Table 1.

In the 2016 WHO classification of “diffuse gliomas” (grades II-IV), are classified in two groups based on the Isocitrate Dehydrogenase genes (IDH1 and 2), wildtype versus mutant status.

Cell Type	Classification	Histological Grading	Molecular Classification
‘Diffuse’ astrocytomas	Diffuse astrocytoma (A)	II	IDH wildtype (30%) IDH mutant (70%)
	Anaplastic astrocytoma (AA)	III
	Glioblastoma (GB)	IV	IDH wildtype (90%) IDH mutant (10%)
Oligodendrogliomas	Oligodendroglioma (O)	II	IDH mutant (100%) 1p19q codeleted (100%)
	Anaplastic oligodendroglioma (AO)	III