In the midbrain of PD mice, we found considerably greater levels of Lac, Ace, Cho, GABA, Myo, Cre, and reduced levels of Ala, Tau, Glu, and Gln in the midbrain of PD mice, while the disturbing levels of metabolites were changed to normal after FGF21 treatment (Figure 3; Table S1). The gene discussed is FGF21; the disease is Parkinson disease.