Order to detect prothrombin G20210A variant.
- Patient Preparation
- Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).
- Specimen Preparation
- Transport 3 mL whole blood. (Min: 1 mL)
- Storage/Transport Temperature
- Unacceptable Conditions
- Plasma or serum; collection of specimen in sodium heparin tubes.
- Ambient: 72 hours; Refrigerated: 1 week; Frozen: Unacceptable
Characteristics: The Factor II, G20210A mutation is a common genetic risk factor for venous thrombosis associated with elevated prothrombin levels leading to increased rates of thrombin generation and excessive growth of fibrin clots. The expression of Factor II thrombophilia is impacted by coexisting genetic thrombophilic disorders, acquired thrombophilic disorders (eg, malignancy, hyperhomocysteinemia, high factor VIII levels), and circumstances including: pregnancy, oral contraceptive use, hormone replacement therapy, selective estrogen receptor modulators, travel, central venous catheters, surgery, and organ transplantation.
Incidence: Approximately 2-5 percent of Caucasians and 0.3 percent of African Americans are heterozygous; homozygosity occurs in 1 in 10,000 individuals.
Inheritance: Incomplete autosomal dominant.
Penetrance: The risk of thrombosis is increased 2-4 fold for heterozygotes and further increased for homozygotes.
Cause: Homozygosity or heterozygosity for F2 c.20210G>A (G20210A).
Mutation Tested:F2 c.20210G>A (G20210A).
Clinical Sensitivity for Venous Thrombosis: Approximately 10 percent.
Methodology: Polymerase chain reaction and fluorescence monitoring.
Analytical Sensitivity and Specificity: 99 percent.
Limitations:Diagnostic errors can occur due to rare sequence variations.F2 gene mutations, other than G20210A, will not be detected.
Counseling and informed consent are recommended for genetic testing. Consent forms are available online.
|Component Test Code*||Component Chart Name||LOINC|
|0056060||Prothrombin (F2) G20210A Mutation||24475-6|
|2001334||PT PCR Specimen||31208-2|
- F2 DNA assay
- Factor II (PT) 20210 Mutation (Prothrombin (F2) G20210A Mutation)