The presence and distribution of genetic alterations in brain tumors, such as alterations in PI3K, PDGFR, PTEN, TP53, IDH, EGFR, H3F3A, ATRX and TERT (33–35), are now a criteria used to differentiate glioma subtypes (28, 36, 37). The gene discussed is IDH1; the disease is glioma.