Our protein panel included neurosecretory protein VGF (VGF), LINGO1, CNTNAP4, NRXN3, NXPH1, PCSK1N, SERPINI1, CARTPT, GRIA4, NPTXR, and CBLN4, which all showed significant downregulation in the CSF of MDD in comparison to the controls in the discovery approach (Student’s t test, permutation-based FDR < 0.05). Here, PCSK1N is linked to major depressive disorder.