PROS1 and thrombophilia: According to the American Society for Reproductive Medicine (ASRM), screening for inherited thrombophilias (specifically, factor V Leiden and prothrombin gene mutations, protein C, protein S, and antithrombin deficiencies) may be clinically justified when a patient has a personal history of venous thromboembolism in the setting of a non-recurrent risk factor (such as surgery) or a first-degree relative with a known or suspected high-risk thrombophilia.