IDH3A and neoplasm: However, IDH1 mutations have been demonstrated to be subclonal in 20 % of GBMs [41], levels of amino acids, glutathione metabolites, choline derivatives, and TCA cycle intermediates were altered in mutant IDH1- and IDH2-expressing cells, and mutated IDH1-R132H enzyme can dominant-negatively inhibit IDH1-WT isocitrate dehydrogenase activity, meaning that the extent of metabolic heterogeneity may be influenced by the dominance of IDH1 mutations within the tumour hierarchy.