title: Genome-wide association study using high-density single nucleotide polymorphism arrays and whole-genome sequences for clinical mastitis traits in dairy cattle.
abstract: Mastitis is a mammary disease that frequently affects dairy cattle. Despite considerable research on the development of effective prevention and treatment strategies, mastitis continues to be a significant issue in bovine veterinary medicine. To identify major genes that affect mastitis in dairy cattle, 6 chromosomal regions on Bos taurus autosome (BTA) 6, 13, 16, 19, and 20 were selected from a genome scan for 9 mastitis phenotypes using imputed high-density single nucleotide polymorphism arrays. Association analyses using sequence-level variants for the 6 targeted regions were carried out to map causal variants using whole-genome sequence data from 3 breeds. The quantitative trait loci (QTL) discovery population comprised 4,992 progeny-tested Holstein bulls, and QTL were confirmed in 4,442 Nordic Red and 1,126 Jersey cattle. The targeted regions were imputed to the sequence level. The highest association signal for clinical mastitis was observed on BTA 6 at 88.97 Mb in Holstein cattle and was confirmed in Nordic Red cattle. The peak association region on BTA 6 contained 2 genes: vitamin D-binding protein precursor (GC) and neuropeptide FF receptor 2 (NPFFR2), which, based on known biological functions, are good candidates for affecting mastitis. However, strong linkage disequilibrium in this region prevented conclusive determination of the causal gene. A different QTL on BTA 6 located at 88.32 Mb in Holstein cattle affected mastitis. In addition, QTL on BTA 13 and 19 were confirmed to segregate in Nordic Red cattle and QTL on BTA 16 and 20 were confirmed in Jersey cattle. Although several candidate genes were identified in these targeted regions, it was not possible to identify a gene or polymorphism as the causal factor for any of these regions.
authors.affiliation: Center for Quantitative Genetics and Genomics, Department of Molecular Biology and Genetics, Aarhus University, 8830 Tjele, Denmark. Electronic address: Goutam.Sahana@agrsci.dk.
authors.forename: G
authors.initials: G
authors.lastname: Sahana
authors.affiliation: Center for Quantitative Genetics and Genomics, Department of Molecular Biology and Genetics, Aarhus University, 8830 Tjele, Denmark.
authors.forename: B
authors.initials: B
authors.lastname: Guldbrandtsen
authors.affiliation: Molecular Genetics and Systems Biology, Department of Molecular Biology and Genetics, Aarhus University, 8830 Tjele, Denmark.
authors.forename: B
authors.initials: B
authors.lastname: Thomsen
authors.affiliation: Molecular Genetics and Systems Biology, Department of Molecular Biology and Genetics, Aarhus University, 8830 Tjele, Denmark.
authors.forename: L-E
authors.initials: LE
authors.lastname: Holm
authors.affiliation: Molecular Genetics and Systems Biology, Department of Molecular Biology and Genetics, Aarhus University, 8830 Tjele, Denmark.
authors.forename: F
authors.initials: F
authors.lastname: Panitz
authors.affiliation: Center for Quantitative Genetics and Genomics, Department of Molecular Biology and Genetics, Aarhus University, 8830 Tjele, Denmark.
authors.forename: R F
authors.initials: RF
authors.lastname: Brøndum
authors.affiliation: Molecular Genetics and Systems Biology, Department of Molecular Biology and Genetics, Aarhus University, 8830 Tjele, Denmark.
authors.forename: C
authors.initials: C
authors.lastname: Bendixen
authors.affiliation: Center for Quantitative Genetics and Genomics, Department of Molecular Biology and Genetics, Aarhus University, 8830 Tjele, Denmark.
authors.forename: M S
authors.initials: MS
authors.lastname: Lund
mesh_terms: D000818:Animals; D002417:Cattle; D005260:Female; D020022:Genetic Predisposition to Disease; D055106:Genome-Wide Association Study; D015810:Linkage Disequilibrium; D008297:Male; D008414:Mastitis, Bovine / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D040641:Quantitative Trait Loci
keywords: NGS; dairy cattle; mastitis; quantitative trait locus