CTLA4 and endometriosis: One of the immune checkpoint molecules, cytotoxic T lymphocyte–associated antigen-4 (CTLA4), particularly its soluble form (sCTLA4), has been correlated with several autoimmune diseases, such as autoimmune thyroid disease, type 1 diabetes mellitus, and immune thrombocytopenia and has been linked with endometriosis-related infertility [23].