FACTOR II (PROTHROMBIN) Mutation Study

A Factor II mutation analysis is a genetic test that detects the prothrombin (Factor II) G20210A variant, which raises prothrombin levels and increases risk of venous blood clots. Performed on blood or saliva, it’s used for unexplained thrombosis, recurrent pregnancy loss, or family history. Results inform clot-risk assessment and management decisions but don’t alone determine need for lifelong anticoagulation.

A factor II assay measures the level and functional activity of factor II (prothrombin) in blood. Using clot-based or antigen tests, it detects prothrombin deficiency, vitamin K deficiency, liver disease, or inherited coagulation disorders and helps evaluate bleeding or clotting risk. It also aids anticoagulation monitoring. Results are reported as activity percentage or concentration and compared with reference ranges.

The Factor II (prothrombin G20210A) mutation is uncommon. About 1–3% of people of European ancestry carry the variant; prevalence is much lower in African and Asian populations (generally under 1%). Heterozygous carriers are typical; homozygous individuals are very rare. Testing is recommended only with clinical indication such as personal or family thrombotic history.

To test for factor II (prothrombin) deficiency, start with coagulation screening—prothrombin time (PT) and activated partial thromboplastin time (aPTT). A prolonged PT (±aPTT) prompts a mixing study to distinguish deficiency from inhibitors. Confirm with a specific factor II activity assay and, if needed, a prothrombin antigen assay. Genetic testing of the F2 gene and evaluation for vitamin K deficiency or liver disease complete the workup.

Mutation analysis begins with a biological sample (blood, saliva, or tissue). DNA is extracted and specific regions are amplified by PCR or captured for sequencing. Techniques include Sanger sequencing for single genes and next‑generation sequencing for panels, exomes, or genomes; microarrays detect copy‑number changes. Bioinformatics pipelines call and annotate variants, which are then confirmed, classified for clinical significance, and discussed with genetic counseling.

Lavender (purple) top tube containing EDTA anticoagulant is used for prothrombin (Factor II) gene mutation testing because it preserves white-cell DNA for molecular analysis. Some laboratories also accept ACD (yellow top) or specialized DNA collection tubes, so always follow the specific laboratory’s sample‑collection instructions for proper handling and transport.