Previous studies have shown the upregulations of Th2 cytokines (interleukin (IL)-4, IL-5, IL-13, and IL-21) and the regulatory T cell-mediated cytokines (IL-10 and transforming growth factor-β) in IgG4-RD patients [22]. The gene discussed is IL21; the disease is immunoglobulin G4-related sclerosing disease.