RPE65 and retinal degeneration: RPE65 is expressed in retinal epithelial cells and encodes a retinoid isomerohydrolase as part of the visual cycle for the recycling of the chromophore 11-cis retinal.1 2 The phenotype of retinal dystrophies caused by bi-allelic RPE65 mutations is typically an early onset retinal degeneration (EORD) or Leber congenital amaurosis type 2 (LCA2).3–5