PRPF8 and retinitis pigmentosa 1: Pre-mRNA processing factors (PRPFs), including the large highly conserved scaffolding protein PRPF8 and its interacting RNA helicase Brr2, form part of the U4/U6.U5 tri-snRNP subunit of the spliceosome and, collectively, are mutated as a frequent cause of autosomal dominant retinitis pigmentosa (RP)3–7.