According to the new WHO CNS5 classification, 4 tumor types have been identified: (i) diffuse astrocytoma, MYB- or MYBL1-altered; (ii) angiocentric glioma; (iii) polymorphic neuroepithelial tumor of the young; (iv) diffuse low-grade, mitogen-activated protein kinase (MAPK) pathway-altered glioma. The gene discussed is MYBL1; the disease is glioma.