P.4.10 Exon skipping as a therapeutic strategy applied to a RyR1 mutation causing severe core myopathy

Central Core Disease is a myopathy resulting generally from a mutation in the RYR1 gene, encoding the skeletal muscle calcium release channel RyR1. No treatment is currently available for this disease. We studied a pathological situation in which an affected child harbors two recessive mutations, resulting in a massive reduction in the RyR1 amount. The paternal mutation inducing the inclusion of a new in frame exon in the mRNA of RyR1, resulted in the insertion of additional amino-acids and destabilization of the protein. We hypothesized that inducing the skipping of this exon would be sufficient to restore RyR1 expression and normalization of calcium releases. We developed U7-AON lentiviral vectors to induce exon-skipping on affected primary muscle cells. The efficiency of the exon skipping at the mRNA level, at the protein level and at the functional level using calcium imaging were evaluated. We observed in these affected primary muscle culture a reduction in the inclusion of the additional exon, an increase in the RyR1 protein expression, and a restoration of normal calcium releases. This study is the first demonstration of the potential of exon skipping for the therapy of Central Core Disease, from the molecular to the functional level.