(See also Overview of Thrombotic Disorders.)
Prothrombin (factor II) is a vitamin K-dependent precursor of thrombin, the terminal enzyme of the coagulation cascade (see figure Pathways in blood coagulation). A single nucleotide mutation in one (or, less commonly, both) of the prothrombin genes at position 20210 results in increased plasma prothrombin levels (with potentially increased thrombin generation) and increases the risk of venous thromboembolism.
The prevalence of the mutation ranges from < 1% to 6.5%, depending on the population studied.
The diagnosis is made by genetic analysis of the prothrombin 20210 gene using blood samples.
Anticoagulation with heparin or low molecular weight heparin, followed by warfarin, is used for venous thrombosis, or for prophylaxis in patients at increased thrombotic risk (eg, by immobilization, severe injury, or surgery).
It is probable, but not yet certain, that the direct oral anticoagulant (DOAC) inhibitors of either thrombin (dabigatran) or factor Xa (eg, rivaroxaban, apixaban) can be used in place of other anticoagulants for this disorder.