Cross-Platform Calibration of Epigenetic Age Between the EPICv2 and MSA Arrays

Abstract

Epigenetic clocks are regression models that predict biological age based on the DNA methylation patterns. They are developed using DNA methylation array data; however, systematic differences in the predicted values between the Infinium Methylation Screening Array (MSA) and Infinium MethylationEPIC v2.0 BeadChip (EPICv2) platforms have not been evaluated. We quantified the systematic differences between the MSA and EPICv2 arrays for six major epigenetic clocks (Horvath, Hannum, PhenoAge, GrimAge, GrimAge v2, and DunedinPACE) using 166 human blood samples measured on both platforms. For the five clocks expressed in years, the mean differences (MSA - EPICv2) ranged from -7.67 years for the Horvath clock to -0.634 years for GrimAge v2, despite strong correlations between platforms (r = 0.946-0.991). For DunedinPACE, which predicts the pace of aging, the mean difference was -0.117, with a correlation coefficient of 0.855 between the platforms. Based on these training data, we developed three linear regression models to map the MSA-based epigenetic ages and pace of aging to the EPICv2-based values, which were used as a reference: Model 1 (offset location calibration), Model 2 (slope and location calibration), and Model 3 (slope and location calibration with covariates). Validation using 48 independent samples measured at separate institutions showed that the calibration models reduced cross-platform differences for Horvath, Hannum, PhenoAge, GrimAge, and DunedinPACE. Although Model 3 yielded mean differences closest to zero for the Horvath clock (-0.227 years) and PhenoAge (-0.510 years), Model 1, the simplest specification, also reduced the mean cross-platform differences to -1.03 years for the Horvath clock and -1.37 years for PhenoAge. For DunedinPACE, Model 1 reduced the mean difference from -0.092 to 0.025 and the RMSE from 0.103 to 0.052. These methods are expected to enable reliable epigenetic age comparisons across platforms and facilitate large-scale epigenetic studies.