As peroxisome-proliferator-activated receptor-γ coactivator-1 (PGC-1α) is a principal factor regulating slow-twitch fiber determination, muscle-specific overexpression of PGC-1α improves the parameters characteristic of Duchenne muscular dystrophy (DMD), a regulatory mechanism mediated by folliculin interacting protein-1 (Fnip 1) (Handschin et al., 2007; Reyes et al., 2015). The gene discussed is PPARGC1A; the disease is Duchenne muscular dystrophy.