The mean maximum tumor diameter was 4.19, 4.96, and 4.17 cm for diffuse astrocytoma, MYB- or MYBL1-altered, diffuse midline glioma, H3 K27-altered, and diffuse pediatric-type high-grade glioma, H3-wildtype and IDH-wildtype, respectively. This evidence concerns the gene IDH1 and diffuse midline glioma.