TP53 and astrocytoma (excluding glioblastoma): Although 30% to 70% of oligoastrocytomas have LOH 1p and LOH 19q,8, 9, 10, 11, 12, 15 indicating a genetic resemblance to oligodendrogliomas, only 30% of oligoastrocytomas have mutations in the TP53 gene or LOH 17p,10, 16 indicating a link to astrocytomas.