The factor V Leiden variant, responsible for the phenomenon of activated protein C resistance, was found to be less frequent among British (0.06) and Swedish/Danish (0.15) protein C deficiency patients than previously reported in a Dutch study (0.19).
The level of antibodies to anionic phospholipids (PLa), a response to activated protein C (APC), and the presence for the mutation in the coagulation factor V gene causing APC resistance were studied.
Evidence against heterozygous coagulation factor V 1691 G-->A mutation with resistance to activated protein C being a risk factor for coronary artery disease and myocardial infarction.
Seventy women with thrombosis in pregnancy were investigated for the presence of APC resistance and the associated Arg506-Gln mutation in coagulation factor V. The mutation was found in 46% of the investigated women.
It is concluded that further standardization of the commercial method here evaluated is necessary before it can be widely adopted for the screening of APC resistance and prediction of the presence of factor V Leiden.
Laboratory tests revealed a pathologic activated protein C resistance and a reduced functional protein S. The underlying genetic defect was identified as a heterozygous coagulation factor V mutation.
We describe the first case of Budd-Chiari syndrome due to homozygosity for factor V Leiden resulting in resistance to activated protein C. This is now recognized as the most common procoagulant disorder, and may account for many cases of Budd-Chiari syndrome previously though to be idiopathic or due to a latent myeloproliferative disorder.
In the 5 years that have elapsed since initial identification of these individuals, resistance to activated protein C (APC resistance), which is associated with the factor V Leiden gene mutation, has emerged as an important and highly prevalent inherited thrombophilic risk factor.
A point mutation in coagulation factor V (factor V Leiden) results in resistance to activated protein C and probably represents the most common genetic risk factor for venous thrombosis.
Low prevalence of activated protein C resistance and coagulation factor VArg506 to Gln mutation among Japanese patients with various forms of thrombosis, and normal individuals.
A recently discovered mutation in coagulation factor V (Arg506-->Gln, referred to as factor V Leiden), which results in resistance to activated protein C, is found in approximately one fifth of patients with venous thromboembolism.
Of 554 patients for whom APC resistance data was available, 221 (39.9%) had low APC resistance ratios (< or = 2.4); of these only 97 (43.9%) were factor V Leiden-positive.
This reduction in APC-R ratio was not explained by (1) the presence of the factor V Leiden, found in only one of 165 patients with SS disease including those tested for APC-R, or (2) the presence of lupus anticoagulants.
The molecular basis of APC resistance is a single-point mutation (arginine506-glutamine) in the gene that encodes for coagulation factor V. This mutation results in a factor V molecule (factor V(Leiden)) that is less effectively downregulated by APC than is normal factor V. The gold standard for the detection of this defect is DNA analysis.
All three patients had resistance to activated protein C by coagulation assay and were determined to be heterozygous for Factor V Leiden by molecular analysis.