Amongst the leading causes of retinal dystro­phies world­wide is Retini­tis pigmen­tosa, a severe disease often caused by splice variants in the USH2A gene. This project aims to develop a safe CRISPR-based thera­peu­tic strat­egy for correc­tion of such splic­ing defects. Using enhanced-deletion nucle­ases, the disease-causing alter­ations can be elimi­nated, hereby restor­ing  correct protein synthe­sis. The focus lies on safety features as well as the devel­op­ment of an inducible viral deliv­ery system for clini­cal application.

Retini­tis pigmen­tosa (RP) is one of the leading forms of inher­ited retinal dystro­phies, causing progres­sive vision loss in 1.5 million individ­u­als world­wide. Mutations in the USH2A gene are amongst the most frequent genetic bases for this disease and can moreover cause Usher syndrome, a combi­na­tion of Retini­tis pigmen­tosa with hearing loss. Around 10% of these patho­genic genetic variants are splic­ing mutations which disrupt mRNA matura­tion, result­ing in non-functional USH2A protein.

The PhD project aims for the preclin­i­cal devel­op­ment of a safe thera­peu­tic strat­egy for splic­ing restora­tion in USH2A. This is to be achieved using novel enhanced-deletion CRISPR — endonu­cle­ase systems. These nucle­ases can be programmed to elimi­nate the disease-causing intronic DNA sequence, leading to correctly spliced mRNA and functional protein in the target cells. The focus of the project lies firstly on improv­ing and demon­strat­ing the safety of the systems compared to conven­tional CRISPR approaches in differ­ent human cellu­lar models. Further­more, as this is trans­la­tional research, aimed at eventu­ally benefit­ing patients directly, it will also strongly concen­trate on devel­op­ing a suitable deliv­ery system for clini­cal use. Specif­i­cally, an effec­tive and inducible deliv­ery system based on adeno-associ­ated viruses shall be devel­oped to make it applic­a­ble to patient’s eyes.