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). This evidence concerns the gene TP53 and anaplastic oligoastrocytoma.