IDH1 and astrocytoma (excluding glioblastoma): To independently validate histological diagnoses and NGS findings, as well as to explore further the relationship of EGFR-amplified IDH-mutant astrocytomas to other CNS tumors, we performed clinically validated NYU whole-genome DNA methylation profiling using Illumina EPIC array and analyzed using the Heidelberg brain tumor classifier.9 Notably, all four cases were classified as “IDH-mutant High-Grade Astrocytoma” with high confidence scores (0.99 0.997, 0.98, and 0.99; cases 1-4, respectively).