Duchenne muscular dystrophy (DMD), followed by Becker muscular dystrophy (BMD) and the relatively new phenotype DMD associated dilated cardiomyopathy (DCM) are among the most recognized of a group of X-linked muscle disorders called dystropinopathies. They also include other conditions caused by dystrophin mutations, such as X-linked cardiomyopathy and isolated quadriceps myopathy.