Prime 8

Genomic DNA was extracted from buffy coat fractions of anti‐coagulated blood samples using Chemagic DNA buffy coat kit (PerkinElmer, Germany) with Chemagic Magnetic Separation Module 1 and Chemagic Prime 8 Automated Workstation, and was subsequently bisulfite converted using the EZ‐96DNA Methylation‐Lightning™ MagPrep from Zymo according to the manufacturer's instructions. DNA methylation levels were measured on Illumina iScan using Illumina's Human MethylationEPIC BeadChip. The methylation level for each probe was derived as a beta value representing the fractional level of DNA methylation at that probe. Sample‐level and probe‐level quality control were performed using the “minfi” package (Fortin et al., 2017 (link)) in R. Probes with a missing rate > 1% (at a detection p‐value > 0.01) were excluded. Samples with sex mismatch or a missing rate at >1% across all probes were also excluded following previously published recommendation guidelines for analyzing methylation data (Wu & Kuan, 2018 (link)).

Genomic DNA was extracted from buffy coat fractions of anti-coagulated blood samples using Chemagic DNA buffy coat kit (PerkinElmer, Germany) with Chemagic Magnatic Separation Module 1 and Chemagic Prime 8 Automated Workstation, and was subsequently bisulfite converted using the EZ-96DNA Methylation-Lightning^TMMagPrep from Zymo according to the manufacturer’s instructions. DNA methylation levels were measured on Illumina iScan using Illumina’s Human MethylationEPIC BeadChip. The methylation level for each probe was derived as a beta value representing the fractional level of DNA methylation at that probe. Sample-level and probe-level quality control was performed using the ‘minfi’ package [38 (link)] in R (version 3.5.0). Samples with sex mismatch or a missing rate at > 1% across all probes were excluded. Probes with a missing rate > 1% (at a detection p value > 0.01) were also excluded following previously published recommendation guidelines for analyzing methylation data [39 (link)].