DMD and muscular dystrophy: It was shown in mdx mouse model that dystrophin-utrophin double mutants developed more severe muscle weakness than dystrophin-only mutants and that the overexpression of utrophin appeared to prevent the development of muscular dystrophy signs, suggesting that utrophin upregulation could be used as a strategy to treat DMD (Deconinck et al., 1997; Grady et al., 1997; Tinsley et al., 1998).