Figure 1. Correlation of chronological age and biological age. Chronological age was positively correlated with each of the three epigenetically-predicted ages. Intrinsic age and chronological age were highly correlated (r = 0.91, p < 2.2e-16, (A), as were extrinsic age and chronological age (r = 0.91, p < 2.2e-16, (B), and phenotypic age and chronological age (r = 0.91, p < 2.2e-16, (C). The red line indicates the regression of the epigenetically-predicted age on the chronological age. The blue line is a 1:1 line for comparison.