Gene therapy to treat Duchenne muscular distrophy
MD is due to a dystrophin deficiency caused by mutation of the DMD gene, located on the X chromosome. It causes muscle weakness that progressively worsens until it reaches the cardiac and respiratory muscles. The estimated incidence is 1 in 3,500/4,000 boys, and women are only exceptionally affected. Life expectancy for affected patients is 20 to 30 years, thanks to improved medical and surgical management. Current treatment options include corticosteroids, angiotensin-converting enzyme inhibitors and beta-blockers for cardiac function, physiotherapy, and spinal arthrodesis.
The first gene therapy has just received accelerated approval from the Food and Drug Administration (FDA) for children with MD aged between 4 and 5 years old. Its principle is to enable the production of a shortened version of dystrophin. Gene therapy has been shown to produce this mini-protein, but the therapy has yet to be shown to improve muscle function, a prerequisite for final FDA approval.
A clinical trial is currently underway, with results expected this autumn. The approval of a gene therapy for this disease represents a major step forward for MD, but also for other diseases of genetic origin.