The most common defect was antithrombin deficiency found in 20 (10.9%) patients followed by Factor V Leiden in 9 (5%) (1 had homozygous state and 8 had heterozygous state), protein C deficiency in 6 (3.2%), protein S deficiency in 5 (2.7%), and prothrombin gene mutation in 5 (2.7%) cases. This evidence concerns the gene PROS1 and hereditary antithrombin deficiency.