Clinical and biological aspects of juvenile thrombophilia.

The clinical status of 418 consecutive thrombotic patients was assessed and they were investigated for deficiencies of the proteins involved in the modulation of blood coagulation and fibrinolysis. The whole cohort was divided into two groups according to the age at which the first thrombotic event occurred: group 1 younger than 45 years and group 2 older than 45 years. Deficiencies were significantly more frequent in the juvenile thrombotic population; in this subset of patients the prevalences of single deficiencies were: protein S (6.9%), protein C (4.9%), antithrombin III (3%), plasminogen (0.5%) and dysfibrinogenemia (0.3%). It was possible to diagnose 41 additional deficiencies in the relatives of the probands. The clinical picture and the presence, absence and type of predisposing factors were not statistically different in deficient and non-deficient patients. However, deficient patients experienced their first episode significantly earlier than non-deficient patients and had a significantly higher number of recurrences and pulmonary embolism episodes. From the analysis of the thrombosis-free survival curves, there is no doubt that age represents a strong cofactor in thrombotic risk-related deficiency.