With recent molecular advancements, the 2021 World Health Organization Classification of Central Nervous System Tumours describes a classification system that centres on the integration of molecular markers and, in some cases, DNA methylome profiling for the diagnosis and categorization of gliomas.1 To date, molecular testing has revealed the clinical and prognostic significance of isocitrate dehydrogenase (IDH) mutation status. The gene discussed is IDH1; the disease is glioma.