IDH1 and astrocytoma (excluding glioblastoma): IDH mutations are class-defining alterations in adult diffuse gliomas (Yan et al., 2009; Waitkus et al., 2016; Gupta et al., 2013) which are classified into 3 types: Astrocytoma, IDH mutant; Oligodendroglioma, IDH mutant and 1p/19 codeleted and Glioblastoma, IDH wildtype.