Her basic screening for thrombophilia was normal: protein C, free protein S, AT, activated protein C (APC) resistance, lupus anticoagulant, FV Leiden, factor II (FII) G20210A mutation, fasting serum homocysteine, anticardiolipin antibodies, anti-beta-2 glycoprotein 1 (anti-b2 GP1) antibodies; however, she showed an AT activity of 51% (normal range 70–120%; chromogenic Liquid Antithrombin; Instrumentation Laboratory, Milano, Italy). This evidence concerns the gene PROS1 and thrombophilia.