Duchenne and Becker muscular dystrophies (DMD and BMD) are neuromuscular diseases characterized by progressive muscle wasting and weakness due to degeneration of skeletal, smooth and cardiac muscle. The disease or phenotype is Duchenne and Becker muscular dystrophy (EFO_0700060, an Experimental Factor Ontology identifier). Also known as: severe dystrophinopathy, Duchenne and Becker type.