Interestingly, mutations in the genes coding for metabolic enzymes such as succinate dehydrogenase (SDH), fumarate hydratase (FH), isocitrate dehydrogenases 1/2 (IDH1/2) and phosphoglycerate dehydrogenase (PHGDH) have been reported in various tumors: paraganglioma [42], renal cancer [43] and glioblastoma multiforme [44,45,46]. Here, IDH1 is linked to glioblastoma.