Progressive Retinal Atrophy in the Border Collie: A new XLPRA
1 IGDR CNRS, Génétique et Développement, Faculté de Médecine, Université de Rennes1, 35043 Rennes Cedex, France
2 Clinique vétérinaire, 2 Place Beaulieu F-63400 Chamalières, France
3 INSERM U535, Génétique Epidémiologique et Structures des Populations Humaines, Hopital Paul Brousse, Villejuif, France
4 Antagene, Immeuble Le Meltem, 2 Allée des Séquoias F-69760 Limonest, France
BMC Veterinary Research 2008, 4:10 doi:10.1186/1746-6148-4-10Published: 3 March 2008
Several forms of progressive retinal atrophy (PRA) segregate in more than 100 breeds of dog with each PRA segregating in one or a few breeds. This breed specificity may be accounted for by founder effects and genetic drift, which have reduced the genetic heterogeneity of each breed, thereby facilitating the identification of causal mutations. We report here a new form of PRA segregating in the Border Collie breed. The clinical signs, including the loss of night vision and a progressive loss of day vision, resulting in complete blindness, occur at the age of three to four years and may be detected earlier through systematic ocular fundus examination and electroretinography (ERG).
Ophthalmic examinations performed on 487 dogs showed that affected dogs present a classical form of PRA. Of those, 274 have been sampled for DNA extraction and 87 could be connected through a large pedigree. Segregation analysis suggested an X-linked mode of transmission; therefore both XLPRA1 and XLPRA2 mutations were excluded through the genetic tests.
Having excluded these mutations, we suggest that this PRA segregating in Border Collie is a new XLPRA (XLPRA3) and propose it as a potential model for the homologous human disease, X-Linked Retinitis Pigmentosa.