The IL-6 activity/bioavailability measure was associated with higher somatic symptoms of depression (β=1.09; 95% CI 0.30, 1.88; PFDR=0.01), fatigue (β=4.34; 95% CI 1.26, 7.42; PFDR=0.03), depression severity (β=3.06; 95% CI 0.71, 5.40; P=0.02), poorer quality of life (β=−0.07; 95% CI −0.13, −0.01; PFDR=0.045), and decreased psychomotor speed (β=−5.46; 95% CI −9.09, −1.84; PFDR=0.01),. This evidence concerns the gene IL6 and major depressive disorder.