PRPF31 and retinitis pigmentosa 1: To determine whether mutations in splicing factors associated with RP cause detectable splicing defects in non-retinal tissues, we obtained lymphoblastoid cell lines from four groups of individuals: RP patients carrying the H2309P or H2309R mutation in PRPF8; those with the R372_A375delfs mutation in PRPF31 who have severe RP; those carrying the PRPF31 R372_A375delfs PRPF31 mutation but not manifesting RP [4]; and controls (see Table 1).