Defining Endpoints in Becker Muscular Dystrophy

Becker Muscular Dystrophy (BMD) is most frequently due to in-frame mutations in the dystrophin gene that are associated with reduced levels of frequently shortened dystrophin, though other mutations may be related to the Becker phenotype. There is wide variation in the age of onset and degree of progression, ranging from childhood to late adulthood. The more severe form of dystrophinopathy, Duchenne muscular dystrophy, has a more characteristic rate of progression and overall natural history. The wide variation in severity of progression has led to challenges in the design and conduct of approaching therapeutic trials. There is a need for a more rigorous natural history study to assist in the design of these promising therapeutic trials.