DLL1 and central nervous system cancer: In addition to the genes whose expression was previously shown to be associated with the PM glioma type [17, 18], additional genes that regulate the specification and maintenance of pre-OPC and OPC (ASCL1, CSPG4/NG2, DLL1, DLL3, HES6, PTPRZ1) and inhibitors of OPC differentiation or OL lineage terminal differentiation (ID4, SOX6 and GPR56) [42, 58, 63] were consistently enriched in PM gliomas as was the NFOL marker TCF7L2/TCF4 [64, 65] (Fig. 2B and C and Additional file 1: Fig. S7B and C).