Factor V R2 DNA Analysis

CPT: 81400
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Test Details

Use

This test provides information about additional risk for venous thrombosis among individuals known to be heterozygous for factor V Leiden (one copy of mutation). This knowledge aids in prevention of venous thrombosis. Factor V Leiden is the most common genetic risk factor for venous thrombosis and pulmonary embolism. It is present in 5% of the Caucasian population and in 20% to 40% of individuals with a history of venous thromboembolism. Not all individuals who are heterozygous for factor V Leiden will experience a thrombotic event, and the factor V R2 DNA analysis identifies some individuals at risk. Factor V Leiden heterozygotes are at a sevenfold increased risk for venous thrombosis compared to the general population. Coexistence of the R2 polymorphism with factor V Leiden increases that risk by an additional threefold, leading to an increased risk of approximately 16-fold.

Limitations

This is not a diagnostic test. It assesses increased risk of venous thromboembolism due to the presence of the factor V R2 variant in individuals who are heterozygous for factor V Leiden. Not all individuals with factor V R2 and factor V Leiden will have a venous thrombosis event in their lifetimes. Test results should be used in conjunction with clinical observation and other lab results.

Methodology

Polymerase chain reaction (PCR) with restriction enzyme digestion and polyacrylamide gel electrophoresis

Specimen Requirements

Specimen

Whole blood

Volume

5 mL

Minimum Volume

0.5 mL (Note: This volume does not allow for repeat testing.)

Container

Lavender-top (EDTA) tube (preferred) or yellow-top (ACD) tube

Storage Instructions

Maintain specimen at room temperature or refrigerate. Stable at room temperature and refrigerated for seven days.

Causes for Rejection

Clotted whole blood samples if adequate DNA not obtained; incorrect specimen type; frozen whole blood specimens

Clinical Information

References

Alhenc-Gelas M, Nicaud V, Gandrille S, et al. The factor V gene A4070G mutation and the risk of venous thrombosis. Thromb Haemost.1999 Feb; 81(2):193-197.10063990
Castoldi E, Brugge JM, Nicolaes GA, Girelli D, Tans G, Rosing J. Impaired APC cofactor activity of factor V plays a major role in the APC resistance associated with the factor V Leiden (R506Q) and R2 (H1299R) mutations. Blood. 2004 Jun 1; 103(11):4173-4179. 14976057
Faioni EM, Castaman G, Asti D, Lussana F, Rodeghiero F. Association of factor V deficiency with factor V HR2. Haematologica. 2004 Feb; 89(2):195-200. 15003895
Faioni EM, Franchi F, Bucciarelli P, et al. Coinheritance of the HR2 haplotype in the factor V gene confers an increased risk of venous thromboembolism to carriers of factor V R506Q (factor V Leiden). Blood. 1999 Nov 1; 94(9):3062-3066. 10556190
Folsom A, Cushman M, Tsai MY, et al. A prospective study of venous thromboembolism in relation to factor V Leiden and related factors. Blood. 2002 Apr 15; 99(8):2720-2725.

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
503940 Factor V R2 DNA Analysis 503942 FV R2 DNA Analysis Result: 41103-3
503940 Factor V R2 DNA Analysis 503941 Methodology: 49549-9
503940 Factor V R2 DNA Analysis 503944 Interpretation: 35474-6
503940 Factor V R2 DNA Analysis 503945 Comment: N/A
503940 Factor V R2 DNA Analysis 503946 Factor V HR2 Haplotype N/A

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