Molecular characterization of point mutations in dystrophin gene and drug-induced readthroughs of stop codons

Abstract

Duchenne Muscular Dystrophy (DMD) is an inherited paediatric disorder caused by mutations in the gene encoding the muscle protein, dystrophin. A novel approach for gene repair in DMD targets suppression of nonsense mutations thus resulting in translational readthrough and restoration of dystrophin expression. The main objectives of this study are to: (1) screen for point mutations in six non-deletion DMD patients, (2) investigate the efficacy of four aminoglycosides (gentamicin, paromomycin, tobramycin and G418) in mediating dystrophin translational readthrough of the three types of stop codons, and (3) establish a cell-free protein assay and develop a novel cell-based assay as platforms for studying dystrophin translational readthroughs. Results demonstrate that all the aminoglycosides used in this study could restore dystrophin expression for both assay systems. However, therapeutic readthrough levels, which corresponded to a range between 10% and 40% of the wild-type protein expression, where obtained only in the cell-free protein assay system.