The diverse clinical phenotypes and varying thrombosis manifestations seen in thrombophilic families suggest that susceptibility to venous thrombosis arises from the interplay of multiple genetic factors, including the Leiden mutation in the factor V gene (FV R506Q) and the prothrombin (PT) 20210G/A mutation (Castoldi et al. 2000). This evidence concerns the gene F2 and deep vein thrombosis.