IDH1 and central nervous system cancer: While IDH should produce alpha-ketoglutarate from the oxidative decarboxylation of isocitrate, the mutant enzyme results in aberrantly elevated production of the D enantiomer of 2-HG from alpha-ketoglutarate reduction.3 As the main enantiomer produced by the IDH mutation, overabundant D-2-HG has profound epigenetic effects4 and reprograms the glioma metabolome,5 increasing intracellular oxidative stress.