Table 2.

Essential and desirable criteria for the diagnosis of IDH-mutant gliomas

Tumor type	Essential criteria	Desirable criteria	Additional altered genes
Astrocytoma, IDH-mutant	Diffusely infiltrating glioma	Astrocytic differentiation by morphology	CDKN2A, CDKN2B, CDK4, CCND2, PDGFRA, MET, MYC, MYCN, RB1, PIK3R1, PIC3CA, others
	IDH1/2 hotspot mutation	TP53 mutation or strong nuclear expression of p53 in > 10% of tumor cells
	ATRX loss or ATRX mutation OR exclusion of combined whole-arm deletions of 1p and 19q	Methylation profile of astrocytoma, IDH-mutant
Oligodendroglioma, IDH-mutant and 1p/19q-codeleted	Diffusely infiltrating glioma	Retained nuclear expression of ATRX	CDKN2A, CDKN2B, CIC, FUBP1, NOTCH1
	IDH1/2 hotspot mutation	TERT promoter mutation
	Combined whole-arm deletions of 1p and 19q	DNA methylome profile of oligodendroglioma, IDH-mutant and 1p/19q-codeleted