Several human monoclonal antibodies directed against immune checkpoints, including cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), program death protein 1 (PD-1), and programmed death-ligand 1 (PD-L1), have been implemented for cancer treatment in order to promote an effector T cell response to tumors. The gene discussed is CTLA4; the disease is cancer.