Our animals had a similar rate of retinal degeneration than the albino Abca4−∕− mice (Fig. 1C) and rosette formation was only found in one 12-month-old animal from a total of 25 Abca4−∕−.Rdh8−∕− animals examined light-microscopically up to an age of 25 months. This evidence concerns the gene ABCA4 and retinal degeneration.