Résumé
Inherited retinal dystrophies (IRDs) are characterized by progressive loss of vision thatleads to legal blindness, as there is currently no treatment. To date, retinal genesupplementation appears to be the most promising therapeutic strategy. However, themost currently used vector has a limited cloning capacity.For this reason, gene therapy for IRDs due to large genes is less advanced. For suchdisorders, an attractive alternative to gene replacement is genome editing. A revolution inthis domain is the bacterial CRISPR/Cas9 system, which is highly specific. This system isparticularly interesting in the case of recurrent mutations, as it could be administered to alarge number of patients hence avoiding individual personalized systems, which are costprohibitive.An interesting candidate gene for a genome-editing approach is USH2A. USH2Ais the most prevalent IRD causative gene as it is responsible for syndromic (Ushersyndrome type 2) and isolated autosomal recessive retinitis pigmentosa (arRP). However,the large size of USH2A makes gene supplementation challenging. Interestingly, tworecurrent USH2A mutations have been reported, c.2299delG and p.C759F, that collectivelyare responsible for approximately half of these cases.We combined CRISPR/Cas9 and iPSC-derived retinal organoid technology in order toprogress in the understanding of the pathophysiology of USH2A-associated RP and toevaluate the feasibility of a genome editing approach. We show the high specificity of ourCRISPR/Cas9 system and the potential of using this approach as both a tool to understandpathophysiology but also as a potential treatment option.