Consequently, they were able to show that classifying tumors based on IDH and 1p19q status mapped universally to a specific cluster, whereas histologic designation (i.e., oligodendroglioma, astrocytoma, and oligoastrocytoma) matched one-to-one with a cluster only 63% of the time. This evidence concerns the gene IDH2 and astrocytoma (excluding glioblastoma).