The 2021 WHO CNS5 diagnoses across 4023 eligible patients included glioblastoma, IDH-wildtype [n = 1713, 1015 male, 657 female, median age 60.52 years, interquartile range (IQR) 16.55 (51.99–68.46)]; astrocytoma, IDH-mutant [n = 1186, 635 male, 495 female, median age 38.18 years, IQR 15.31 (31.20–46.51)]; oligodendroglioma, IDH-mutant and 1p/19q codeleted [n = 836, 424 male, 364 female, median age 44.36 years, IQR 19.29 (35.26–54.55)]; and ‘other glioma’ tumour diagnoses [n = 288, 151 male, 127 female, median age 25.32 years, IQR 29.82 (13.24–43.06)] (Table 1 and Supplementary Fig. 1). The gene discussed is IDH2; the disease is glioma.