Congenital thrombophilia among patients with venous thromboembolism.

During a 3-year period we studied 393 adult patients (382 of whom were unrelated) with a history of acute venous thromboembolism. A congenital deficiency state known to predispose to thrombosis was found in 27.2%. Of these, most were due to deficiencies of protein C (9.2%), protein S (7.6%), antithrombin III (5%) or to increased plasma PAI-1 concentration (3.1%) which, in the absence of any known factor that predisposes towards thrombosis, results in a diminished fibrinolytic activity. There was a characteristic pattern between the age of onset (mean 34 years) of thrombosis and individual protein deficiency. Thrombosis appeared spontaneously in 73% of cases with recurrence in 80%. In contrast, in the remaining unrelated patients, 138 (35.1%) in whom venous thromboembolism was secondary and occurred at a mean age of 43 years, and in the other 140 (35.6%) who suffered thromboembolism spontaneously at a later age (mean age 55), there was no permanent protein deficiency state or alteration in fibrinolytic activity and thrombosis recurrence was lower (53.6% and 20.7% respectively). Of the 393 patients, deep vein thrombosis was the most common manifestation; however, in congenital thrombophilia, thrombosis of visceral vessels and Raynaud's syndrome (6%) were also detected.