Evaluation of a novel quantitative assay for factor V leiden (FVL)
Abstract number: PP-WE-144
Hickey1 K.P., Cooper1 P.C., Kitchen1 S.
11Coagulation, Royal Hallamshire Hospital, Sheffield, UK
How-to-cite Hickey KP, Cooper PC, Kitchen S. Evaluation of a novel quantitative assay for factor V leiden (FVL). Journal of Thrombosis and Haemostasis 2009; Volume 7, Supplement 2: Abstract PP-WE-144
Hemoclot Quanti V-L (Hyphen BioMed, France) is a clotting assay designed to measure FVL concentration in plasma via its resistance to activated protein C (APC). In the assay an excess of APC, factor II, fibrinogen and protein S is added to 1:20 plasma dilution with clotting trigged by the addition of FXa, phospholipids and calcium. All testing was performed on an ACL TOP analyser (IL). Within run precision was assessed by running a FVL absent (n = 10) and heterozygous (n = 6) plasma, generating coefficient of variation of 11.2% and 3.6% respectively. The two calibration curves performed produced r2 values of 0.999 and 0.994. FVL absent controls (n = 39) were classified using an established screening test (Diagen). Heterozygote (n = 33) and homozygous (n = 3) patients were classified using Roche Lightcycler. FVL absent subjects had mean FVL concentration of 3.6% (range 0.8–7.5%), heterozygotes mean 57% (range 31–81%) and homozygotes mean 131% (range 117–150%). Results were also compared to Coatest APC Resistance V (Chromogenix) in patient matched (PM) groups of FVL absent (n = 29), heterozygous (n = 13) and homozygous (n = 2). Quanti F-V FVL classification was unaffected by oral anticoagulants. There was no significant difference between the warfarinised (mean 57.4%) and non-warfarinised patients (mean 55.8%) in heterozygotes. Freeze-thawing of reagents produced an average change in samples (n = 8) %FVL of 10% when compared to fresh reagent, but left interpretation unaffected. Quanti F-V is an easy assay to perform demonstrating a strong differentiation between patient groups in the samples tested and compares well with the Coatest APC Resistance assay.
Table: Comparison of patient matched groups
|Patient Group||Quanti F-V|
|3.9 (0.8–7.5)||3.06 (2.46 - 3.77)|
|55 (31–68)||1.85 (1.63–2.10)|
|137 (125–150)||1.23 (1.19–1.27)|
Disclosure of interest: No conflict of interest.
To cite this abstract use the following format:
Journal of Thrombosis and Haemostasis 2007; Volume 5, Supplement 2: abstract number
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