IDH1 and oligodendroglioma: Because 1p/19q-codeletions are directly computable from SCNA data, we proposed a two-stage classification system for the prediction of adult diffuse glioma molecular subtype in which 1p/19q-codeleted oligodendrogliomas are identified in the first phase and the remaining diffuse astrocytic tumors are passed through a binary IDH mutation classifier in the second phase (Fig. 1D).