OGDH and Parkinson disease: A mitochondrial proteome analysis demonstrated downregulation in the pyruvate dehydrogenase complex (PDH), TCA cycle (IDH3A, isocitrate dehydrogenase; aconitase; CS, citrate synthase; OGDH, 2 oxoglutarate dehydrogenase or αKGDH, α-ketoglutarate dehydrogenase (Figure 1), mitochondrial complexes I, II, III, and IV activity, and fatty acid catabolism in regions with mild and severe pathology (substantia nigra, late frontal cortex, and putamen of early/late PD) [73].