Progressive retinal atrophy (JPH2-PRA)

Canine progressive retinal atrophies (PRA) are genetically heterogeneous diseases characterized by retinal degeneration and subsequent blindness. While there are PRA mutations that are shared by multiple breeds, many seem to be private to a single breed or are found in breeds sharing similar ancestral backgrounds. Typical signs found by ophthalmoscopic examination are widespread tapetal hyper-reflectivity and retinal vascular attenuation. Genetic testing complements clinical eye examinations with the advantage of detecting known PRA mutations before breeding age or before clinical signs present. In the breed Shih Tzu, a genetic variant in the JPH2 (junctophilin) gene has been found that might be associated with PRA. Members of the junctophilin family of proteins are responsible for maintaining subcellular architecture and regulation calcium-handling proteins in a variety of neuronal networks. The onset of PRA signs in the affected dogs was reported by owners at 5-9 years of age.