Keywords: 2KG, 2-ketoglutarate; D-2HG, d-2-hydroxyglutarate; D-2HGDH, d-2-hydroxyglutarate dehydrogenase; D-LDH, d-lactate dehydrogenase; ETF, electron transfer flavoprotein; ETFQO, electron-transfer flavoprotein:ubiquinone oxidoreductase; L-2HG, l-2-hydroxyglutara