title: Whole blood screening test for factor V Leiden using a Russell viper venom time-based assay.
abstract: Factor V Leiden (FVR506Q) is a genetic defect in the factor V (FV) molecule that confers resistance to proteolysis by activated protein C (APC) and is the most common abnormality detected in patients studied for hereditary thrombophilia. The initial screening test for this abnormality was a comparison of the activated partial thromboplastin time (APTT) in the presence and absence of APC, expressed as a ratio. But this has been shown to lack sensitivity for the FV mutation. Other clot-based screening tests, such as the modified APTT, using FV-deficient plasma, or the Russell viper venom (RVV) time assay have improved sensitivity. Eighty-seven samples were studied using the RVV-based assay. This assay was performed on platelet-poor plasma (PPP-RVV) and whole blood (WB-RVV). All samples were analyzed by polymerase chain reaction (PCR) for the FV Leiden defect: 77 were PCR negative; 10 were PCR positive. Using a threshold ratio of 1.8, all samples were correctly categorized in the PPP-RVV and the WB-RVV tests, showing an observed sensitivity and specificity of 1.0. These results suggest that an RVV-based assay using whole blood could be an effective screening test for this common abnormality.
authors.affiliation: Miriam Hospital, Providence, Rhode Island 02906, USA.
authors.forename: M S
authors.initials: MS
authors.lastname: Akhtar
authors.forename: A J
authors.initials: AJ
authors.lastname: Blair
authors.forename: T C
authors.initials: TC
authors.lastname: King
authors.forename: J D
authors.initials: JD
authors.lastname: Sweeney
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D007611:Aprotinin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005165:Factor V / Q000032:analysis* / Q000235:genetics; D005260:Female; D005343:Fibrinolytic Agents / Q000494:pharmacology; D005820:Genetic Testing; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D011237:Predictive Value of Tests; D011486:Protein C / Q000494:pharmacology; D011517:Prothrombin Time; D012680:Sensitivity and Specificity; D013927:Thrombosis / Q000175:diagnosis* / Q000235:genetics; D014914:Whole Blood Coagulation Time
chemical_list: D005343:Fibrinolytic Agents; D011486:Protein C; C095381:factor V Leiden; D005165:Factor V; D007611:Aprotinin