This study evaluated the clinical potential of three NET markers-myeloperoxidase (MPO)-DNA, neutrophil elastase (NE)-DNA, and citrullinated histones (citH3)-for diagnosing MDD and predicting treatment response.<h4>Methods</h4>Two independent clinical cohorts (Cohort 1: n=83; Cohort 2: n=60) and a chronic unpredictable mild stress (CUMS) mouse model were used. This evidence concerns the gene MPO and major depressive disorder.