Fig. 4

DNA methylation entropy (HME) of GBM in function of genome location. The entropy metrics based on DNA methylation (HME) was determined by genome location, constituted of the Island regions (CpG islands, shores, shelves or open sea) and promoter location (promoter or not in promoter). The Eigenvalues of the PCA of the dataset containing the HME metrics suggest that the first two dimensions explain most of the variability, a. The entropy (HME metrics) stratified by genome location was projected on the first vectorial plane (axes 1 & 2) of the PCA b. The colors of the arrows and labels indicate the genome location in (blue) or outside (red) of a promoter. c The contribution of DNAm age acceleration (Accel), age (Age) and GBM classification (Class) to HME was determined by variation partitioning and visualized in a Venn diagram containing the variation fractions. d The GBM samples are represented on the first vectorial plane of the PCA for global HME, annotated for GBM classification (MES, red; RTK I, green; RTK II, blue). Boxplot representation of global entropy e and entropy of CpGs located in promoter islands f is visualized by GBM classification. The association of classification with entropy by genome location was examined by Wald test (Additional file 1: Table S4)