[Genetic Diagnosis and Molecular Therapies for Duchenne Muscular Dystrophy]

Duchenne muscular dystrophy (DMD) is the most common form of inherited muscle disease and is characterized by progressive muscle wasting, ultimately resulting in the death of patients in their twenties or thirties. DMD is characterized by a deficiency of the muscle dystrophin as a result of mutations in the dystrophin gene. Currently, no effective treatment for DMD is available. Promising molecular therapies which are mutation-specific have been developed. Transformation of an out-of-frame mRNA into an in-frame dystrophin message by inducing exon skipping is considered one of the approaches most likely to lead to success. We demonstrated that the intravenous administration of the antisense oligonucleotide against the splicing enhancer sequence results in exon skipping and production of the dystrophin protein in DMD case for the first time. After extensive studies, anti-sense oligonucleotides comprising different monomers have undergone clinical trials and provided favorable results, enabling improvements in ambulation of DMD patients. Induction of the read-through of nonsense mutations is expected to produce dystrophin in DMD patients with nonsense mutations, which are detected in 19% of DMD cases. The clinical effectiveness of gentamicin and PTC124 has been reported. We have demonstrated that arbekacin-mediated read-through can markedly ameliorate muscular dystrophy in vitro. We have already begun a clinical trial of nonsense mutation read-through therapy using arbekacin. Some of these drug candidates are planned to undergo submission for approval to regulatory agencies in the US and EU. We hope that these molecular therapies will contribute towards DMD treatment.