About 10 years ago, the identification of point mutations in the isocitrate dehydrogenase (IDH) 1 (cytosolic) and 2 (mitochondrial) genes [36], provided a further level of classification and, importantly, helped to discriminate between primary (IDH1 wild-type, IDH1wt) and secondary (IDH1 mutated, IDH1mut) GBM. This evidence concerns the gene IDH1 and glioblastoma.