ATRX and astrocytoma (excluding glioblastoma): In order to distinguish several cell populations in IDH-DGIIG tumors, we examined three diffuse grade II astrocytoma tumors with IDH1 R132H and ATRX mutations and three diffuse grade II oligodendroglioma tumors with an IDH1 R132H mutation and a 1p19q codeletion (Table S1).