Heterozygous for Prothrombin G20210A: the relative risk of venous thrombosis is about 3 to 4-fold that of the general population. Other conditions, either acquired or inherited, may act synergistically to increase an individual's thrombotic risk.
Homozygous for Prothrombin G20210A: This is a rare finding occurring roughly 1 in 10,000 people of European descent. It probably confers some degrees of hypercoagulability, but there are too few cases to date to calculate risk. The magnitude of the risk associated with homozygosity for this mutation has not been fully established but is likely to be greater than the 3 to 4-fold increased risk attributed to heterozygosity.