Recent studies have highlighted the salutary effects of FGF21 as a stress-responsive hormone on systemic metabolic homeostasis and, particularly, as a sensitive signal for mitochondrial defects manifesting in muscular and neurological diseases.5–13 These findings position FGF21 as a plausible candidate regulator for optimizing energy allocation and ensuring cardiac energy priority. This evidence concerns the gene FGF21 and nervous system disorder.