The first exon duplication mouse model of Duchenne muscular dystrophy: A tool for therapeutic development

•Exon 2 duplication is the most frequent exonic duplication associated with DMD.•We created the 1st mouse carrying an exon duplication developing muscular dystrophy.•The exon 2 duplication results in a disrupted reading frame, and minimal protein expression.•The Dup2 mouse is both pathologically and physiologically similar to mdx.•This new model will be a powerful tool for testing duplication-specific therapies.