The Distribution and Significance of IDH Mutations in Gliomas

In 2009, the discovery of isocitrate dehydrogenase (IDH) mutations in gliomas is a powerful example of understanding of the relationship between tumor genetics and human diseases. IDHs, catalyze the oxidative decarboxylation of isocitrate to α-ketoglutarate with production of NADH/NADPH, is the key enzymes in the Krebs cycle. IDH mutations, which occur early in gliomagenesis, change the function of the enzymes, causing them to produce 2–hydroxyglutarate, and to not create NADPH. Gliomas with mutated IDH have improved prediction of patient outcomes compared to its with wild-type IDH. Thus, the WHO Classification of Tumors of the Central Nervous System was revised in 2016 to incorporate molecular biomarkers (including the IDH mutations) – together with classic histological features – in an integrated diagnosis, in order to define distinct glioma entities as precisely as possible. The aim of this chapter is to review the findings on the epidemiology and significance of IDH mutations in human gliomas, from discovery to the current knowledge about their molecular pathogenesis.