Inherited Risk Factors for Venous Thrombosis : A Single Institution Experience / 대한혈액학회지

ABSTRACT

BACKGROUND: Venous thromboembolism is a serious medical problem causing considerable morbidity and mortality. Risk factors of thrombosis are surgery, trauma, pregnancy, tumor, oral contraceptive as well as genetic risk factors (deficiencies of protein C, protein S, antithrombin III) though genetic risk factors were found in about 5 to 10% of cases. Recently, it is known that point mutations in the factor V gene and the prothrombin gene are common risk factors of idiopathic deep vein thrombosis (DVT) in Caucasian. But the frequency of these mutations in Asian population are reported lower than Caucasian's. We investigated the incidence of hereditary risk factors of venous thrombosis at single institution. METHOD: From April 1998 to June 1999, patients who were diagnosed as venous thromboembolism and under 50 years old were enrolled. All patients were requested for protein C, protein S (total, free), antithrombin III, APC resistance test, factor VIII activity, anticardiolipin antibody, lupus anticoagulant (LA), anti-beta2-glycoprotein-I (anti-beta2-GPI). Point mutations of factor V (Arg506->Gln, Arg306->Thr, Arg306->Gly, A4070G) and prothrombin G20210A allele mutation were checked by allele specific PCR amplification. RESULTS: Thirty-four patients (M:F=19:15, median age 38, 22-49) were diagnosed as DVT (7), pulmonary embolism with/without other site venous thrombosis (5/7), retinal vein occlusion (10), venous thrombosis of unusual site (5). Nine patients had past thrombosis history. One patient had familial DVT history. Thirteen patients had acquired risk factors of thrombosis. All the results of APC resistance test were within normal range. There was no single case of factor V mutations or prothrombin G20210A allele mutation. Three patients had positive anti-beta2-GPI and one patient had positive LA. We also found free protein S deficiency : 5/31, combined deficiency of free protein S and antithrombin III: 3/31. Twenty-five patients (73.5%) had elevated factor VIII (>150%). CONCLUSION: In this study, we couldn't detect factor V point mutations, prothrombin G20210A allele mutation in thromboembolic patients. But we found high prevalence of elevated factor VIII. Follow-up test for factor VIII and clinical observation for recurrent thrombosis are in progress.