They included 20 cases of oligodendroglioma (IDH1 mutation and 1p19q codeletion), 22 cases of IDH-mutant astrocytoma (IDH1 mutation and 1p19q non-codeletion), and 22 cases of IDH-wild-type astrocytoma (IDH1 wild type and 1p19q non-codeletion). Here, IDH1 is linked to oligodendroglioma.