Heterozygous for Factor V Leiden: the relative risk of venous thrombosis is about 4 to 5-fold that of the general population. Other conditions, either acquired or inherited, may act synergistically to increase an individual's thrombotic risk.
Homozygous for Factor V Leiden: the relative risk of venous thrombosis is between 10 to 70-fold that of the general population. Other conditions, either acquired or inherited, may act synergistically to increase an individual's thrombotic risk.