IDH1 and neoplasm: Neurofibromin, the protein product of NF1, regulates the inactivation of the Ras pathway and acts as a tumor suppressor. Recent studies have identified somatic alterations in the gene encoding for neurofibromin (NF1) in a subset of glioblastoma (GBM), usually associated with the mesenchymal molecular subtype. NF1 loss was associated with worse overall and disease-specific survival in the lower-grade glioma, but not the GBM group in the Cancer Genome Atlas cohort. IDH1 or 2 mutations co-existed in lower-grade gliomas with NF1 loss (36%) but not in GBM