IDH1 and glioma: A well-known example of altered enzyme specificity is IDH1, in whichmutating Arg132 changes the reaction from converting isocitrate toalpha-ketoglutarate to converting alpha-ketoglutarate toR(−)-2-hydroxyglutarate, which leads to glioma.60 This residue is 3.18 Å apart fromalpha-ketoglutarate (PDB id 4L06).