PROS1 and Venous thrombosis: Venous thrombosis occurs due to interaction of several genetic and acquired factors.1 The genetic factors include activated protein C resistance (APC-R), deficiency of anticoagulant proteins such as antithrombin (AT), protein C and protein S. Antiphospholipid antibodies (APL) are the commonest cause of acquired thrombophilia, among which lupus anticoagulants (LA) and β2 glycoprotein I dependent anticardiolipin antibodies (aCL) are clinically the most relevant.