OR10

The Ryanodine Receptor Type 1 (RyR1) is a calcium channel that plays a pivotal role in the contraction of skeletal muscle cells. Several mutations in the gene encoding this channel have been identified as causative factors in a group of rare myopathies, collectively referred to as "RyR1-related myopathies." These conditions manifest as muscle weakness of varying degrees of severity in affected individuals with no cure available. One of the primary challenges in developing gene therapy for these conditions is the extensive number of mutations found in the RYR1 gene, as well as their widespread distribution throughout the gene. In addition, gene replacement therapy is not a viable option for RYR1 due to its large size. In light of these challenges, we propose a versatile approach aimed at rectifying RyR1 calcium release, irrespective of the specific patient mutation. Our methodology involves the targeted deletion of the pathogenic allele, enabled by the use of CRISPR-Cas9 technology. For the proof-of-principle, we focused on a dominant mutation identified in a French family afflicted with Central Core Disease. Our approach entailed the design of a pipeline to select the most effective guide RNAs for targeting the pathogenic allele. Subsequently, we transduced immortalized myoblasts derived from the patient using lentiviruses expressing both Cas9 and the selected guide RNA. Throughout the course of our study, we assessed the efficacy of the treatment at the DNA, RNA, and functional levels. Our findings represent the first successful application of genome editing techniques for the treatment of RyR1-related myopathies.