Hereditary protein S deficiency: clinical manifestations.

To analyze the clinical manifestations of protein S deficiency, we evaluated 136 members of 12 families with the disorder. Seventy-one persons were found to be heterozygous for protein S deficiency, which is inherited as an autosomal dominant trait. Venous thrombotic events occurred in 39 patients (55%) and were recurrent in 77%. Most symptomatic patients had various combinations of deep venous thrombosis (74%), superficial thrombophlebitis (72%), and pulmonary embolism (38%), either in succession or simultaneously. On five occasions thrombosis was found at unusual sites, like the axillary, mesenteric, and cerebral veins. The age at the first thrombotic event ranged from 15 to 68 years (mean, 28 years), and at age 35 the probability to be still free of thrombosis was only 32%. Fifty-six percent of the thrombotic events were not preceded by a precipitating condition. In these respects protein S deficiency is similar to protein C deficiency.