Tackling the itch: GWAS-based candidate genes for psoroptic mange sensitivity in Belgian Blue cattle

Belgian Blue cattle suffer from an extreme sensitivity for infection by the Psoroptes ovis mite, causing an itchy, crusty dermatitis with economical and animal welfare consequences. Interbreed differences suggest mange sensitivity is heritable, while the intrabreed differences open perspectives for genetic selection as a sustainable solution. Our study is the first attempt to unravel the genetic background of psoroptic mange sensitivity. Six-hundred-and-seventy Belgian Blue animals were phenotyped based on lesion extent, lesion appearance, and mite counts, measured at three consecutive farm visits. Collected blood samples were then genotyped with the Illumina Bovine SNP50 v2 BeadChip. A haplotype based association analysis (GLASCOW) of the animals with extreme phenotypes showed a suggestive signal at the telomere of chromosome 11, with the most prevalent haplotype cluster having a substantial impact on the phenotype. A 1.3 Mb region of interest could be delineated after imputation and consequent bootstrapping of the region around the peak. Due to the intergenic location of the associated markers, a candidate gene is presented based on its location in the specific region and its relationship with other parasitic diseases. In addition, the possible role of collagens and lipocalins is described, illustrating the need for future research that can eventually lead to a genetic selection program for more mange resistant Belgian Blue.