RP9 and retinitis pigmentosa 1: Meanwhile, due to the genetic heterogeneity of RP, patients with novel clinically diagnosed adRP should be analyzed for mutations in at least 12 common candidate genes (CA4, CRX, IMPDH1, NR2E3, RP9, PRPF3, PRPF8, PRPF31, PRPH2, RHO, RP1, and TOPORS), which contain more than 95% of the known mutations that cause adRP [7-10].