We split the human sample into a discovery sample and replication sample consisting of N=6 and 5 women who would and N=12 and 9 who would not develop PPD, each with ~35% PPD to 65% non-PPD samples. In the discovery sample, we performed a probe-wise Student’s t-test between PPD and non-PPD cases. We cross-referenced genomic locations of the E2 DMRs from the mouse data with syntenic loci located on the human microarray (Figure 1b). Synteny was calculated based on the relative position of the implicated DMR (Mouse array) or individual CpG locus (Human array) from the closest proximal transcription start site within conserved sequence regions, as established by the UCSC Genome Browser Liftover tool. Owing to the nature of the enzymatic enrichment used in the mouse array experiment, a CpG locus was considered overlapping if it was adjacent within 200 bp of the implicated DMR. In total, 1578 human CpGs were located within the nominally significant mouse E2 DMRs. Pathway analysis of genes associated with overlapping loci using the g.Profiler analysis suite28 identified a single significant GO category (GO: 0010646,
