Association between single nucleotide polymorphisms in the CXCR1 gene and somatic cell score in Holstein dairy cattle

In addition to its position in a quantitative trait locus for somatic cell score (SCS) and its function in the immune response, the CXCR1 chemokine receptor gene located on Bos taurus autosome 2 is an auspicious candidate gene for udder health in dairy cattle. An association analysis was conducted in the German Holstein-Friesian population to test the association between the single nucleotide polymorphism (SNP) at position +777 within the CXCR1 gene and the SNP at position −1768 in the 5′ upstream region of this gene (rs41255711) and the indicator trait SCS by using a granddaughter design. Data were analyzed for 3 families, with a total of 749 genotyped bulls and an extended pedigree of 8,071 animals from the national German bovine genome mapping project. Variance component estimation was used to determine the source of phenotypic variation in the chromosomal area of interest. A 20-cM window surrounding the 2 SNP in the CXCR1 gene was examined. Although the percentage of variance caused by the putative quantitative trait locus in the area studied was relatively large (12 and 11%, respectively), no statistically significant association of the SNP CXCR1+777 or CXCR1−1768 with SCS was found. These results contradict previously published studies.