Figure 4. Correlation of DNA methylation levels and comparison to 450K arrays. The heatmaps show matrices of Pearson’s correlation coefficients across (A) BL samples (n = 497 CpG sites) and (B) SCL samples (n = 1581 CpG sites), assessed using the BM panel. The DNA methylation levels of unamplified samples with a starting DNA amount between 100 ng and 1500 ng were strongly correlated (median R = 0.98). Further, we correlated a subset of these CpG sites, i.e., n = 81 and n = 204 CpGs across BL and SCL samples, that are represented on the 450K array. We found a strong correlation (R ≥ 0.91) for unamplified samples and a moderate correlation (R ≥ 0.79) for WGA samples. Panels (C) and (D) show the distribution of DNA methylation scores at the assessed CpG sites.