After liver transplantation in children, a 50% decrease in the plasma concentrations of both protein C and antithrombin III and a 10-fold increase in plasminogen-activator inhibitor in the immediate post-operative period leads to an increased risk of thrombosis.[7] This may have contributed to the post-operative portal vein thrombosis in our case. This evidence concerns the gene SERPINB2 and Venous thrombosis.