Table 1.

Classification of gliomas according to the new 2021 WHO Classification [10]. The abbreviations are given in the Abbreviations section.

	WHO Grade	Most Common Molecular Features
Circumstribed gliomas
Pilocytic astrocytoma	1	KIAA1549-BRAF [11]
High-grade astrocytoma with piloid features	new subtype	specific DNA-methylation profile [12]
Pleomorphic xanthoastrocytoma	2, 3	BRAF [13]
Subependymal giant cell astrocytoma	1	TSC1, TSC2 [14]
Chordoid glioma	2	PRKCA [15]
Astroblastoma, MN1-altered	new subtype	MN1 [16]
Pediatric diffuse low grade gliomas
Diffuse astrocytoma, MYB- or MYBL1-altered	1	MYB, MYBL1 [17]
Angiocentric glioma	1	MYB [10]
Polymorphous low-grade neuroepithelial tumor of the young	1	PLNTYs, BRAF, FGFR [18]
Diffuse low-grade glioma, MAPK pathway-altered	new subtype	FGFR1, BRAF [19]
Pediatric-type diffuse high-grade gliomas
Diffuse midline glioma, H3 K27-altered	4	H3 K27 [20]
Diffuse hemispheric glioma, H3 G34-mutant	4	H3F3A (G34R/V) [21], GFAP [22], p53 [23]
Diffuse pediatric-type high-grade glioma, H3- and IDH-wt	4	IDH-wt, H3-wt, MYCN, PDGFRA [24]
Infant-type hemispheric glioma	new subtype	NTRK, ALK, ROS1, MET [25]
Adult-type diffuse gliomas
Astrocytoma, IDH-mutant	2, 3, 4	IDH1, IDH2 [26], ATRX [27]
Oligodendroglioma, IDH-mutant, and 1p/19q-codeleted	2, 3	IDH [28], 1p19q-codeletion, ATRX, p53 [29]
Glioblastoma, IDH-wt	4	no IDH mutation (IDH-wt), ATRX, TERT [30]