KIAA1549 and pilocytic astrocytoma: Cerebellar pilocytic astrocytomas often exhibit MAPK/ERK hyperactivation as a consequence of a KIAA1549–BRAF fusion.3,4 LGGs occurring elsewhere in the brain have a higher percentage of tumors with a point mutation in BRAF at codon 600 (BRAFV600E and variants such as BRAFV600D).