Quantitative or qualitative deficiency of either protein C or protein S may lead to thrombophilia, a tendency to develop thrombosis; (2) antithrombin, a serine protease inhibitor (serpin) that degrades the serine proteases: thrombin (factor IIa), factors IXa, Xa, XIa, and XIIa); (3) tissue factor pathway inhibitor (TFPI), it limits the action of tissue factor (TF). This evidence concerns the gene PROS1 and Venous thrombosis.