Topographic correlates of driver mutations and endogenous gene expression in pediatric diffuse midline gliomas and hemispheric high-grade gliomas

Abstract

We evaluate the topographic distribution of diffuse midline gliomas and hemispheric high-grade gliomas in children with respect to their normal gene expression patterns and pathologic driver mutation patterns. We identified 19 pediatric patients with diffuse midline or high-grade glioma with preoperative MRI from tumor board review. 7 of these had 500 gene panel mutation testing, 11 patients had 50 gene panel mutation testing and one 343 gene panel testing from a separate institution were included as validation set. Tumor imaging features and gene expression patterns were analyzed using Allen Brain Atlas. Twelve patients had diffuse midline gliomas and seven had hemispheric high-grade gliomas. Three diffuse midline gliomas had the K27M mutation in the tail of histone H3 protein. All patients undergoing 500 gene panel testing had additional mutations, the most common being in ACVR1, PPM1D, and p53. Hemispheric high-grade gliomas had either TP53 or IDH1 mutation and diffuse midline gliomas had H3 K27M-mutation. Gene expression analysis in normal brains demonstrated that genes mutated in diffuse midline gliomas had higher expression along midline structures as compared to the cerebral hemispheres. Our study suggests that topographic location of pediatric diffuse midline gliomas and hemispheric high-grade gliomas correlates with driver mutations of tumor to the endogenous gene expression in that location. This correlation suggests that cellular state that is required for increased gene expression predisposes that location to mutations and defines the driver mutations within tumors that arise from that region.

Molecular Characterization and Treatment Approaches for Pediatric H3 K27-Altered Diffuse Midline Glioma: Integrated Systematic Review of Individual Clinical Trial Participant Data

“…The prevalence of TP53 was seen in thalamic tumors at a higher percentage compared to those in the pons in our study. Within the literature, the incidence of TP53 has not been well established with the anatomical location of the tumor but has been shown to be prevalent within all midline locations [ 1 , 23 ]. The ACVR mutation showed a protective effect on OS in our analysis.…”

Midline Gliomas: A Retrospective Study from a Cancer Center in the Middle East

“…The consortium also acknowledges the presence of H3 K27M mutations within a number of other CNS tumors. Other gene mutations including p53, ACVR1, ATRX, and PI3K have been associated with DMG [ 4 , 5 , 6 , 7 ]. Subsequently, based on the latest WHO CNS tumors classification in 2021, these tumors are now described as H3 K27-altered gliomas, CNS WHO grade 4 [ 8 ].…”