IDH1 and glioma: Neurotransmission-based unsupervised clustering enabled the proper classification of the majority of infiltrating gliomas into current WHO tumor categories (IDH-wt gliomas, IDH-mutated, 1p/19q oligodendrogliomas and IDH-mutated astrocytomas), suggesting that neurotransmission-related pathways are differentially regulated in tumor cells and/or their microenvironment according to tumor subtype, and also reaffirming the importance of IDH1/2 mutations and of 1p/19q-codeletion for glioma stratification.