While mutational signature SBS14 was previously detected in a hypermutated oligodendroglioma of a patient with de novo POLE exonuclease variant p.(L424V) [9], mutational signatures SBS10 or SBS20 were found in six of 14 (43%) gliomas, two of which were hypermutated, from patients with rare POLE/POLD1 variants here, providing evidence for defective polymerase proofreading in these tumors. The gene discussed is POLD1; the disease is oligodendroglioma.