Progressive Retinal Atrophy (PRA) is the most common type of inherited retinal dystrophies experienced by dogs. PRA is an outer retinal disease affecting the photoreceptors and the pigment epithelium of the eyes, causing a progressive loss of vision, eventuating in blindness.The retinal condition is recessively inherited through an autosomal gene in all breeds except for the Siberian husky and the Samoyed, in which PRA is a sex-linked trait, due to mutations in the RPGR gene. PRA in dogs is comparative to Retinitis Pigmentosa (RP) in humans, which displays similar clinical characteristics.
At present, there is still no treatment for PRA, however, thanks to the fairly recently assembled canine genome sequence, researchers have been able to identify and locate the mutated genes responsible for retinal degradation. This breakthrough has enabled them to use gene therapy to restore the vision of PRA affected experimental dogs, in which a corrective genetic substance is used to target these mutations/defects. While, gene therapy may sound like a clear winner, it does not actually restore the already damaged parts of the retina, but stops the advancement of PRA, possibly protecting the undamaged photoreceptors.
While this technique of gene therapy is still a work in progress for PRA; clearly alarm bells are ringing as to the immense benefits that would arise from discovering how to cure this condition. It would not only hold benefits for dogs but also across species, namely to the closely related condition in humans.
Rebecca Martens
Primary Resource:
Narstrom, K & Ofri, R 2006, 'Light at the end of the tunnel? Advances in the understanding and treatment of glaucoma and inherited retinal degeneration', The Veterinary Journal, vol. 174, no. 1, pp. 10-22.
Seconday resources:
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