Predisposing variants of thrombophilia include antithrombin, protein C and protein S deficiency, prothrombin polymorphism, factor V Leiden mutation, antiphospholipid antibodies, hyper-homocysteinemia, pregnancy, puerperium, surgery, cancer, immobilization, oral contraceptives, and inflammatory bowel disease. The gene discussed is PROS1; the disease is thrombophilia.