Pediatric-type diffuse high-grade gliomas comprise four tumor types that include diffuse midline glioma, H3 K27-altered;diffuse hemispheric glioma, H3 G34-mutant; diffuse pediatric-type high-grade glioma, H3-wildtype and IDH-wildtype, andinfant-type hemispheric glioma. The gene discussed is IDH1; the disease is neoplasm.