PRPH2 and retinitis pigmentosa: Despite a clear causal association between some eye diseases and mutations in specific genes (CORD2 for cone-rod distrophy type 2, PRPH2 for CACD, as reinforced in this research; rhodopsin (RHO) for retinitis pigmentosa), mutations in the same gene could lead to different degrees of disease severity and mutations in different genes may lead to similar phenotypes.