IDH1 and glioma: About 10% GBM patients harbor IDH1/2 mutation and have a history of lower-grade glioma, which is defined as secondary GBM.1,12,13 The Cancer Genome Atlas (TCGA) project have unveiled comprehensive genetic and transcriptomic profiles of GBM through next-generation sequencing,14 which classifies GBM into four molecular subtypes: Proneural, Neural, Mesenchymal, and Classical.15