Based on these results, the authors classified the tumors into three groups 1) “molecular astrocytomas”: tumors with IDH mutation and without 1p/19q co-deletion, including mixed AOA with ATRX loss and AA with and without ATRX loss; 2) “molecular oligodendrogliomas”: tumors with IDH mutation and ATRX expression including AOA harboring 1p/19q co-deletion and AO with and without 1p/19q co-deletion; 3) “molecular glioblastomas”: tumors with IDH wild-type. This evidence concerns the gene IDH1 and oligodendroglioma.