The mdx mouse has a myopathy caused by dystrophin deficiency, and is therefore
biochemically and genetically homologous to human Duchenne muscular dystrophy. While
mdx mouse muscle shows no dystrophin by immunoblotting, a very small percentage of
myofibers appear clearly dystrophin-positive by immunofluorescence microscopy. We have
characterized these rare positive-staining fibers, and conclude that they are indeed
expressing dystrophin despite a nonsense mutation within the dystrophin gene. Thus, the …