While female carrier mice expressing around 50% of the normal levels of dystrophin in a mosaic manner were unaffected10, low dystrophin levels were associated to an alleviated (cardiac) DMD-like phenotype in mdx and dystrophin/utrophin double-knockout mice expressing full-length murine dystrophin in a mosaic manner12,62. The gene discussed is DMD; the disease is Duchenne muscular dystrophy.