FGF21 and Duchenne muscular dystrophy: Mitochondrial deficiency (Timpani et al., 2015), autophage dysfunction (De Palma et al., 2012), and endoplasmic reticulum (ER) stressors (Pauly et al., 2017) have been implicated as part of the pathogenesis of DMD and have also been shown to increase the expression of FGF21 from skeletal muscle (Zhou et al., 2018; Li et al., 2020).