PHILADELPHIA - Veterinary ophthalmology researchers from the University of Pennsylvania have used gene therapy to restore retinal cone function and day vision in two canine models of congenital achromatopsia, also called rod monochromacy or total color blindness.
Achromatopsia is a rare autosomal recessive disorder with an estimated prevalence in human beings of about 1 in 30,000 to 50,000. It primarily affects the function of the cone photoreceptors in the retina and serves as a representative model for other more common inherited retinal disorders affecting cones. Cone function is essential for color vision, central visual acuity and most daily visual activities, which underlines the importance of the newly developed treatment.
The treatment cured younger canines regardless of the mutation that caused their achromatopsia. It was effective for the 33 months of the study and most likely is permanent; however, researchers also observed a reproducible reduction in the cone therapy success rate in dogs treated at 54 weeks of age or older.
The successful therapy in dogs was documented by the restoration of the cone function using electroretinography and by objective measure of day vision behavior. The behavioral results suggest that inner retinal cells and central visual pathways were able to usefully process the input from the recovered cones.
The results represent the second successful cone-directed gene replacement therapy in achromatopsia animal models and the first outside of mouse models. The gene therapy targets mutations of the CNGB3 gene, the most common cause of achromatopsia in humans. Achromatopsia-affected dogs represent the only natural large animal model of CNGB3-achromatopsia.
The results hold promise for future clinical trials of cone-directed gene therapy in achromatopsia and other cone-specific disorders.
"The successful restoration of visual function with recombinant adeno-associated viru
|Contact: Jordan Reese|
University of Pennsylvania