In IgG4-RD patients, the numbers of CD4+CD25+Foxp3−expressing Treg cells are significantly higher in the affected tissues and peripheral blood in comparison to the cell count in patients with other autoimmune and nonautoimmune diseases [6, 11, 45, 46, 57, 60, 61]. The gene discussed is CD4; the disease is immunoglobulin G4-related sclerosing disease.