title: Genetic profile of astrocytic and oligodendroglial gliomas.
abstract: Low-grade diffuse gliomas WHO grade II (diffuse astrocytoma, oligoastrocytoma, oligodendroglioma) are characterized by frequent IDH1/2 mutations (>80%) that occur at a very early stage. In addition, the majority of diffuse astrocytomas (about 60%) carry TP53 mutations, which constitute a prognostic marker for shorter survival. Oligodendrogliomas show frequent loss at 1p/19q (about 70% of cases), which is associated with longer survival. With respect to clinical outcome, molecular classification on the basis of IDH1/2 mutations, TP53 mutations, and 1p/19q loss showed a predictive power similar to histological classification. IDH1/2 mutations are frequent (>80%) in secondary glioblastomas that have progressed from low-grade or anaplastic astrocytomas. Primary (de novo) glioblastomas with IDH1/2 mutations are very rare (<5%); they show an age distribution and genetic profile similar to secondary glioblastomas and are probably misclassified. Using the presence of IDH1/2 mutations as a diagnostic criterion, secondary glioblastomas account for approximately 10% of all glioblastomas. IDH1/2 mutations are the most significant predictor of favorable outcome of glioblastoma patients. The high frequency of IDH1/2 mutations in oligodendrogliomas, astrocytomas, and secondary glioblastomas derived thereof suggests these tumors share a common progenitor cell population. The absence of this molecular marker in primary glioblastomas suggests a different cell of origin; both glioblastoma subtypes acquire a similar histological phenotype as a result of common genetic alterations, including the loss of tumor suppressor genes on chromosome 10q.
authors: Molecular Pathology Section, International Agency for Research on Cancer, 150 Cours Albert Thomas, 69372 Lyon, France. ohgaki@iarc.fr
authors: Hiroko
authors: H
authors: Ohgaki
authors: Paul
authors: P
authors: Kleihues
mesh_terms: D000328:Adult; D000368:Aged; D001253:Astrocytes / Q000473:pathology; D014408:Biomarkers, Tumor / Q000235:genetics*; D001932:Brain Neoplasms / Q000235:genetics*; D002872:Chromosome Deletion; D002878:Chromosomes, Human, Pair 1; D002888:Chromosomes, Human, Pair 19; D005909:Glioblastoma / Q000175:diagnosis / Q000235:genetics; D006801:Humans; D007521:Isocitrate Dehydrogenase; D008875:Middle Aged; D009154:Mutation; D009836:Oligodendroglia / Q000473:pathology; D009837:Oligodendroglioma / Q000175:diagnosis / Q000235:genetics; D011379:Prognosis; D016159:Tumor Suppressor Protein p53
chemical_list: D014408:Biomarkers, Tumor; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; C538784:IDH2 protein, human; D007521:Isocitrate Dehydrogenase; C543588:IDH1 protein, human