Neuroprotective effects of metformin on PD have also been demonstrated in a large amount of animal and cellular studies through mechanisms including inhibiting α-synuclein aggregation, reversing mitochondrial dysfunction, attenuating oxidative stress, modulating autophagy, and activation of the AMP-activated protein kinase (AMPK) pathway [125,126,127]. The gene discussed is SNCA; the disease is Parkinson disease.