Thrombophilia and preeclampsia: the evidence so far.

The Role of Thrombophilias Pregnancy is a hypercoagulable state. The field of thrombophilia, the tendency to thrombosis, has been developed rapidly and has been linked to many aspects of pregnancy. Recently, it has been determined that severe pregnancy complications such as severe preeclampsia intrauterine growth retardation (IUGR), abruptio placentae, and intrauterine fetal death (IUFD) are associated with thrombophilia. Thrombophilias are inherited or acquired conditions that predispose an individual to thromboembolism. Deficiencies of protein S, C, and antithrombin are rare and each of them is found in approximately 3% of patients with thrombosis. Three important inherited thrombophilias were discovered, which are responsible of the majority of thromboembolic events in patients with no otherwise apparent risk for thrombosis. Resistance to activated protein C caused by an adenine 506 guanine (A506G) mutation in factor V (factor V Leiden) has been linked with an increased risk for venous thromboembolism. Heterozygosity for the factor V (FV) Leiden mutation is found in approximately 5% of the population and the mutation is responsible for 20% to 30% of venous thromboembolism events. A recently described guanine 20210 adenine mutation in prothrombin is associated with higher plasma prothrombin concentrations and increased risk for venous thromboembolism and cerebral vein thrombosis. Homozygosity for the cytosine 677 thymine (C677T) mutation in methylenetetrahydrofolate reductase (MTHFR) results in decreased synthesis of 5-methyltetrahydrofolate, the primary methyl donor in the conversion of homocysteine to methionine, and the resulting increase in plasma homocysteine concentrations is a risk factor for thrombosis. The mutation is responsible for reduced MTHFR activity and is the most frequent cause of mild hyperhomocystinemia and can be found in 5% to 15% of the population. Homocysteine is an independent risk Correspondence: Michael J. Kupferminc, MD, Department of Obstetrics and Gynecology, Lis Maternity Hospital, Tel Aviv Sourasky Medical Center, 6 Weizman Street, Tel Aviv 64239, Israel. E-mail: [email protected]. gov.il