Patients with suspected dLGG were classified into three categories based on molecular subtypes: patients with IDH mutation and 1p/19q codeletion (i.e., oligodendroglioma), patients with IDH mutation and non-1p/19q codeletion (i.e., IDHmut astrocytoma), and patients with IDHwt (i.e., IDHwt astrocytoma). This evidence concerns the gene IDH1 and oligodendroglioma.