An Independent Locus Upstream of ASIP Controls Variation in the Shade of the Bay Coat Colour in Horses.
Abstract: Novel coat colour phenotypes often emerge during domestication, and there is strong evidence of genetic selection for the two main genes that control base coat colour in horses- and . These genes direct the type of pigment produced, red pheomelanin () or black eumelanin (), as well as the relative concentration and the temporal-spatial distribution of melanin pigment deposits in the skin and hair coat. Here, we describe a genome-wide association study (GWAS) to identify novel genic regions involved in the determination of the shade of bay. In total, 126 horses from five different breeds were ranked according to the extent of the distribution of eumelanin: spanning variation in phenotype from black colour restricted only to the extremities to the presence of some black pigment across nearly all the body surface. We identified a single region associated with the shade of bay ranking spanning approximately 0.5 MB on ECA22, just upstream of the gene ( 9.76 × 10). This candidate region encompasses the distal 5' end of the transcript (as predicted from other species) as well as the gene. Both loci are viable candidates based on the presence of similar alleles in other species. These results contribute to the growing understanding of coat colour genetics in the horse and to the mapping of genetic determinants of pigmentation on a molecular level. Given pleiotropic phenotypes in behaviour and obesity for alleles, especially those in the 5' regulatory region, improved understanding of this new allele may have implications for health management in the horse.
Publication Date: 2020-05-30 PubMed ID: 32486210PubMed Central: PMC7349280DOI: 10.3390/genes11060606Google Scholar: Lookup
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Summary
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The research article discusses a study that explored genetic factors determining the shades of bay coat colour in horses. A specific locus found upstream of the ASIP gene was identified as an influence on this variation.
Study Overview
- The study involved a genome-wide association study (GWAS) to identify new gene regions involved in determining different shades of bay coat color in horses. This was motivated by observations that coat color often changes during domestication, with clear signs of genetic selection for primary genes that control base coat color in horses.
- Two main genes direct pigment type—red pheomelanin (PMEL) or black eumelanin (ASIP)—and control relative concentration known as the MC1R gene, as well as the temporal-spatial distribution of melanin pigment deposits in the skin and hair coat.
- The participating sample included 126 horses from five separate breeds. These horses were ranked based on the extent of eumelanin distribution, with phenotype variations ranging from pure black restricted to extremities to some black pigment present across nearly the entire body surface.
Key Findings
- The researchers identified a single region linked with the shade of bay color. It spans approximately 0.5 MB on ECA22, located just upstream of the ASIP gene.
- This candidate region overlaps the predicted distal 5′ end of the MC1R transcript and the ZNF804 gene. Both these gene sites are considered viable candidates based on similarity of alleles present in other species.
Contribution and Implications
- The findings of this study contribute to an improved understanding of coat color genetics in horses and help to map pigmentation determinants on a molecular level.
- As the ASIP alleles have been linked to varying phenotypes in behaviour and obesity, particularly those in the 5′ regulatory region, a better comprehension of this new ASIP allele could have potential implications in managing horse health in the future.
Cite This Article
APA
Corbin LJ, Pope J, Sanson J, Antczak DF, Miller D, Sadeghi R, Brooks SA.
(2020).
An Independent Locus Upstream of ASIP Controls Variation in the Shade of the Bay Coat Colour in Horses.
Genes (Basel), 11(6), 606.
https://doi.org/10.3390/genes11060606 Publication
Researcher Affiliations
- Population Health Sciences, Bristol Medical School, University of Bristol, Bristol BS8 2BN, UK.
- MRC Integrative Epidemiology Unit at University of Bristol, Bristol BS8 2BN, UK.
- Bristol Veterinary School, University of Bristol, Bristol BS8 1QU, UK.
- Department of Animal Sciences, University of Florida, Gainesville, FL 32610, USA.
- Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
- Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
- Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
- Department of Animal Sciences, University of Florida, Gainesville, FL 32610, USA.
- UF Genetics Institute, University of Florida, Gainesville, FL 32611, USA.
MeSH Terms
- Agouti Signaling Protein / genetics
- Alleles
- Animals
- Breeding
- Color
- Hair Color / genetics
- Horses / genetics
- Melanins / biosynthesis
- Melanins / genetics
- Receptor, Melanocortin, Type 1 / genetics
Grant Funding
- MC_UU_00011 / Medical Research Council
Conflict of Interest Statement
The authors declare no conflict of interest.
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