TPH2 and major depressive disorder: On multivariate analysis, the final model indicated that TPH2 rs7305115 AA (OR 0.33, 95% CI 0.22-0.99, P < 0.001), family history of suicide (OR 2.98, 95% CI 1.17-5.04, P < 0.001), negative life events half year ago (OR 6.64, 95% CI 2.48-11.04, P < 0.001) and hopelessness (OR 7.68, 95% CI 5.79-13.74, P < 0.001) were significantly associated with the suicide behaviors in MDD patients.