In a study involving 190 patients diagnosed with depression, excluding those with coexisting inflammatory diseases, compared to 100 healthy individuals, elevated serum levels of IL-17 and IL-23 along with decreased levels of IL-21 and IL-35, a cytokine that counterbalances IL-17 (Galecka et al. 2021), were observed. The gene discussed is IL17A; the disease is major depressive disorder.