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New discovery will be important to fully understand vision and possible repair.

The study, led by researchers at the Ottawa Hospital Research Institute (OHRI), was first conceived to better understand how a specific gene, know as Scn8a, controls electrical impulses in nerves. But scientists did not expected to find an entirely new function for this well known gene. The research, published in tomorrow's edition of Journal of Neuroscience, is the first indication that the Scn8a gene has a role in the function and development of photoreceptors - the first cells in the eye to detect light in the retina of the eye and send signals to the brain (instrumental to vision.) "The way this is happening is baffling," noted Dr. Patrice Cote, the lead author of the study and a senior postdoctoral fellow in the laboratory of Dr. Rashmi Kothary at the OHRI. "It just goes to show how complex and intricate the entire vision process is and how much we still need to explore to fully understand its entire functioning." Researchers studied mice lacking the Scn8a gene, using an electroretinogram (which could be likened to an electrocardiogram) and discovered that in addition to suffering from paralysis, the mice were also blind. By ruling out virtually all other possibilities, the scientists further determined that the Scn8a gene was responsible for the blindness, although they could not definitively establish how one contributed to the other. Dr. Cote explained that the gene, which is normally expressed in the brain, is clearly necessary for the function of the photoreceptors. "In the case of the missing gene, we believe that a problem arises during development when other cells are unable to transmit signals to the photoreceptors," he said, adding that more study will be necessary. The next step will be to determine exactly what role the gene plays in vision. That might be possible by removing the gene from the retina exclusively and seeing - when the mouse matures - if the retina is degenerating. Dr. Kothary, the senior author on the study who is also a professor at the University of Ottawa, stated: "we are quite excited by this finding. It represents a first step in uncovering a novel pathway in retinal development and should provide insight into the establishment of vision." For ophthalmologists, the discovery is encouraging. "This is really excellent research," noted Dr. Bruce Jackson, Director of the University of Ottawa Eye Institute. "The more we can understand about how the retina develops, the better chance we have of finding a cure for macular degeneration and other blinding retinal diseases." The study grouped seven researchers from Ottawa as well as France and the U.S., and was funded by the Muscular Dystrophy Association. Media contact: Nathalie Trepanier Communications Manager OHRI 613-798-5555 ext. 19691

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