Therefore, we perform a meta-analysis of all eligible studies to compare the serum levels of 23 markers: tumour necrosis factor (TNF)-α, interferon (IFN)-γ, interleukin (IL)-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, IL-17, IL-18, IL-21, IL-22, IL-23, adiponectin, chemerin, omentin, visfatin, lipocalin-2, resistin, soluble E-selectin (sE-selectin), fibrinogen, and complement 3 (C3), between psoriasis patients and healthy controls. This evidence concerns the gene IL21 and psoriasis.