Dystrophinopathy is caused by mutations in the dystrophin gene, which lead to progressive muscle degeneration, necrosis, and finally death. Recently, golden retrievers have been suggested as a useful animal model for studying human dystrophinopathy, but the model has limitations due to difficulty in maintaining the genetic background using conventional breeding. In this study, we successfully generated a dystrophin mutant dog using the CRISPR/Cas9 system and somatic cell nuclear transfer. The

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... strophin mutant dog displayed typical phenotypes, such as elevated serum creatine kinase, dystrophin deficiency, skeletal muscle defects, an abnormal ECG, and avoidance of ambulation, all of which are consistent with human dystrophinopathy. These results indicate that dystrophin mutant dogs can be a reliable and effective animal model for preclinical studies into new therapies for human dystrophinopathy.