[Constitutional protein C deficiency in 57 patients from 22 non-related families]

A congenital deficiency in protein C (physiological inhibitor of coagulation) was identified in 57 patients: the deficiency was quantitative (type I) in 20 families, qualitative (type II) in two families. The transmission was autosomal dominant in 21 families but was suspected to be recessive in one family: the 18 years old homozygous propositus has a severe deficiency (protein C = 16 p. 100): both parents are heterozygous (consanguinity was present) and 5 other family members with heterozygous deficiency are asymptomatic. In the 49 patients (25 women, 24 men) belonging to the 21 other families, 9 men and 4 women (27 p.100) are asymptomatic although precipitating factors had existed in 5 patients. In the remaining 36 symptomatic patients, a deep venous thrombosis was observed in 34, a pulmonary embolism in 18. Recurrent arterial thromboses were diagnosed in 3 patients. The first thrombotic episode was observed at the mean age of 27 +/- 11 years and a triggering factor was found in 26 patients (72 p. 100). Thrombosis was recurrent in 21 (60 p. 100). In the patients without oral anticoagulant treatment, mean protein C antigen concentrations were 47 +/- 9 p. 100 and mean protein C activity was 46 +/- 10 p. 100. In 4 patients with type II deficiency, protein C antigen levels were normal (113 +/- 15 p. 100), contrasting with decreased protein C activity (43 +/- 6 p. 100). Thirty-eight patients have been treated with oral anticoagulants and a skin necrosis developed in the homozygous patients only.(ABSTRACT TRUNCATED AT 250 WORDS)