Previously, Bot et al. (2015) [19] showed that the serum concentrations of 19 molecules differed between MDD patients without comorbid anxiety disorder(s) and controls, including five (cystatin-C, FABP (adipocyte), fetuin-A, IGFBP-5, and PPP) found here to be sex-dependent markers. Here, CST3 is linked to major depressive disorder.