An A to G change at position 2726 (c.2726C>G) resulting in a proline to arginine substitution at amino acid 909 (p.P909R) was introduced in exon 21 and an FRT-flanked neomycin selection cassette was also inserted. The neomycin selection cassette was removed via flp-mediated recombination. This mutation corresponds to the human c.2747C>G, p.P916R mutation causing congenital dyserythropoietic anemia type III. Mice were screened for the Crb1 c.3841delC mutation known as a cause of retinal dystrophy and do not contain this mutation. (J:321429)