Neuro-oNcology

We screened exon 4 of the gene isocitrate dehydroge-nase 1 (NADP+), soluble (IDH1) for mutations in 596 primary intracranial tumors of all major types. Codon 132 mutation was seen in 54 % of astrocytomas and 65 % of oligodendroglial tumors but in only 6 % of glioblastomas (3 % of primary and 50 % of secondary glioblastomas). There were no mutations in any other type of tumor studied. While mutations in the tumor protein p53 gene (TP53) and total 1p/19q deletions were mutually exclusive, IDH1 mutations were strongly cor-related with these genetic abnormalities. All four types of mutant IDH1 proteins showed decreased enzymatic activity. The data indicate that IDH1 mutation com-bined with either TP53 mutation or total 1p/19q loss is a frequent and early change in the majority of oligo-dendroglial tumors, diffuse astrocytomas, anaplastic astrocytomas, and secondary glioblastomas but not in primary glioblastomas. Neuro-Oncology 11, 341–347