Identification of W13 in the American Miniature Horse and Shetland Pony Populations.
Abstract: Coat color is a trait of economic significance in horses. Variants in seven genes have been documented to cause white patterning in horses. Of the 34 variants that have been identified in KIT proto-oncogene, receptor tyrosine kinase (), 27 have only been reported in a single individual or family and thus not all are routinely offered for genetic testing. Therefore, to enable proper use of marker-assisted selection, determining breed specificity for these alleles is warranted. Screening 19 unregistered all-white Shetland ponies for 16 white patterning markers identified 14 individuals whose phenotype could not be explained by testing results. In evaluating other known dominant white variants, 14 horses were heterozygous for W13. W13 was previously only reported in two quarter horses and a family of Australian miniature horses. Genotyping known white spotting variants in 30 owner-reported white animals (25 Miniature Horses and five Shetland ponies) identified two additional American Miniature Horses. The estimated allele frequency of W13 in the American Miniature Horse was 0.0063 (79 , 1 ) and the allele was not detected in a random sample ( = 59) of Shetland ponies. No homozygous W13 individuals were identified and ponies had a similar all-white coat with pink skin phenotype, regardless of the other white spotting variants present, demonstrating that W13 results in a Mendelian inherited dominant white phenotype and homozygosity is likely lethal. These findings document the presence of W13 in the American Miniature Horse and Shetland pony populations at a low frequency and illustrate the importance of testing for this variant in additional breeds.
Publication Date: 2021-12-14 PubMed ID: 34946933PubMed Central: PMC8702037DOI: 10.3390/genes12121985Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research discusses the identification of a specific variant linked to white coat color in horses, named W13, predominantly in American Miniature Horses and Shetland Ponies. The results showed the W13 variant has a dominant white phenotype and is likely lethal when homozygous.
Objective of the Research
The research aimed at identifying the breed specificity of the 34 genetic variants causing white patterning in horses. Among these, W13 variant was found to cause white coloration in horse coats. The identification of breed-specific alleles assists in marker-assisted selection for specific traits, like coat color.
Methodology of the Research
- The researchers screened 19 unregistered all-white Shetland ponies for 16 white patterning markers.
- They noticed that the phenotype of 14 ponies could not be explained by the testing results which urged them to evaluate other known dominant white variants.
- After evaluation, 14 horses were found to be heterozygous for W13, a variant previously only reported in two quarter horses and a family of Australian mini horses.
- To further confirm, white spotting variants were genotyped in 30 owner-reported white animals which included 25 Miniature Horses and five Shetland ponies.
Findings of the Research
- Two additional American Miniature horses were identified as having the W13 variant.
- The estimated allele frequency of W13 in the American Miniature Horse was 0.0063. The allele was not detected in a random sample of 59 Shetland ponies.
- No homozygous W13 individuals were identified, suggesting homozygosity could possibly be lethal.
- All the identified W13 individuals displayed a similar trait of all-white coat with pink skin phenotype, which indicated W13 results in a Mendelian inherited dominant white phenotype.
- The research concluded that W13 is present in American miniature Horse and Shetland Pony populations at a low frequency and underscores the need for testing this variant in additional breeds.
Cite This Article
APA
Esdaile E, Kallenberg A, Avila F, Bellone RR.
(2021).
Identification of W13 in the American Miniature Horse and Shetland Pony Populations.
Genes (Basel), 12(12), 1985.
https://doi.org/10.3390/genes12121985 Publication
Researcher Affiliations
- Veterinary Genetics Laboratory, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA.
- Veterinary Genetics Laboratory, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA.
- Veterinary Genetics Laboratory, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA.
- Veterinary Genetics Laboratory, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA.
- Department of Population Health and Reproduction, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA.
MeSH Terms
- Alleles
- Animals
- Biomarkers
- Gene Frequency / genetics
- Genetic Association Studies
- Hair Color / genetics
- Homozygote
- Horses / genetics
- Phenotype
- Pigmentation / genetics
- Proto-Oncogene Proteins c-kit / genetics
Conflict of Interest Statement
R.R.B., F.A., A.K., and E.E. are affiliated with the Veterinary Genetics Laboratory, a laboratory offering parentage and diagnostic DNA tests in horses and other species.
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Citations
This article has been cited 2 times.- Liu X, Peng Y, Zhang X, Wang X, Chen W, Kou X, Liang H, Ren W, Khan MZ, Wang C. Coloration in Equine: Overview of Candidate Genes Associated with Coat Color Phenotypes. Animals (Basel) 2024 Jun 17;14(12).
- McFadden A, Vierra M, Martin K, Brooks SA, Everts RE, Lafayette C. Spotting the Pattern: A Review on White Coat Color in the Domestic Horse. Animals (Basel) 2024 Jan 30;14(3).
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