Duchenne Muscular Dystrophy (DMD) is a severe, progressive neuromuscular genetic disease that affects approximately one in every 3,500 – 6,000 males births worldwide. DMD occurs when a mutation in the dystrophin gene prevents the cell from making a functional dystrophin protein. The role of dystrophin is crucial to the structural and membrane stability of muscle fibers in the skeletal, diaphragm and heart muscle. Absence or low levels of dystrophin in boys and men with DMD causes excessive damage to muscle cells during the normal activity of contraction and stretching, and they are eventually replaced by connective tissue and fat, resulting in a progressive loss of function.
DMD is generally diagnosed between 2 and 5 years of age when symptoms such as motor developmental delay (including difficulty in walking, climbing stairs and the use of the Gower’s Maneuver to stand from the floor) and calf muscle pseudohypertrophy become apparent. Muscle degeneration leads to loss of ambulation at 8–14 years, and progressively affects higher limbs, neck muscle and other areas. Premature death occurs at 20–30 years due to respiratory and cardiac complications.
Bushby, K., R. Finkel, D. J. Birnkrant, L. E. Case, P. R. Clemens, L. Cripe, A. Kaul, K. Kinnett, C. McDonald, S. Pandya, J. Poysky, F. Shapiro, J. Tomezsko and C. Constantin (2010). "Diagnosis and management of Duchenne muscular dystrophy, part 1: diagnosis, and pharmacological and psychosocial management." The Lancet Neurology 9(1): 77-93. And "Diagnosis and management of Duchenne muscular dystrophy, part 2: implementation of multidisciplinary care." Lancet Neurol 9(2): 177-189.