Prothrombin (Factor II) 20210 Gene Mutation

A genetic mutation causes increased plasma levels of prothrombin (factor II), predisposing to venous thrombosis.

(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 (VTE).

The prevalence of the mutation ranges from < 1% to 4%, depending on the population studied (1). The mutation is very rare in individuals of Asian or African descent (1).

The diagnosis is made by genetic analysis of the prothrombin 20210 gene using blood samples.