DMD and Duchenne muscular dystrophy: To generate a murine model lacking both dystrophin and utrophin, the utrophin gene (Utrn) was deleted from the C57BL/10ScSn mdx mouse, and although these mdx/utrn−/− or dko mice are no longer genetically similar to patients with DMD, their phenotype more closely resembles the disease progression in patients (Deconinck et al., 1998).