PRPH2 and retinitis pigmentosa: Yet, mutations in ROM1 typically cause digenic retinitis pigmentosa in conjunction with mutations in PRPH2 (Kajiwara et al., 1994; Dryja et al., 1997), except for a handful of reports of mutations in ROM1 in patients without accompanying PRPH2 mutations (Bascom et al., 1995; Sakuma et al., 1995; Reig et al., 2000).