PROS1 and deep vein thrombosis: The main mechanisms underlying DVT involve increased fibrinogen and anticardiolipin antibodies, and deficiencies in antithrombin III, protein C, and protein S, as well as activation of the coagulation system leading to hypercoagulability.4 The prevalence of seasonal variations in DVT and pulmonary embolism has been a topic of investigation, with some studies reporting higher rates in winter compared to summer, although no consensus has yet been reached.