Genomic Alteration Patterns Across Histological Grades in <i>BRAF</i> p.V600E‐Mutant Gliomas and Glioneuronal Tumors: An Analysis of 15 Cases

BRAF p.V600E-mutant gliomas and glioneuronal tumors comprise a wide clinicopathological spectrum, yet the relationship between genomic alteration burden and histological grade remains incompletely defined. We analyzed 15 BRAF p.V600E-mutant gliomas and glioneuronal tumors across histological grades using the PleSSision Rapid sequencing platform. Single-nucleotide variants (SNVs) and copy-number alterations were assessed in parallel to characterize genomic alteration profiles. Low-grade tumors generally exhibited limited genomic alterations; however, a subset of low-grade tumors showed increased numbers of SNVs. High-grade tumors demonstrated more extensive genomic alterations, characterized predominantly by copy-number gains. A trend toward increased copy-number gains with higher WHO grade was observed. Homozygous deletion of CDKN2A was observed in pleomorphic xanthoastrocytoma, including both CNS WHO grade 2 and grade 3 tumors, and epithelioid glioblastoma. These findings indicate substantial genomic heterogeneity among BRAF p.V600E-mutant gliomas and glioneuronal tumors. While low-grade tumors are generally genomically quiet, a subset shows increased alterations, and high-grade tumors tend to acquire copy-number changes, highlighting the limitations of genomic event counts alone as a surrogate for malignant potential.