title: Discrimination between normal wildtype and carriers of coagulation factor V Leiden mutation by the activated protein C resistance test in the presence of factor V deficient plasma.
abstract: Blood samples from 104 patients with clinically suspected thrombophilia were analyzed for coagulation factor V Leiden mutation (1691, G-->A) by allele-specific polymerase chain reaction. In 86 individuals (82.7%), the mutation was not detectable, whereas 15 patients (14.4%) were heterozygous and three patients (2.9%) were homozygous for factor V Leiden mutation. Plasma samples from these individuals were also tested for functional resistance of coagulation factor V to activated protein C (activated protein C resistance). This test was performed on a Schnitger-Gross coagulometer using an activated partial thromboplastin time-based activated protein C resistance test modified by applying a 1 : 5 dilution with factor V-deficiency plasma. All the individuals negative for factor V Leiden mutation were also negative in the functional activated protein C resistance test. On the other hand, all patients carrying the mutation revealed pathologic results in the activated protein C resistance test. The cutoff value for the activated protein C resistance index (> or = 1.7 = negative) was determined by testing 31 male and female blood donors. One of them was heterozygous for factor V Leiden mutation and had an activated protein C resistance index of 1.4, whereas those without factor V Leiden mutation had an activated protein C resistance index of 1.9 +/- 0.1 (mean +/- SD). Patients with clinically suspected thrombophilia without factor V Leiden mutation had an activated protein C resistance index of 2.1 +/- 0.2 (mean +/- SD), whereas patients heterozygous for the mutation had an index of 1.5 +/- 0.1 (mean +/- SD). Within the group of patients carrying the mutation, the activated protein C resistance test even distinguished between heterozygous and three homozygous (activated protein C resistance 1.0 to 1.2) carriers. The data demonstrate that the activated protein C resistance test in the presence of factor V-deficiency plasma provides a clear-cut discrimination between normal wildtype and carriers of factor V Leiden mutation with a sensitivity and specificity of 100%. Verification of positive activated protein C resistance tests can be performed easily with a simple and reliable polymerase chain reaction protocol for the 1691, G-->A mutation.
authors.affiliation: Medizinisch-Diagnostisches Institut, Klinikum Karlsruhe gGmbH, Germany.
authors.forename: K H
authors.initials: KH
authors.lastname: Reuner
authors.forename: F
authors.initials: F
authors.lastname: Litfin
authors.forename: H
authors.initials: H
authors.lastname: Patscheke
mesh_terms: D001483:Base Sequence; D001780:Blood Coagulation Tests / Q000379:methods; D017931:DNA Primers / Q000235:genetics; D005165:Factor V / Q000235:genetics*; D005166:Factor V Deficiency / Q000097:blood / Q000175:diagnosis / Q000235:genetics*; D005260:Female; D006580:Genetic Carrier Screening; D005838:Genotype; D006720:Homozygote; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D011486:Protein C / Q000378:metabolism*; D012016:Reference Values; D013924:Thrombophlebitis / Q000097:blood / Q000235:genetics
chemical_list: D017931:DNA Primers; D011486:Protein C; C095381:factor V Leiden; D005165:Factor V