IDH1 and central nervous system cancer: For example, IDH-mutant gliomas, encompassing both astrocytoma and oligodendroglioma, predominantly occur in individuals under the age of 55 and are more frequently localized in the frontal lobe and insula.14The “T2-FLAIR mismatch” sign stands as the most specific imaging marker for distinguishing IDH-mutant astrocytoma from IDH-mutant, 1p/19q co-deleted oligodendroglioma and IDH-wildtype glioblastomas.