KLK8 and major depressive disorder: The study was performed in a subsample (n = 160) of individuals from an independent Danish clinical Psychosocial RIsk factors for Stress and MEntal disease (PRISME) cohort with a custom-made pyrosequencing assay targeting the promoter region of KLK8. Additionally, we tested the association between KLK8 DNAm levels in four independent methylomic cohorts with data on depression and depression-related phenotypes.