CTLA4 and autoimmune disease: CTLA-4 Haploinsufficiency with Autoimmune Infiltration’ (CHAI) is characterized by lymphadenopathy and/or splenomegaly, autoimmune diseases including autoimmune cytopenias, type 1 diabetes, autoimmune thyroiditis, hepatitis, arthritis, and autoimmune skin disorders lymphocytic infiltration of multiple non-lymphoid organs (predominantly gut, lungs, and brain), recurrent respiratory tract infections, and a progressive loss of circulating B cells and/or immunoglobulin levels, and accumulate CD21lo B cells over time (128, 129).