Incidence of kiaa1549-braf fusion gene in Egyptian pediatric low grade glioma

BACKGROUND Low grade gliomas are the most common brain tumor in children. Tandem duplication involving the KIAA1549 and the BRAF kinase genes results in a gene fusion that has been recently characterized in a subset of low grade glioma While there is no clear evidence that the KIAA1549-BRAF gene fusion has an effect on prognosis, it is an attractive target for therapy development and as a diagnostic tool. METHODS In the current study we examine the prevalence of KIAA1549-BRAF gene fusion in pediatric patients diagnosed with low grade glioma in the Egyptian population and its relationship to clinical and histological subtypes. Sixty patients between the ages of 1 to 18 years were analyzed for the presence of KIAA1549-BRAF fusion gene products using reverse transcription-PCR and sequencing. The clinicopathologic tumor characteristics were then analyzed in relation to the different fusion genes. RESULTS KIAA1549-BRAF fusion genes were detected in 56.6% of patients. They were primarily associated with pilocytic astrocytoma (74.2%) and pilomyxoid astrocytoma (60%). Translocation 15-9 was the most common, representing (55.8%) of all positive samples followed by 16-9 (26.4%) and 16-11 (8.8%). Pilocytic astrocytomas presented primarily with 15-9 (32.2%), 16-9 (25.8%) and 16-11 (6.4%) while pilomyxoid astrocytomas presented with 15-9 (46.6%), 16-9 (6.6%) and 16-11 (6.6%) translocations. CONCLUSION Gene fusion is found to be significantly increased in cerebellar pilocytic astrocytoma tumors. Furthermore, 15-9 was found to have a higher incidence among our cohort compared to previous studies. While most of the gene fusion positive pilomyxoid astrocytomas were 15-9, we find the association none significant.