The double-knockout Crb1Crb2Chx10Cre mouse (which lacks both Crb1 and Crb2 in retinal progenitor cells) develops LCA; the double-knockout Crb1+/−Crb2Chx10Cre mouse (which lacks one allele of Crb1 and both alleles of Crb2 in retinal progenitor cells) also develops LCA (Pellissier et al., 2013). Here, CRB2 is linked to Leber congenital amaurosis.