GB is recognised as an isocitrate dehydrogenase (IDH)-wildtype diffuse glioma and the revised 2021 WHO classification of CNS tumours no longer includes the term ‘IDH-mutant glioblastoma.’ Instead, it is now categorised as Astrocytoma, IDH-mutant, encompassing CNS grade 2–4 tumours [2]. The gene discussed is IDH2; the disease is glioblastoma.