Co-inhibitory receptors, including cytotoxic T-lymphocyte associated protein 4 (CTLA-4), programmed cell death protein 1 (PD-1), lymphocyte-activation protein 3 (Lag-3), and TIGIT play an essential role in the prevention of autoimmune disorders by promoting tolerized responses (151, 152). The gene discussed is CTLA4; the disease is Autoimmunity.