After adjustment for smoking, traumatic life events, alcohol consumption, and family history of depression in model 1, the HAMD-24 score was positively correlated with IL-6 level (r = 0.043, P < 0.05), and negatively correlated with sgp130 and E2 levels (r = -0.063 and -0.048, respectively, both P < 0.05). This evidence concerns the gene IL6ST and major depressive disorder.