Researchers, based at the University of Washington, Seattle, Washington, Généthon, France, Boston Children's Hospital in Massachusetts, and Virginia Polytechnic Institute and State University (Virginia Tech) in Blacksburg, Virginia, conducted the study. The scientists found that both mice and dogs responded from a single intravascular injection of AAV, produced at Généthon, with robust improvement in muscle strength, corrected muscle structure at the microscopic level, and prolonged life. No toxic or immune response was observed in the dogs.
These results demonstrate the efficacy of gene replacement therapy for myotubular myopathy in animal models and pave the way to a clinical trial in patients.
Children born with X-linked myotubular myopathy, which affects about 1 in 50,000 male births, have very weak skeletal muscles, causing them to appear floppy, with severe respiratory difficulties. Survival beyond birth requires intensive support, often including tube feeding and mechanical ventilation, but effective therapy is not available for patients, and most die in childhood.