This case-control study examined the prevalence of a prothrombin gene mutation in the 3'-untranslated region (UTR) first reported by Poort et al in Dutch subjects with a history of venous thrombosis and in matched control subjects without a history of thrombosis. We tested the hypothesis that the presence of the 3'UTR prothrombin mutation would convey a higher risk of venous or arterial thrombosis and therefore would be found in a higher-than-normal percentage of subjects with a history of thrombosis. Our study included 100 subjects: 50 with a history of thrombosis (21 with venous thrombosis and 29 with arterial thrombosis, who had been recruited from an anticoagulation clinic) and 50 control subjects without a history of thrombosis. DNA from these subjects was analyzed by polymerase chain reaction and agarose gel electrophoresis. We found a statistically significant increase in the prevalence of the 3'UTR mutation in subjects with a history of venous thrombosis compared with subjects without thrombosis. The prevalence of the 3'UTR prothrombin mutation was 19% (4/21;3 heterozygous and 1 homozygous) in subjects with a history of venous thrombosis, 0% (0/29) in subjects with a history of arterial thrombosis, and 2% (1/50) in control subjects (P < .0245, by Fisher's exact test for comparison of subjects with versus those without a history of venous thrombosis). The G-->A mutation at nucleotide 20,210 in the 3'UTR was confirmed by direct DNA sequencing. The similar increased prevalence of the 3'UTR mutation in subjects with venous thrombosis in our population and in the Dutch population studied by Poort et al suggests that this mutation is an important risk factor for venous thrombosis in the general white population.

The Northwick Park Heart Study found that factor VII (FVII) activity was a risk factor for ischemic heart disease, and other studies based on indirect assays of activated factor VII (FVIIa) found an elevation of FVIIa postprandially. We hypothesized that postprandial elevation of FVIIa would produce intermittent activation of factor X to Xa and, subsequently, prothrombin to thrombin. We chose to study postprandial activation of coagulation with a new assay specific for FVIIa that uses soluble tissue factor and with a prothrombin fragment 1 + 2 (F1 + 2) assay to detect the activation of prothrombin by factor Xa. We fed a high-fat breakfast (30 g/m2) to 30 healthy volunteer subjects (30.8 +/- 9.8 years; range, 20 to 49 years) on no medication. Fasting blood samples were collected for FVIIa, FVII antigen (FVIIag). and F1 + 2 as well as triglycerides and total and HDL cholesterol. A significant difference was found between fasting (2.82 +/- 1.49 ng/mL. mean +/- SD) and 6-hour postprandial (3.45 +/- 2.08 ng/mL) FVIIa levels (P < .004); FVIIag did not change significantly (mean, 0.89 U/mL fasting and 0.90 U/mL at 6 hours). In contrast, F1 + 2 levels were slightly lower 6 hours postprandially than fasting (median, 0.39 versus 0.44 nmol/L, P < .02). Four-hour postprandial triglyceride levels correlated significantly (p = 0.51, P < .02) with 6-hour postprandial FVIIag but not with 6-hour postprandial FVIIa. Postprandial F1 + 2 levels (at 6 hours) correlated significantly (p = 0.39, P < .04) with fasting FVIIag levels but not with 6-hour postprandial FVIIa levels. Thus, the basal FVIIag level, in the fasting state, may be involved in control of the generation of F1 + 2. We found a postprandial increase in FVIIa levels after a dietary fat load but did not find a concomitant postprandial burst of activation of factor X and prothrombin as measured by F1 + 2. Further studies are to test whether postprandial FVIIa generation leads to enhanced activation of coagulation.