Selecting for common glioma mutations and copy number alterations clearly shows three distinct subtypes of adult type diffuse gliomas as defined by the fifth edition of the WHO Classification of Tumors of the Central Nervous System (WHO CNS5)13-IDHmutant-1p19q co-deleted oligodendrogliomas, the IDH mutant astrocytomas with TP53 and ATRX mutations, and the IDH-wildtype (IDH-wt) glioblastomas with gain of chromosome 7 and loss of chromosome 10. The gene discussed is IDH1; the disease is oligodendroglioma.