FGF21 has been recently described to drive the integrated mitochondrial stress response and activate a cascade of events in mitochondrial myopathy patients and mice, thus leading to a distinct metabolic remodelling (von Holstein‐Rathlou et al, 2016; Lehtonen et al, 2016; AlJohani et al, 2019; Forsstrom et al, 2019). Here, FGF21 is linked to Mitochondrial myopathy.