PDE6B and retinitis pigmentosa 1: Proof-of-principle studies using RNAi-based approaches to knock down mutant transcripts have also been evaluated in mice for the treatment IRD associated with Prph2, Impdh1 (RP10), Guca1a (cone-rod dystrophy), and Pde6b (RP) with varying levels of success (Tam et al., 2008; Tosi et al., 2011; Petrs-Silva et al., 2012; Jiang et al., 2013).