Fibrinolysis in patients with the 1691 G->A mutation in factor V gene and history of deep vein thrombosis

It was observed that cosegregation of two inherited risk factors for deep vein thrombosis (DVT), e.g. resistance to activated protein C (APC) with protein C or protein S deficiency increases clinical manifestation of DVT. The aim was to establish if there exists cosegregation of the 1691 G-->A mutation in factor V gene, the major cause of resistance to APC and impairment of fibrinolysis, and if possible cosegregation of both defects effects severity of the disease. Eighty-eight consecutive patients (37 females, 51 males, aged 19-60, mean 42 years) were investigated 18 +/- 10 months after acute DVT. In 15 patients (16%), the 1691 G-->A mutation in factor V gene was observed. These patients did not differ from other DVT patients by clinical characteristics, age, body mass index, fasting glucose and cholesterol, or by resting levels of tissue-type plasminogen activator (t-PA), plasminogen activator inhibitor 1 (PAI-1) and euglobulin activity (t-PA, antigen: 7.5 vs 7.1 ng/mL; t-PA activity: 0.9 vs 1.2 IU/mL; PAI-1 antigen: 18.1 vs 13.6 ng/mL; PAI activity 13.8 vs 13.9 IU/mL, all values medians; euglobulin clot lysis time: 308 +/- 32 vs 298 +/- 78 min, mean +/- SD). Moreover, frequencies of abnormal levels of t-PA, PAI-1 (t-PA antigen >13 ng/mL, t-PA activity <0.1 IU/mL, PAI-1 antigen >37 ng/mL, PAI activity >35 IU/mL) and euglobulin activity (euglobulin clot lysis time >410 min) were similar in both subgroups of patients. Recurrent DVT was not more frequent in patients with both defects: the 1691 G-->A mutation in factor V gene and impaired fibrinolysis. It was concluded that altered fibrinolysis is not an aggrevating factor for DVT in patients with the 1691 G-->A mutation in factor V gene.