There is no significant association between the localisation or the type of RDH5 mutation with the severity of the disease phenotype (including electrophysiological observations or the presence/absence of cone dystrophy) (Sato et al. 2004; Niwa et al. 2005; Sergouniotis et al. 2011; Pras et al. 2012). Here, RDH5 is linked to cone dystrophy.