Mutations
Factor II G20210A is a mutation of guanine (G) to adenine (A) at position 20210 of the Factor II gene which encodes the prothrombin (factor II) protein, one of the clotting factors in blood.
Normally, the prothrombin protein is produced to help the blood clot, and is produced in greater amounts after a blood vessel is damaged. This mutation in the factor II gene results in overproduction of the prothrombin protein. The increased prothrombin protein level leads to a hypercoagulable state, i.e., an increased tendency to form blood clots.
This G20210A mutation in the factor II gene is the second most common inherited hypercoagulability (prone to clotting) disorder among ethnic Europeans. The mutation was identified in Leiden in 1996.
Factor V Leiden (Factor V G1691A) is a mutation of guanine (G) to adenine (A) at position 1691 in the Factor V gene which encodes the factor V protein, one of the clotting factors in blood.
This mutation results in an arginine to glutamine substitution in the Factor V protein. The conformation of the mutated protein interferes with binding by another protein that inhibits the pro-clotting activity of factor V, leading to a hypercoagulable state, i.e., an increased tendency to form abnormal and potentially harmful blood clots.
Factor V Leiden is the most common inherited hypercoagulability (prone to clotting) disorder among ethnic Europeans. It is named after the Dutch city Leiden, where it was first identified in 1994.