Sign in →

Test ID: PTNT Prothrombin G20210A Mutation, Blood

Reporting Name

Prothrombin G20210A Mutation, B

Useful For

Direct variant analysis for the prothrombin (PT) G20210A allele in patients with clinically suspected thrombophilia

Specimen Type

Whole blood


Specimen Required


Container/Tube:

Preferred: Yellow top (ACD solution A or B)

Acceptable: Lavender top (EDTA) or light blue top (sodium citrate)

Specimen Volume: Full tube

Collection Instructions:

1. Invert several times to mix blood.

2. Send specimen in original tube.

Additional Information: Can be combined with other molecular coagulation tests:

-F5DNA / Factor V Leiden (R506Q) Mutation, Blood


Specimen Minimum Volume

1 mL in a 3-mL ACD tube

Specimen Stability Information

Specimen Type Temperature Time Special Container
Whole blood Ambient (preferred) 7 days
  Frozen  14 days
  Refrigerated  14 days

Reference Values

Negative

Day(s) and Time(s) Performed

Monday through Friday; 12 p.m.

Test Classification

This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.

CPT Code Information

81240-F2 (prothrombin, coagulation factor II) (eg, hereditary hypercoagulability) gene analysis, 20210G->A variant

 

LOINC Code Information

Test ID Test Order Name Order LOINC Value
PTNT Prothrombin G20210A Mutation, B 24475-6

 

Result ID Test Result Name Result LOINC Value
21803 Prothrombin G20210A Mutation, B 24475-6
21804 PTNT Interpretation 69049-5
21806 PTNT Reviewed By 18771-6

Clinical Information

Venous thromboembolism (VTE) is a syndrome of deep vein thrombosis and its complication, pulmonary embolism. The prothrombin (PT) G20210A variant (F2 rs1799963) is a common alteration within the 3' untranslated region of the prothrombin gene, affecting 1.5% to 3% of Caucasian Americans, especially persons of southern European ancestry. The PT G20210A allele is uncommon among African Americans (carrier frequency of 0.4%). The PT G20210A variant is associated with a 3-fold increased risk of VTE due to increased plasma prothrombin activity among carriers.

 

This test is a direct alteration analysis of patient blood leukocyte genomic DNA. At present, there are no other methods of detecting this VTE risk factor except for direct variant testing.

 

Direct variant analysis for the prothrombin (PT) G20210A allele should be reserved for patients with clinically suspected thrombophilia. There may be additional indications for direct PT G20210A mutation testing, such as in determining the duration of anticoagulation therapy of venous thromboembolism patients and screening for women contemplating hormone therapy.

Interpretation

The interpretive report will include sample information, assay information, background information, and conclusions drawn from the test results (normal, heterozygous prothrombin [PT] G20210A, homozygous PT G20210A).

Clinical Reference

1. Poort SR, Rosendaal FR, Reitsma PH, Bertina RM: A common genetic variation in the 3'untranslated region of the prothrombin gene is associated with elevated plasma prothrombin levels and an increase in venous thrombosis. Blood. 1996;10:3698-3703

2. Makris M, Preston FE, Beauchamp NJ, et al: Co-inheritance of the 20210 A allele of the prothrombin gene increases the risk of thrombosis in subjects with familial thrombophilia. Thromb Haemost. 1997;78:1426-1429

3. De Stefano V, Martinelli I, Mannucci PM, et al: The risk of recurrent venous thrombosis among heterozygous carriers of both factor V Leiden and the G20210A prothrombin mutation. N Engl J Med. 1999;341:801-806

4. Hall, JG et al: Sensitive detection of DNA polymorphisms by the serial invasive signal amplification reaction. Proc Natl Acad Sci USA. 2000;97:8272-8277

5. Heit JA: Thrombophilia: clinical and laboratory assessment and management. In: Kitchens CS, Alving BM, Kessler CM, eds. Consultative Hemostasis and Thrombosis. 2nd ed. Saunders; 2007:213-244

Analytic Time

3 days

Method Name

Direct Mutation Analysis

Forms

1. New York Clients-Informed consent is required. Document on the request form or electronic order that a copy is on file. The following documents are available in Special Instructions:

-Informed Consent for Genetic Testing (T576)

-Informed Consent for Genetic Testing-Spanish (T826)

2. Coagulation Patient Information (T675) in Special Instructions

3. If not ordering electronically, complete, print, and send a Coagulation Test Request (T753) with the specimen.