Table 1.

Table Frequencies of KIAA1549:BRAF (B–K) Fusion and BRAF V600E Mutations in Pediatric Gliomas

BRAF alteration	BRAF location
	Cerebellum	Supratentorial	Non-cerebellar infratentorial	Optic nerve
B–K fusion	74.2 %	33.2 %	50.6 %	54.2 %
V600E	2.9 %	17.9 %	1.6 %	15.0 %

BRAF alteration	BRAF histology
	PA	PMA	PXA	GG	DA	HGG
B–K fusion	66.6 %	50.0 %	0.0 %	21.2 %	11.9 %	0.0 %
V600E	5.7 %	7.7 %	73.8 %	19.2 %	9.7 %	13.1 %

At least half of all posterior fossa/infratentorial and optic nerve low-grade gliomas have a B–K fusion, whereas only one third of all supratentorial non-optic nerve tumors have this alteration. In contrast, BRAF^V600E mutation is most common in the supratentorium, although still half as frequent as the B–K fusion in this region. BRAF fusions are more associated with PAs and PMAs than any other histotype. Although some studies have identified B–K fusions in non-PA tumors, current thinking is that such tumors may be better classified as a PA or PMA, even if they resemble GGs or DAs. V600E mutations show less restriction in histotype, but are most common in PXAs and GGs. Although not listed in the Table, FAM131B:BRAF, SRGAP3:RAF1, and BRAF^ins598T mutations occur in 1%–2% of all PAs. These data were extracted and compiled from an aggregate of over 700 pediatric gliomas published by multiple groups (5–11, 15, 17, 20, 22, 33, 34, 45). PA = pilocytic astrocytoma; PMA = pilomyxoid astrocytoma; PXA = pleomorphic xanthoastrocytoma; GG = ganglioglioma; DA = grade II diffuse astrocytoma; HGG = high-grade glioma.