We attempted to ascertain the function of HP1BP3 and TTC9B loci bioinformatically by using the STRING database31 (Supplementary Figure 4) and by performing weighted gene coexpression network analysis21 against DNA methylation of the HP1BP3 CpG (cg21326881) and TTC9B CpG (cg00058938) as the target variables for correlation (Supplementary Figure 5). The resulting networks of HP1BP3- and TTC9B-coregulated genes were strikingly anticorrelated (Spearman’s ρ= −0.76, P=2.2×10−16), suggesting that HP1BP3 and TTC9B are coregulated (Supplementary Figure 5b). Resultantly, we limited networks to those demonstrating significant non-parametric correlation between module membership and correlation significance per group and identified two coregulated networks significantly associated across both genes (Module 1: HP1BP3 ρ=0.56, P=8.8×10−4, TTC9B ρ= −0.54, P=0.0015; Module 2: HP1BP ρ=0.45, P=0.0087, TTC9B ρ= −0.46, P=0.0081) (Supplementary Figures 5c and d). No significantly enriched pathways were identified by g.Profiler in Module 2; however, Module 1 contained a number of significantly enriched KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways that can be tied to the antidepressant functions of E2 in the hippocampus (Supplementary Table 5).
