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Discovery of New Form of Dystrophin Protein Could Lead to Therapy for Some DMD Patients
Scientists have discovered a new form of dystrophin, a protein critical to normal muscle function, and identified the genetic mechanism responsible for its production. Studies of the new protein isoform, published online on August 10, 2014 in Nature Medicine and led by a team in The Research Institute at Nationwide Children's Hospital, suggest it may offer a novel therapeutic approach for some patients with Duchenne muscular dystrophy, a debilitating neuromuscular condition that usually leaves patients unable to walk on their own by age 12. Duchenne muscular dystrophy, or DMD, is caused by mutations in the gene that encodes dystrophin, which plays a role in stabilizing the membrane of muscle fibers. Without sufficient quantities of the protein, muscle fibers are particularly susceptible to injury during contraction. Over time, the muscle degenerates and muscle fibers are slowly replaced by fat and scar tissue. Many different types of mutations can lead to DMD, some of which block dystrophin production altogether and others that result in a protein that doesn't function normally. In 2009, a team led by Kevin Flanigan, M.D., a principal investigator in the Center for Gene Therapy at Nationwide Children's, published two studies describing patients whose genetic mutation was located in a exon 1, at the beginning of the gene. This mutation should have made natural production of functioning dystrophin impossible, resulting in severe disease. However, the patients had only minimal symptoms and relatives carrying the same mutations were identified who were walking well into their 70s. Muscle biopsies revealed that, despite the genetic mutations, the patients were producing significant amounts of a slightly smaller yet functioning dystrophin. In the 2009 studies, Dr.