Prothrombin G20210A

Prothrombin G20210A is a genetic variation associated with increased blood coagulation (thrombophilia). It increases the risk of blood clots including from deep vein thrombosis, and of pulmonary embolism. One copy of the mutation increases the risk of a blood clot from 1 in 1,000 per year to 2.5 in 1,000. Two copies increases the risk to up to 20 in 1,000 per year. Most people never develop a blood clot in their lifetimes.

It is due to a specific gene mutation in which a guanine is changed to an adenine at position 20210 of the DNA of the prothrombin gene. Other blood clotting pathway mutations that increase the risk of clots include factor V Leiden.

Prothrombin G20210A was identified in the 1990s. About 2% of Caucasians carry the variant, while it is less common in other populations. It is estimated to have originated in Caucasians about 24,000 years ago.