IDH1 and glioblastoma: While 2HG is produced by other enzymes including hydroxyacid-oxoacid transhydrogenase (80), human phosphoglycerate dehydrogenase (81), lactate dehydrogenase (82), and l-malate dehydrogenase (83), it is believed that IDH1/2 mutations are almost exclusively what drive 2HG overaccumulation in low-grade glioma and secondary glioblastoma.