IDH1 and oligoastrocytoma: Patient stratification for the histological type revealed that EMP3 promoter hypermethylation was significantly associated with IDH1/IDH2 mutations in astrocytic tumors (P = 0.0088), GBMs included (P = 0.0012), in oligodendroglial tumors (P = 0.0006), and in oligoastrocytomas (P = 0.0095).