(Figure 2C, p=3.57×10−24) and non-neuronal cells (Figure 2D, p=8.09×10−86). The composition values of the fifth cell type in the dataset (ES-derived dopamine neurons) did not differ between pre- and post-natal samples (p=0.99). These composition profiles explained much of the variability in DNAm levels at individual CpGs, particularly at those differentially methylated from prenatal to postnatal life (Figure 2E). Also, by utilizing the DNAm-derived composition profiles in the expression data, we found significant, but lesser, association with gene expression levels (Supplementary Figure 5). We hypothesize these weakened associations with composition in gene expression data may result from additional layers of unexplored epigenetic regulation, as well as the fact that DNA and RNA from some of these samples were obtained from different tissue dissections.
