PRPF8 and retinitis pigmentosa 1: Recently, it was reported that RP mutations in PRPF3 and PRPF8 exert dominant-negative activity in knock-in mice (Prpf3+/T494M and Prpf8+/H2309P) and induce degenerative processes that however surprisingly are found in the retinal pigment epithelium and not photoreceptors [8].