CRB1 and Doyne honeycomb retinal dystrophy: COL2A1, WDPCP and HMX1 are linked with syndromic and systemic retinopathy and autosomal dominant or recessive retinal degeneration; CRB1 is linked to early onset Leber congenital amaurosis (LCA8), and a severe form of autosomal recessive retinitis pigmentosa (RP12); and EFEMP1 mutations affect RPE cells and are associated with both Malattia Leventinese and Doyne honeycomb retinal dystrophy.