IDH1 and oligodendroglioma: One of the most prominent examples is the inclusion of isocitrate dehydrogenase (IDH) 1 and 2 status, and loss of chromosomes 1p and 19q as integrated parts of the classification of glioma: Since 2016 the diagnosis of astrocytomas requires the analysis of IDH mutation status, and the diagnosis of oligodendrogliomas requires the assessment of both IDH mutations, as well as combined 1p/19q losses.