Genetic factors associated with thrombosis in pregnancy in a United Statespopulation

OBJECTIVE: Polymorphisms in the genes for factor V (factor V Leiden), proth rombin, methylenetetrahydrofolate reductase, and angiotensin-converting enz yme have been associated with the occurrence of venous thrombosis. The obje ctive of this study was to determine the relationships of these polymorphis ms to thrombosis during pregnancy. STUDY DESIGN: This case-control study included 41 case patients with venous thrombosis during pregnancy and 76 control subjects matched for hospital a cid for race (white vs black) who had a normal pregnancy. RESULTS: Among white subjects, mutations in the genes for factor V and prot hrombin were associated with increased risks of venous thrombosis during pr egnancy (factor V: odds ratio, 18.3; 95% confidence interval, 2.7-432; P = .001;prothrombin: odds ratio P; 95% lower confidence limit, 1.7; P = .01). No black subject had either of these two mutations. For both black and whit e subjects the D/D genotype of the gene for angiotensin-converting enzyme e ntailed increased risk compared with the other genotypes (odds ratio, 2.7; 95% confidence interval, 1.2-6.3; P = .02). The polymorphism in the gene fo r methylenetetrahydrofolate reductase was unrelated to thrombosis during pr egnancy among both blacks and whites. CONCLUSION: Women who had thrombotic complications during pregnancy demonst rated an increased prevalence of genetic mutations related to coagulation. The additional risk of thrombosis during pregnancy associated with such gen etic mutations can be substantial.