Abstract
BackgroundSeveral 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).ResultsOphthalmic 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.ConclusionHaving 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.
Highlights
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
We investigated the possibility of the molecular cause of this PRA being a known mutation, by carrying out the genetic tests for XLPRA1 and XLPRA2
Clinical features of PRA in the Border Collie In total, 487 dogs were examined by the same veterinary ophthalmologist
Summary
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. Progressive Retinal Atrophy (PRA) has been described in more than 100 breeds of dog [1,2,3], providing a powerful resource for the identification of new retinopathy-causing genes and a unique model for treatments for homologous human retinal diseases [4,5]. The strong founder effect and genetic drift occurring during the breeding of dogs may have significantly reduced the genetic heterogeneity of diseases in each breed, making it easier to identify causal mutations in dogs than in humans.
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