To our knowledge, this is the first study that assessed possible associations between SNPs in the NR3C1, CRHR1, AVPR1B, SKA2 and FKBP5 genes and TESI or TWOSI in a large cohort of adult outpatients with depression and treated with tianeptine (a mu opioid receptor agonist). The gene discussed is FKBP5; the disease is major depressive disorder.