CTLA4-Ig has been used clinically for the effective treatment of rheumatoid arthritis (RA) and juvenile idiopathic arthritis, as reviewed in (54), and has been tested against allergen-induced airway inflammation (55), ulcerative colitis (56), systemic lupus erythematosus (SLE) (57, 58), and other autoimmune diseases, as reviewed in (59). The gene discussed is CTLA4; the disease is rheumatoid arthritis.