TP53 and oligodendroglial tumor: p53 immunohistochemistry positivity was detectable in only 30% of 1p/19q non-codeleted oligodendroglial tumors among 90 cases examined, including seven anaplastic oligodendrogliomas, 13 oligoastrocytomas and seven anaplastic oligoastrocytomas (Supplementary Figure S1c).