RP9 and retinitis pigmentosa 1: In particular, mutations in four RNA splicing factor genes underlie some autosomal dominant forms of RP, namely RP9 (RP9, OMIM 607331 [3]), RP11 (PRPF31, OMIM 600138 [4]), RP13 (PRPF8, OMIM 600059 [5]), and RP18 (PRPF3, OMIM 607301 [6]).