ABCA4 and Retinal atrophy: Rdh8 is considered as an assistant susceptibility gene for STGD1 and dAMD, and its knockout in mice does not incite the degeneration of retina but slows the reduction of atRAL to atROL in the visual (retinoid) cycle and accelerates retinal atrophy in Abca4 mutant mice (9, 10).