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Home / Equine Research Bank / Anim Genet / Genetic investigation of equine recurrent uveitis in Appaloo...
Animal genetics2019; 51(1); 111-116; doi: 10.1111/age.12883

Genetic investigation of equine recurrent uveitis in Appaloosa horses.

Abstract: Equine recurrent uveitis (ERU) is characterized by intraocular inflammation that often leads to blindness in horses. Appaloosas are more likely than any other breed to develop insidious ERU, distinguished by low-grade chronic intraocular inflammation, suggesting a genetic predisposition. Appaloosas are known for their white coat spotting patterns caused by the leopard complex spotting allele (LP) and the modifier PATN1. A marker linked to LP on ECA1 and markers near MHC on ECA20 were previously associated with increased ERU risk. This study aims to further investigate these loci and identify additional genetic risk factors. A GWAS was performed using the Illumina Equine SNP70 BeadChip in 91 horses. Additive mixed model approaches were used to correct for relatedness. Although they do not reach a strict Bonferroni genome-wide significance threshold, two SNPs on ECA1 and one SNP each on ECA12 and ECA29 were among the highest ranking SNPs and thus warranted further analysis (P = 1.20 × 10-5 , P = 5.91 × 10-6 , P = 4.91 × 10-5 , P = 6.46 × 10-5 ). In a second cohort (n = 98), only an association with the LP allele on ECA1 was replicated (P = 5.33 × 10-5 ). Modeling disease risk with LP, age and additional depigmentation factors (PATN1 genotype and extent of roaning) supports an additive role for LP and suggests an additive role for PATN1. Genotyping for LP and PATN1 may help predict ERU risk (AUC = 0.83). The functional role of LP and PATN1 in ERU development requires further investigation. Testing samples across breeds with leopard complex spotting patterns and a denser set of markers is warranted to further refine the genetic components of ERU.
© 2019 Stichting International Foundation for Animal Genetics.
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Publication Date: 2019-12-02 PubMed ID: 31793009DOI: 10.1111/age.12883Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This research paper is a genetic study that focuses on equine recurrent uveitis (ERU), a common cause of blindness in horses, particularly prevalent in Appaloosa horses. The study aimed to find a link between ERU and specific genes associated with the breed’s unique coat pattern.

Introduction to Equine Recurrent Uveitis and Genetics

  • Equine Recurrent Uveitis (ERU) is a disease that causes repeated inflammation in the eyes and can lead to blindness in horses.
  • The Appaloosa breed is more susceptible to ERU, suggesting a possible genetic predisposition. These horses are notable for their distinctive white coat spotting patterns, as a result of the leopard complex spotting allele (LP) and the PATN1 modifier.
  • Previous studies have linked an increase in ERU risk to a genetic marker related to LP on Equine Chromosome 1 (ECA1), and markers close to the Major Histocompatibility Complex (MHC) on ECA20.

Genome-Wide Association Study and Results

  • The study performed a Genome-Wide Association Study (GWAS) using the Illumina Equine SNP70 BeadChip on 91 horses. GWAS is a technique that helps identify genes associated with diseases.
  • The approach used was an additive mixed model to account for relatedness between horses.
  • Four Single Nucleotide Polymorphisms (SNPs) from ECA1, ECA12, and ECA29 were found to be associated with ERU. These are small genetic changes or variations that occur in the DNA sequence.
  • A second cohort of 98 horses validated the association of ERU with the LP allele on ECA1.
  • The study proposes the additive role of LP gene and potential additive role of PATN1 in ERU risk.

Implications and Future Studies

  • Genotyping for LP and PATN1 could help predict ERU risk and could be a helpful tool for horse breeders and veterinarians. The Area Under the Curve (AUC) of 0.83 suggests strong predictive power of these genetic markers.
  • However, the actual functional role of LP and PATN1 in the development of ERU requires further research.
  • The authors suggest further cross-breed studies on the leopard complex spotting patterns and a more detailed set of markers to better understand the genetic aspects of ERU.

Cite This Article

APA
Rockwell H, Mack M, Famula T, Sandmeyer L, Bauer B, Dwyer A, Lassaline M, Beeson S, Archer S, McCue M, Bellone RR. (2019). Genetic investigation of equine recurrent uveitis in Appaloosa horses. Anim Genet, 51(1), 111-116. https://doi.org/10.1111/age.12883

Publication

Animal genetics
ISSN: 1365-2052
NlmUniqueID: 8605704
Country: England
Language: English
Volume: 51
Issue: 1
Pages: 111-116

Researcher Affiliations

Rockwell, H
  • Veterinary Genetics Laboratory, Department of Population Health and Reproduction, School of Veterinary Medicine, University of California - Davis, Davis, 95616, CA, USA.
Mack, M
  • Veterinary Genetics Laboratory, Department of Population Health and Reproduction, School of Veterinary Medicine, University of California - Davis, Davis, 95616, CA, USA.
Famula, T
  • Appaloosa Project, Davis, 95616, CA, USA.
Sandmeyer, L
  • Department of Small Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, S7N 5B4, Canada.
Bauer, B
  • Department of Small Animal Clinical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, SK, S7N 5B4, Canada.
Dwyer, A
  • Genesee Valley Equine Clinic, LLC, Scottsville, NY, 14546, USA.
Lassaline, M
  • Department of Radiological and Surgical Sciences, School of Veterinary Medicine, University of California - Davis, Davis, CA, 95616, USA.
Beeson, S
  • Veterinary Population Medicine Department, College of Veterinary Medicine, University of Minnesota, St Paul, MN, 55108, USA.
Archer, S
  • Appaloosa Project, Sayward, V0P 1R0, BC, Canada.
McCue, M
  • Veterinary Population Medicine Department, College of Veterinary Medicine, University of Minnesota, St Paul, MN, 55108, USA.
Bellone, R R
  • Veterinary Genetics Laboratory, Department of Population Health and Reproduction, School of Veterinary Medicine, University of California - Davis, Davis, 95616, CA, USA.

MeSH Terms

  • Alleles
  • Animals
  • Breeding
  • Case-Control Studies
  • Genetic Association Studies / veterinary
  • Genetic Predisposition to Disease
  • Genotype
  • Hair Color
  • Horse Diseases / genetics
  • Horses / genetics
  • Models, Genetic
  • Polymorphism, Single Nucleotide
  • TRPM Cation Channels / genetics
  • Uveitis / genetics
  • Uveitis / veterinary

Grant Funding

  • F30 OD023369 / NIH HHS
  • D16EQ-028 / Morris Animal Foundation
  • Townsend Equine Health Research Fund (TEHRF)

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Citations

This article has been cited 9 times.
  1. Kirmse L, Thieme K, Doherr MG, Eule JC. Evaluation of Laboratory Techniques for the Diagnosis of Leptospira-Associated Equine Recurrent Uveitis (ERU) With Focus on the Goldmann-Witmer Coefficient. Vet Ophthalmol 2026 Jan;29(1):e70132.
    doi: 10.1111/vop.70132pubmed: 41518147google scholar: lookup
  2. Kingsley NB, Sandmeyer L, Dwyer A, Langefeld CD, McMullen RJ Jr, McCue M, Lassaline M, Bellone RR. A genome-wide investigation of insidious uveitis in Appaloosa horses. BMC Genomics 2025 Oct 9;26(1):904.
    doi: 10.1186/s12864-025-12099-3pubmed: 41068571google scholar: lookup
  3. Obradovic NA, McFadden A, Martin K, Vierra M, McLoone K, Martin E, Thomas A, Everts RE, Brooks SA, Lafayette C. Three Novel KIT Polymorphisms Found in Horses with White Coat Color Phenotypes. Animals (Basel) 2025 Mar 22;15(7).
    doi: 10.3390/ani15070915pubmed: 40218308google scholar: lookup
  4. 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).
    doi: 10.3390/ani14121802pubmed: 38929421google scholar: lookup
  5. 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).
    doi: 10.3390/ani14030451pubmed: 38338094google scholar: lookup
  6. Cassano JM, Leonard BC, Martins BC, Vapniarsky N, Morgan JT, Dow SW, Wotman KL, Pezzanite LM. Preliminary evaluation of safety and migration of immune activated mesenchymal stromal cells administered by subconjunctival injection for equine recurrent uveitis. Front Vet Sci 2023;10:1293199.
    doi: 10.3389/fvets.2023.1293199pubmed: 38162475google scholar: lookup
  7. Avila F, Hughes SS, Magdesian KG, Penedo MCT, Bellone RR. Breed Distribution and Allele Frequencies of Base Coat Color, Dilution, and White Patterning Variants across 28 Horse Breeds. Genes (Basel) 2022 Sep 13;13(9).
    doi: 10.3390/genes13091641pubmed: 36140807google scholar: lookup
  8. Wollanke B, Gerhards H, Ackermann K. Infectious Uveitis in Horses and New Insights in Its Leptospiral Biofilm-Related Pathogenesis. Microorganisms 2022 Feb 7;10(2).
    doi: 10.3390/microorganisms10020387pubmed: 35208842google scholar: lookup
  9. Geiger T, Gerhards H, Wollanke B. Detection of Anti-LipL32 Antibodies in Serum Samples from Horses with Chronic Intraocular Infection with Leptospira spp. Pathogens 2021 Oct 14;10(10).
    doi: 10.3390/pathogens10101325pubmed: 34684272google scholar: lookup
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