GPNMB and retinal degeneration: For example, a spontaneous mutation in Gpnmb, a gene that contributes to pigmentary-related eye diseases, is known to have been fixed in the DBA/2J stock (Libby et al., 2005; Lu et al., 2011) and an in-frame deletion in centrosomal/ciliary protein Cep290 that produces retinal degeneration was fixed in BXD24 (Chang et al., 2006).