For example, mdx mice, a widely used mouse model of Duchenne muscular dystrophy (DMD), have much milder pathology as compared with DMD patients20; the severity of muscular dystrophy in dysferlin-null mice depends on their genetic background21; a common disease-associated missense mutation in α-sarcoglycan fails to cause muscular dystrophy in mice22. Here, DYSF is linked to Duchenne muscular dystrophy.