Active protein C resistance in Behcet's disease.

Behcet's disease is a systemic condition of unknown cause characterized in 20 to 40% of cases by venous and/or arterial thrombosis that is not fully e xplained by the hemostasis disorders reported in the literature. The presen t study investigated resistance to activated protein C in 65 Behcet's disea se patients, 75 normal subjects, and 70 patients with a history of isolated thrombosis. The test used involved predilution in factor V-deficient plasm a. Activated protein C resistance was found in six Behcet's disease patient s (9.2%), eight normal subjects (10.6%), and 21 patients with isolated thro mbosis (30%). Of the 26 Behcet's disease patients (40%) with a history of t hrombosis, only one had activated protein C resistance. Activated protein C resistance does not explain the increased risk of thrombosis in Behcet's d isease patients.