Given our findings, we advocate for prospective molecular testing on gliomas arising in the setting of NF1 to stratify them into prognostically and therapeutically relevant low-grade versus high-grade molecular groups, and DNA methylation profiling to accurately classify high-grade tumors into HGAP, IDH-wildtype glioblastoma, or other subtypes. The gene discussed is IDH1; the disease is glioblastoma.