IDH1 and glioma: Oligodendroglioma (ODG) accounts for 5–9% of all gliomas [1] (CBTRUS statistical report: NPCR and SEER; 2006–2010) and is classified by World Health Organization (WHO, 2016) into IDH1 mutant and 1p/19q co-deleted grade II and IDH1 mutant and 1p/19q co-deleted anaplastic grade III ODGs [2].