Genetic mechanisms such as activation of MAPK, BRAF gene deregulation and neurofibromatosis type 1 (NF1) syndrome have been associated with PA development.
KIAA1549-BRAF is the most frequently identified genetic mutation in sporadic pilocytic astrocytoma (PA), creating a fusion BRAF (f-BRAF) protein with increased BRAF activity.
Our results further emphasize the importance of BRAF alterations in PA and the need to characterize them in a given tumor as this can affect therapeutic strategies and their potential use as tumor marker in molecular diagnostics.
More recently, cases of PA with gangliocytic differentiation (PA-GD) have been described, and these cases are thus far restricted to those with the KIAA1549-BRAF fusion.
KIAA1549-BRAF is the most frequently identified genetic mutation in sporadic pilocytic astrocytoma (PA), creating a fusion BRAF (f-BRAF) protein with increased BRAF activity.
The review of imaging features indicated that cyst formation is associated with the existence of KIAA1549-BRAF fusion in PA and GG and the lack of BRAF mutation in GG.
More recently, cases of PA with gangliocytic differentiation (PA-GD) have been described, and these cases are thus far restricted to those with the KIAA1549-BRAF fusion.
The review of imaging features indicated that cyst formation is associated with the existence of KIAA1549-BRAF fusion in PA and GG and the lack of BRAF mutation in GG.
BRAF-V600E mutations are most commonly found in pleomorphic xanthoastrocytoma, ganglioglioma, epithelioid glioblastoma, and gliomas diagnosed at a younger age; BRAF-KIAA1549 fusion is the most common BRAF alteration in pilocytic astrocytoma.
BRAF fusion involving the KIAA1549 gene is a hallmark of pilocytic astrocytoma, but it has also been recorded in rare cases of gangliogliomas, 1p/19q co-deleted oligodendroglial tumors, and it is also a common feature of disseminated oligodendroglial-like leptomeningeal neoplasm.
BRAF-V600E mutations are most commonly found in pleomorphic xanthoastrocytoma, ganglioglioma, epithelioid glioblastoma, and gliomas diagnosed at a younger age; BRAF-KIAA1549 fusion is the most common BRAF alteration in pilocytic astrocytoma.
BRAF fusion involving the KIAA1549 gene is a hallmark of pilocytic astrocytoma, but it has also been recorded in rare cases of gangliogliomas, 1p/19q co-deleted oligodendroglial tumors, and it is also a common feature of disseminated oligodendroglial-like leptomeningeal neoplasm.
A recurrent feature of PA is deregulation of the mitogen activated protein kinase (MAPK) pathway most often through KIAA1549-BRAF fusion, but also by other BRAF- or RAF1-gene fusions and point mutations (e.g.BRAFV600E).
KIAA1549-BRAF fusion is the most common genetic event in pilocytic astrocytoma (PA), and leads to activation of the mitogen activated protein kinase (MAPK) signaling pathway.
Using a combined analysis of RNA sequencing and copy number variation data we identified a new BRAF fusion involving the 5' gene fusion partner GTF2I (7q11.23), not previously described in PA.