We show that PI3-kinase mutations are associated with poor prognosis in molecular astrocytomas (i.e. diffuse gliomas that are IDH-mutated and 1p19q intact (or ATRX/TP53 mutated)) and that no other marker investigated in this study appears to further refine this molecular/prognostic classification of diffuse gliomas. The gene discussed is IDH2; the disease is astrocytoma (excluding glioblastoma).