ABSTRACT
Antithrombin deficiency and dysfibrinogenemia, the inherited thrombophilias to be described, were discovered in studies of families in which several members were affected by venous thrombosis. In 1993, resistance to activated protein C, the most common cause of inherited thrombophilia, was discovered. In most cases, it results from a mutation of the factor V gene, resulting in an abnormal factor V protein, termed factor V Leiden. The most common inherited thrombophilias are heterozygosity for the Factor V Leiden (FVL) gene mutation, the prothrombin G20210A gene mutation, and the thermolabile variant of methylenetetrahydrofolate reductase, the most common cause of hyper-homocysteinemia. Carriers of multiple or homozygous thrombophilic defects were at increased risk of having a birthweight in the lowest quartile or lowest decile in a retrospective study. However, fetal FVL mutation carriage was associated with more frequent pre-eclampsia among African American women and Hispanic women compared to Caucasian women.
