.90中的线性回归模型和snp和variant suite中的单位混合模型进行分析。全基因组意义由多重测试的Bonferroni校正确定。使用线性回归，第2、3、16、23和24号染色体上的基因座在基因组水平上与FEC估计的育种值显着相关，并且通过两次统计分析，我们确定了2号染色体上的重要区域。我们建议基因DIS3L2在Katahdin绵羊的胃肠道线虫抗性中具有潜在作用，尽管需要进一步的研究来验证这些发现。