DMD and Duchenne muscular dystrophy: Duchenne muscular dystrophy (DMD) is an X-linked genetic disorder affecting approximately 1 in 5,050 male births.1 DMD is caused by pathogenic variants of the DMD gene, leading to a lack of dystrophin, an essential protein for maintaining the cell membranes of muscle fibers.2 The lack of dystrophin causes ongoing myofiber degeneration and regeneration, progressive fibrotic replacement of skeletal muscle, loss of motor function and ambulation, and early death.