W132 Evaluation of Mhc as a Genetic Risk Factor for Chorioretinitis and Retinal Atrophy in the Flat-Coated Retriever

Date: Sunday, January 15, 2012
Time: 10:20 AM
Room: Royal Palm Salon 5-6
Tomas Bergström , Dept. of Animal Breeding and Genetics, Uppsala, Sweden
Maria Wilbe , Dept. of Animal Breeding and Genetics, Uppsala, Sweden
Ana Letícia Kolicheski , Dept. of Animal Breeding and Genetics, Uppsala, Sweden
Merina Shrestha , Dept. of Animal Breeding and Genetics, Uppsala, Sweden
Björn Ekesten , Department of Clinical Sciences, Uppsala
Göran Andersson , Dept. of Animal Breeding and Genetics, Uppsala, Sweden
Kristina Narfström , Veterinary Ophthalmology College of Veterinary Medicine & Mason Eye Institute, Columbia, MO
In recent years approximately 20 FCRs have been diagnosed with PRA or retinopathy in Sweden and in the Netherlands. However, the phenotype was atypical for classical PRA. The dogs had some remaining vision even in advanced cases, uni- or bilateral multiple chorioretinal scarring, persistence of variable electroretinographic responses and, (morphologically) severe retinal fibrosis. A majority of the affected dogs also showed clinical signs of inflammation in the retina (chorioretinitis). One of the dogs with unilateral active retinitis as well as signs of chorioretinitis, was subjected to autopsy. Signs of visceral larvae migrans (Toxocara canis) were found with lesions in kidneys and lungs. Several studies have shown that Mhc genotypes are associated with protection or increased risk of inflammatory disease, including chorioretinitis in humans, upon exposure to different parasites. A major selective force to maintain high degree of Mhc polymorphism is considered to be parasite-driven. Thus, development of chorioretinitis in FCRs could be associated with Mhc, which in dogs is called Dog Leukocyte Antigens (DLA). To investigate such potential genetic association a pilot study of DLA class II association to chorioretinitis among FCRs has been initiated. Current results indicate that homozygosity of the DLA class II haplotype  “DLA-DRB1*01501/ -DQA1*00601/-DQB1*02301” is increased among dogs with chorioretinopathy and may thus increase the risk for development of this disease. To conclude that Mhc is a genetic risk factor for this form of retinal degeneration requires analysis of DLA class II in a larger case-control population and results from such a study will be reported.