[Congenital deficiency of factor Xii and spontaenous venous thrombosis treated with urokinase]

There is a well known relationship between factor XII deficiency and arterial and venous thrombosis. A new case of moderate factor XII deficiency associated to spontaneous deep vein thrombosis and treated with Urokinase is reported. The patient had a partial response to the treatment with Urokinase, with normal study of the fibrinolytic system. The deficiency was found in five relatives within the three generations studied. The genetic transmission had an autosomic dominant pattern. We feel that there is no relationship between the family history or the degree of factor XII deficiency and the risk of developing deep venous thrombosis.