POLR2D and cancer: Most of the genes corresponding to the 31 CpGs have been reported to be involved in the tumorigenesis or prognosis of cancer, including ATOH1, ATPIG1, ELL3, RBM15B, GATA4, TXN, DLX5, THSD4, Polr2d, LGALS3BP, HIST1H3D, FLRT1, IFI35 and OSBPL5. Among these genes, hypermethylation of THSD4 has been reported to be associated with the prediction of prognosis in GBM (Ma et al., 2015), and Polr2d expression is associated with the therapy response of GBM (Serao et al., 2011).