title: Investigation of genotype-dependent differences in factor V activity as well as response to activated protein C by application of different methods.
abstract: Coagulation factor V has been at the centre of investigation for several years. In addition to factor V Leiden, various other polymorphisms are becoming the object of interest. Different results have been published about the association of the HR2 haplotype with decreased factor V levels and with reduced response to activated protein C (APC). Due to the central position of factor V in the clotting process, its activity can be determined in both thromboplastin-based and activated partial thromboplastin time (aPTT)-based assays. A multitude of assays are known for the determination of APC response. The aim of our study was to investigate whether different methods disclose genotype-dependent differences in factor V activity as well as APC response. Three wild-type carriers, three carriers homozygous for the R2 allele (4070G), and three carriers homozygous for the G allele (2391G, 2663G, 2684G, 2863G) were investigated. For each individual plasma sample, the factor V activity was determined using 12 different reagent combinations of three different thromboplastins, three different aPTT reagents, and two different factor V deficient plasma sources. The determination of factor V activity in the thromboplastin system revealed differences between the genotypes. These differences were independent of the thromboplastin reagent and the factor V-deficient plasma. The aPTT system exhibited a dependency on the aPTT reagent and the factor V-deficient plasma. Analysis of APC response disclosed genomic differences in specific test systems only. One type of assay could be more appropriate than other types in dependence of the position of genomic variations. Therefore, the applied assay is an important influential factor in investigations of functional consequences of genomic variations.
authors.affiliation: Institute of Clinical Chemistry and Laboratory Medicine, Carl Gustav Carus Faculty of Medicine of the Dresden Technical University, Dresden, Germany. Gabriele.Siegert@mailbox.tu-dresden.de
authors.forename: G
authors.initials: G
authors.lastname: Siegert
authors.forename: H
authors.initials: H
authors.lastname: Kostka
authors.forename: E
authors.initials: E
authors.lastname: Kuhlisch
authors.forename: T
authors.initials: T
authors.lastname: Schwarz
authors.forename: S M
authors.initials: SM
authors.lastname: Schellong
authors.forename: W
authors.initials: W
authors.lastname: Jaross
mesh_terms: D000483:Alleles; D001780:Blood Coagulation Tests / Q000379:methods / Q000592:standards; D005165:Factor V / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology; D005838:Genotype; D006720:Homozygote; D006801:Humans; D007202:Indicators and Reagents / Q000494:pharmacology / Q000592:standards; D010314:Partial Thromboplastin Time; D020641:Polymorphism, Single Nucleotide; D011486:Protein C / Q000187:drug effects / Q000378:metabolism*; D011517:Prothrombin Time; D013925:Thromboplastin / Q000494:pharmacology
chemical_list: D007202:Indicators and Reagents; D011486:Protein C; D005165:Factor V; D013925:Thromboplastin