TTC9B (tetratricopeptide repeat domain 9B) is a gene whose DNA methylation status serves as a biomarker for postpartum depression (PPD) risk. While its direct molecular function remains unspecified in the provided literature, TTC9B methylation patterns are prospectively predictive of PPD development, with predictive models achieving 78-96% accuracy (AUC values) when combined with HP1BP3 methylation status 12. The gene's methylation profile correlates with estrogen-induced epigenetic reprogramming in the hippocampus, suggesting TTC9B participates in estrogen-mediated gene regulation related to synaptic plasticity 1. TTC9B methylation shows moderate association with changing estradiol and allopregnanolone levels during pregnancy, indicating the locus mediates hormonal sensitivity 3. Clinically, antenatal TTC9B DNA methylation assessment has potential as a diagnostic tool to identify pregnant women at future risk of PPD, enabling early clinical intervention in at-risk populations including military-affiliated women 24. The biomarker demonstrates PPD-specific age-related trajectories, possibly reflecting age-associated hormonal changes 3. TTC9B represents a promising epigenetic target for understanding PPD pathophysiology and developing precision prevention strategies.