In particular, building on our previous findings, the present study provides two novel aspects: (i) in the context of DMD, MAO-B plays a key role in determining oxidative stress, and (ii) a novel inhibitor for this isoform significantly improves functional impairment occurring in mdx mice and can protect myotubes of DMD patients from mitochondrial dysfunction. The gene discussed is MAOB; the disease is Duchenne muscular dystrophy.