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Diagnostic Services

Genetics Lab


Thrombosis Risk DNA Panel

Factor V Leiden, MTHFR Thermolabile Variants, Prothrombin 20210G>A.

The factor V Leiden mutation is the most common cause of activated protein C (APC) resistance, and most common genetic risk factor for thrombosis. Approximately 3-8% of the population is heterozygous, and have an estimated 5-10 fold increased risk of thrombosis. Homozygotes have a 50-100 fold increased risk.

The c.677C>T MTHFR polymorphism is present in the homozygous form in 5-15% of the general population. Individuals who are compound heterozygous or homozygous for the c.677C>T MTHFR variant may have mild elevations in blood homocysteine levels, especially in the setting of inadequate folate intake. Elevated homocysteine is an independent risk factor for venous thromboembolism. Approximately 20% of the population is compound heterozygous for both MTHFR variants. Less is known about the thrombotic risk associated with c.1298 A>C. The c.677C>T variant is also associated with methotrexate toxicity.

The common prothrombin c.20210G>A mutation is associated with elevated prothrombin levels, which promotes development of fibrin clots. 2-4 % of the population is heterozygous for PTV 20210. Heterozygotes have an estimated 3-11 fold increased risk of thrombosis.

Test Name: Thrombosis Risk Panel
Test Code:
Test Description:
Multiplex PCR of the MTHFR, F2, and F5 genes.
MTHFR, Factor V Leiden, Prothrombin
This test is indicated for individuals with a history of venous thromboembolism (VTE) as part of thrombophilia work up.
Related Tests: Methylene Tetrahydrofolate Reductase, (677C>T, 1298A>C)  
Analysis of the MTHFR gene for two variants associated with mildly elevated homocysteine.

Factor V Leiden (p.R506Q)  
Analysis of the Factor V gene for the Leiden (R506Q) mutation.

Prothrombin variant (Factor II), mutation analysis (20210G>A)  
Analysis of the F2 gene for the 20210G>A mutation.

Clinical Links: Factor V Leiden Thrombophilia - GeneReview
Prothrombin-Related Thrombophilia - GeneReview
MTHFR Genetics Home Reference
Available weekly
Turnaround Time:
7 days
Reference Range:
Interpretive report will be provided
Consent Form:
Sample Requirements: Type
Blood: 1-3 ml EDTA (purple) tube. DNA: 5ug extracted DNA

Do not spin. Keep at room temperature.

Ship overnight at room temperature. Blood sample must be received within 3 days of collection.
Samples Received:
Monday - Friday 8am - 5pm PST
Special Considerations:
Three separate reports will be generated. Note that these tests can also be ordered individually.
Please e-mail Lab Client Services ( or call at 206-987-2617 with any billing questions
CPT Code:
Please e-mail Lab Client Services ( or call at 206-987-2617 with any billing questions