Equine Multiple Congenital Ocular Anomalies (MCOA) syndrome in PMEL17 (Silver) mutant ponies: five cases.
Abstract: To describe the clinical phenotype and genetics of equine Multiple Congenital Ocular Anomalies (MCOA) syndrome in PMEL17 (Silver) mutant ponies. Methods: Five presumably unrelated ponies. Methods: The ponies were examined under field conditions in their barn by slit lamp biomicroscopy, indirect ophthalmoscopy, and applanation tonometry. Blood was collected and genomic DNA extracted for MCOA genotyping using the PMEL17ex11 marker. Results: One pony solely presented with temporal ciliary body cysts, suggestive of the less severe Cyst phenotype of MCOA; the animal was heterozygous at the MCOA locus. Multiple bilateral anterior segment anomalies were identified in four ponies, consistent with the more severe MCOA phenotype characterized by cornea globosa, iris hypoplasia, encircling granula iridica along the pupillary ruff, and cataracts. These animals were homozygous for the mutant MCOA allele. Four of the ponies had a silver dapple or chocolate coat color with white or flaxen manes and tails. Silver dappling was masked by the palomino coloring of a 5th pony that was homozygous at the MCOA locus. Conclusions: The MCOA syndrome can be seen in ponies. The results of both clinical evaluation and genotyping resembled the previously described MCOA of both Rocky Mountain and Kentucky Mountain Saddle horses.
© 2011 American College of Veterinary Ophthalmologists.
Publication Date: 2011-04-18 PubMed ID: 21929608PubMed Central: PMC3262593DOI: 10.1111/j.1463-5224.2011.00878.xGoogle Scholar: Lookup
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Summary
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This research investigates the phenotype and genetics behind Multiple Congenital Ocular Anomalies (MCOA) syndrome in PMEL17 (Silver) mutant ponies. It is based on the examination of five ponies and emphasizes that MCOA syndrome can also manifest in ponies, resembling its effects in Rocky Mountain and Kentucky Mountain Saddle horses.
Methods
- The research was carried out using five presumably unrelated ponies.
- The ponies were evaluated under their natural conditions in their barn. The researchers adopted various diagnostic methods, including slit lamp biomicroscopy – a diagnostic tool to examine the anterior segment of the eye, indirect ophthalmoscopy – an instrumental method used to examine the interior structures of the eye, and applanation tonometry – a diagnostic tool commonly used to measure the fluid pressure inside the eye.
- Blood was collected from the subjects and genomic DNA extracted in order to conduct genotyping for MCOA using the PMEL17ex11 genetic marker. This allowed the researchers to determine the genetic predisposition of MCOA in these ponies.
Results
- Among the five ponies examined, one only exhibited temporal ciliary body cysts. Such symptoms are characteristic of the less severe Cyst phenotype of MCOA. The pony had a heterozygous condition at the MCOA locus, indicating the presence of two different forms of a gene at a particular loci.
- Multiple bilateral anterior segment anomalies were found in four ponies. These anomalies were consistent with a more severe and comprehensive MCOA phenotype, including various effects like cornea globosa, iris hypoplasia, encircling granula iridica along the pupillary ruff, and cataracts. These animals were homozygous for the mutant MCOA allele, meaning they had two identical forms of a particular gene, one on each of chromosome pair.
- Four out of the five ponies had silver dapple or chocolate coats with white or flaxen manes and tails. However, the silver dappling was concealed by the palomino coloring in one pony. This pony was homozygous at the MCOA locus, having two identical alleles for a single trait.
Conclusion
- The results from this study concluded that MCOA syndrome can indeed be observed in ponies.
- The findings and their implications from both the physical evaluation and genotyping were akin to the previously recognized MCOA in Rocky Mountain and Kentucky Mountain Saddle horses.
Cite This Article
APA
Komáromy AM, Rowlan JS, La Croix NC, Mangan BG.
(2011).
Equine Multiple Congenital Ocular Anomalies (MCOA) syndrome in PMEL17 (Silver) mutant ponies: five cases.
Vet Ophthalmol, 14(5), 313-320.
https://doi.org/10.1111/j.1463-5224.2011.00878.x Publication
Researcher Affiliations
- Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA. komaromy@vet.upenn.edu
MeSH Terms
- Animals
- Eye Diseases / congenital
- Eye Diseases / genetics
- Eye Diseases / pathology
- Female
- Gene Expression Regulation
- Genotype
- Horse Diseases / genetics
- Horse Diseases / pathology
- Horses
- Male
- Mutation
- gp100 Melanoma Antigen / genetics
- gp100 Melanoma Antigen / metabolism
Grant Funding
- K12 EY015398 / NEI NIH HHS
- EY015398 / NEI NIH HHS
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