Fig. 1

Characteristics of epigenetic clocks. A Prediction of age by the four epigenetic clocks. Prediction accuracy was analyzed using Pearson correlation (r) between chronological and predicted age, as well as mean absolute error (MAE) of the predicted ages. B Concordance of the age prediction errors of the epigenetic clocks, analyzed using Pearson correlation (r) between the prediction errors of each clock pair. C Overlap of the CpGs comprising the epigenetic clocks. The cells on the diagonal represent total clock size, while the other cells represent the number of CpGs shared between each clock pair. The color of each cell represents the percentage of the smaller CpG set that overlaps with the larger CpG set (0% = white, 100% = red). D Percentage of each clock’s CpGs which have a proxy (defined by absolute Pearson correlation above 0.5) within the same clock or in the 3 other clocks. Percentages with a proxy correlation of at least 0.5, 0.7, and 0.9 are plotted in stacked bar charts. Correlations within a clock are marked with an asterisk (*). E Enrichment of clock CpGs in CpG-island-centric features (top section), histone modifications (middle section), and chromatin states according to ChromHmm (bottom section). Abbreviations: OR: odds ratio; CGI: CpG island; TssA: Active transcription start site; TssAFlnk: flanking active transcription start site; TxFlnk: transcription at gene 5' and 3'; Tx: strong transcription; TxWk: weak transcription; EnhG: genic enhancers; Enh: enhancers; ZNF/Rpts: ZNF genes plus repeats; Het: heterochromatin; TssBiv: bivalent/poised transcription start site; BivFlnk: flanking bivalent transcription start site/enhancer; EnhBiv: bivalent enhancer; ReprPC: repressed polycomb; ReprPCWk: weak repressed polycomb; Quies: quiescent/low