The newly established molecular subgroup comprises four distinct entities: 1) Diffuse astrocytoma, MYB or MYBL1-altered; 2) Angiocentric glioma; 3) Polymorphous low-grade neuroepithelial tumor of the young; and 4) Diffuse low-grade glioma, MAPK pathway-altered. The gene discussed is MYB; the disease is astrocytoma (excluding glioblastoma).