PHILADELPHIA, April 22 (UPI) -- University of Pennsylvania scientists say they have used gene therapy to restore retinal cone function and day vision in two canine models of color blindness.
The veterinary ophthalmology researchers said the disorder -- called congenital achromatopsia or rod monochromacy -- is a rare autosomal recessive genetic disorder with an estimated prevalence in human beings of about 1 in 50,000.
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 scientists said.
The treatment cured younger canines regardless of the mutation that caused their achromatopsia, the researchers said, noting the gene therapy was effective for the 33 months of the study and most likely is permanent. However, they said they observed a reproducible reduction in the cone therapy success rate in dogs treated at 54 weeks of age or older.
The results represent the second successful cone-directed gene replacement therapy in achromatopsia animal models and the first outside of mouse models.
"The successful restoration of visual function with recombinant adeno-associated virus-mediated gene replacement therapy has ushered in a new era of retinal therapeutics," said Assistant Professor Andras Komaromy, who led the study.
The research that included scientists from Temple University, the University of Florida, Cornell University and the University of Alabama is reported online in advance of publication in the journal Human Molecular Genetics.