Screening for aetiology of thrombophilia: a high prevalence of protein S abnormality

We systematically screened for the aetiology of thrombophilia in 115 patien ts with venous, arterial and small vessel thromboses. Forty-one patients (3 6% of those we examined) suffering from a variety of thromboses, including deep vein thrombosis, pulmonary embolism, arterial occlusion, cerebral infa rction, Moyamoya disease and ulcerative colitis, were characterized either with positive lupus anticoagulants or with decreased activities of protein S, protein C, antithrombin III and/or plasminogen. Eight mutation sites wer e confirmed in 11 thrombotic patients using gene analysis. Decreased protein S activity was found with a high incidence (23 out of 115 ) in Japanese patients who suffered from not only venous thrombosis but als o arterial and small vessel thrombosis. We emphasize here the important rol e of protein S in the pathogenesis of thrombosis in the Japanese population .