In particular, high serum concentrations of the soluble PD-1 (sPD-1), PD-L1 (sPD-L1), and CTLA-4 (sCTLA-4) have been associated with several autoimmune diseases (e.g., Graves’ disease, myasthenia gravis, systemic lupus erythematosus, type 1 diabetes, systemic sclerosis, coeliac disease, autoimmune pancreatitis, and primary biliary cirrhosis)18–20. The gene discussed is PDCD1; the disease is autoimmune disease.