For example, workup may be pursued to assess for the possibility of other IDH-wildtype tumours, such as diffuse hemispheric gliomas characterized by H3 G34-mutations, diffuse midline gliomas defined by H3 K27 alterations, or MAPK pathway altered gliomas, such as pleomorphic xanthroastrocytoma (Figure 2). The gene discussed is IDH1; the disease is central nervous system cancer.