IDH1 and neoplasm: The protocol that we suggest differs from that of Filipski et al. in that the latter classifies all tumours with retained H3K27me3 as astrocytic, with no additional tests [14], while cases with H3K27me3 loss are tested for ATRX and IDH mutations, and those IDH-mutant with retained or non-conclusive ATRX are considered oligodendroglial [14].