Toward a Gene Therapy for Dominant Disease: Validation of an RNA Interference-Based Mutation-Independent Approach

The intragenic heterogeneity encountered in many dominant disease-causing genes represents a significant challenge with respect to development of economically viable therapeutics. For example, 25% of autosomal dominant retinitis pigmentosa is caused by over 100 different mutations within the gene encoding rhodopsin, each of which could require a unique gene therapy. We describe here an RNA interference (RNAi)-based mutation-independent approach, targeting as an example murine rhodopsin. Native transcripts are suppressed by a single RNAi molecular species, whereas transcripts from replacement genes engineered at degenerate third-codon wobble positions are resistant to suppression. We demonstrate suppression of murine rhodopsin transcript by up to 90% with full concomitant expression of replacement transcript and establish the validity of this approach in cell culture, retinal explants, and mouse liver in vivo.