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). Here, UTRN is linked to Duchenne muscular dystrophy.