Carriership of Factor V Leiden and evolutionary selection advantage.

Historically, lethal exsanguinations and severe infections have been two major causes of maternal death. Gene mutations that lower the risk of profuse hemorrhage or severe infections would give a survival advantage. A single mutation of coagulation factor V, known as FV Leiden (FVL), can be such a beneficial mutation. FVL is common among Caucasians and today confers an increased risk of thromboembolism. However, the high prevalence of FVL (up to 15%) in the general population suggests that it has given an evolutionary advantage. In this review, we discuss possible mechanisms of the evolutionary survival advantage associated with FVL. In women, FVL confers lower risk of blood loss and profuse hemorrhage in association with delivery and improves the hemoglobin status. In addition, FVL carriers possibly have a survival advantage during sepsis. In conclusion, the high prevalence of FVL may be the result of one or more evolutionary selection advantages.