Mice genetically manipulated for opsin are protected from diabetes-induced increase in ROS and increase in proinflammatory molecules in the retina, suggesting an important role in the development of DR.25 Mutation of proline on position 23 in rhodopsin induces rhodopsin misfolding and photoreceptor degeneration; the data showed that diabetic mice with this proline mutation substituted with histidine (P23H) and are therefore protected from retinal capillary degeneration, further strengthening the role of photoreceptors in DR. The gene discussed is RHO; the disease is diabetes mellitus.