Drogemuller, C. | bioRxiv Science

bioRxiv2024

Genome-Wide Association Testing for Haemorrhagic Bowel Syndrome in a Swiss Large White Pig Population

BackgroundThe porcine haemorrhagic bowel syndrome (HBS) is a multifactorial disease causing fatal gastrointestinal disturbances and sudden death in fattening pigs. HBS is the leading cause of deaths during fattening in Swiss pigs, with unclear etiology. Environmental and management factors are associated with HBS incidence, but recent findings also suggest a potential genetic predisposition. Pigs sired by a Swiss Large White (SLW) line appear more prone to HBS. Here we conduct genome-wide association studies (GWAS) for HBS between cases and controls to investigate potential genetic factors for the disease in Swiss fattening pigs. ResultsOur study included 1,036 HBS cases and 4,080 controls with available microarray genotypes or whole-genome sequencing data. Variant positions were determined according to the current porcine reference assembly (Sscrofa11.1) or a HiFi-based SLW haplotype assembly which we constructed using trio-binning. GWAS for HBS were conducted using 12.49 to 15.46 million biallelic variants in three mapping cohorts consisting of purebred animals from SLW sire and dam lines, or crosses between these two parental lines. The statistical model applied for the GWAS accounted for animal relatedness, population structure, and an imbalanced case/control ratio. No sequence variants significantly associated with HBS were identified, regardless of the cohort analysed and the reference sequence considered. ConclusionsThe lack of genetic associations despite a relatively large sample size suggests that susceptibility to HBS in the studied SLW population is not due to large effect variants but may be influenced by numerous small effect genetic variants, in addition to environmental and management factors.

genomics↗

bioRxiv2020

Dog color patterns explained by modular promoters of ancient canid origin

Distinctive color patterns in dogs are an integral component of canine diversity. Color pattern differences are thought to have arisen from mutation and artificial selection during and after domestication from wolves 1,2 but important gaps remain in understanding how these patterns evolved and are genetically controlled 3,4. In other mammals, variation at the ASIP gene controls both the temporal and spatial distribution of yellow and black pigments 3,5-7. Here we identify independent regulatory modules for ventral and hair cycle ASIP expression, and we characterize their action and evolutionary origin. Structural variants define multiple alleles for each regulatory module and are combined in different ways to explain five distinctive dog color patterns. Phylogenetic analysis reveals that the haplotype combination for one of these patterns is shared with arctic white wolves and that its hair cycle-specific module likely originated from an extinct canid that diverged from grey wolves more than 2 million years before present. Natural selection for a lighter coat during the Pleistocene provided the genetic framework for widespread color variation in dogs and wolves.

genetics↗