The majority (50–86%) of gliomas diagnosed in younger adults (<45 years old) have recurrent somatic mutations in one of the genes encoding isocitrate dehydrogenase (IDH1 and IDH2) leading to the overproduction of 2-hydroxyglutarate, an oncometabolite that plays a key role in malignant transformation and is interestingly detectable in vivo by 1H-MRS [85,86]. The gene discussed is IDH3A; the disease is glioma.