Around 200 mutations in the rhodopsin gene (RHO) cause retinal diseases, in most patients in the form of retinitis pigmentosa (RP) [2,3,4,5], although other phenotypes have also been described, including sector RP [6], pericentral RP [7], congenital stationary night blindness (CSNB) [1,2,3,4,5], and retinitis punctata albescens [8]. The gene discussed is RHO; the disease is congenital stationary night blindness.