Characterization of KIAA1549:BRAF fusion in young pilocytic astrocytoma patients through fluorescence in situ hybridization.

Abstract

10067 Background: Pilocytic astrocytoma (PA) often arises in young patients and may be related to type 1 neurofibromatosis (NF1). Although the 5-year survival is high, up to 10% of cases progress poorly. Alterations of BRAF mainly through gene fusions are key genetic events in this tumor type, and are reported to influence patient outcome. Our aim was to assess BRAF molecular changes in PAs for both p.V600E mutation and KIAA1549:BRAF (K:B) fusion and correlate with clinicopathological features in retrospective studies. Methods: Sanger sequencing was used to evaluate BRAF V600E mutation. K:B fusion was evaluated by a customized dual-target, dual-color fluorescence in situ hybridization (FISH) probe set in samples in tissue microarray format. The designed K:BFISH probe was validated in Agilent 8x60K aCGH and RT-PCR assays in 5 cases. Results: A total of 75 samples were evaluated from 69 patients (1.2 M/F), mean age of 11.6 years and long-term follow-up (7-196 months). Cerebellum was the main location (53.6%...