Mean-scaled variability, measured as CVR, was significantly lower in patients with depression for CRP (CVR = 0.85; 95%CI: 0.75–0.98; p = 0.02); IL-12 (CVR = 0.61; 95%CI: 0.46–0.80; p < 0.01); and sIL-2R (CVR = 0.85; 95%CI: 0.73–0.99; p = 0.04), while it was unchanged for IL-3, IL-6, IL-18, and TNF α. This evidence concerns the gene IL18 and major depressive disorder.