IDH1 and oligodendroglioma: When excluding 1p19q codeleted tumors (considered as the hallmark of oligodendrogliomas), TP53 mutation was even more strongly correlated with IDH mutation: 57/98 (58.2%) of IDH mutated tumors was also mutated on TP53, versus 46/175 (26.2%, P < 0.0001) in nonmutated gliomas.