Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0033036 (APC)
 10,214 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Activated protein C resistance (APCR) has proved to be a frequent finding in association with thrombosis. The majority of patients with APCR have been found to be homozygous or heterozygous for the polymorphic variant factor V Q506 (factor V Leiden; FVQ506). However a small number of patients have APCR as assessed by functional tests but do not possess the FVQ506 polymorphism. Some of these cases are due to the presence of a lupus type anticoagulant but in this report we demonstrate that the remainder are almost entirely (nine out of ten) associated with an elevated level of FVIIIc. Spiking experiments in normal patient plasma and venous occlusion tests demonstrated that elevation of the FVIIIc results in a reduced APCR ratio and shortening of the APTT. Variation in FVIIIc, in conjunction with other factors, may therefore explain the variable phenotype associated with FVQ506 and the phenomenon of thrombosis associated APCR in the absence of FVQ506. We conclude that FVIIIc as well as FVQ506 should be taken into account when assessing thrombotic risk. APCR, elevated FVIIIc and shortened APTT have all been previously identified with an increased risk of thrombosis. It follows that resistance to APC may arise from a number of factors and is in itself a risk factor for thrombosis. The net effect of these factors is assessed in the functional test for APCR and it may be premature therefore to replace functional tests for APCR with DNA analysis alone.
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PMID:The influence of factor VIII on measurement of activated protein C resistance. 903 55

To investigate whether resistance to activated protein C (APC resistance) because of a mutation in the factor V gene (factor V Leiden) leads to a decrease in life expectancy, we analyzed overall and cause-specific mortality in 171 parents whose offspring carried this mutation. Compared with the Dutch general population, and after adjustment for age, sex, and calendar period, we found no excess deaths in the parents (standardized mortality ratio [SMR], 1.0; 95% confidence interval [CI], 0.8 to 1.2). The cause-specific SMR for malignant neoplasms (1.0; 95% CI, 0.6 to 1.4), diseases of the circulatory system (1.0; 95% CI, 0.7 to 1.4), and cerebrovascular disease (1.0; 95% CI, 0.4 to 1.9) also did not differ from unity. The SMRs for diseases of the respiratory system (1.4; 95% CI, 0.6 to 2.6) and for ischemic heart diseases (1.1; 95% CI, 0.7 to 1.7) were slightly increased. Under the age of 45 years, there was a ninefold increase of dying from ischemic heart disease. Thromboembolic complications were mentioned only once (venous embolism or thrombosis) as an underlying ("primary") cause of death (SMR, 2.3; 95% CI, 0.1 to 13.0) and three times (pulmonary embolisms) as a contributing ("secondary") cause of death (SMR, 1.5; 95% CI, 0.3 to 4.4). We conclude that there is no major effect of APC resistance on life expectancy. Therefore, long-term anticoagulation in carriers of factor V Leiden, on the basis of the carrier state alone, is not indicated.
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PMID:Mortality and causes of death in families with the factor V Leiden mutation (resistance to activated protein C). 905 17

The activated protein C resistance (APC-R) ratios in 50 patients with steady state homozygous sickle cell (SS) disease and 59 healthy AA controls was measured. There was a significant reduction in median APC-R ratio in sickle cell disease compared to controls. 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. However, the raised levels of factor VIIIC in SS patients in this study may be contributing to increased resistance to APC, which in turn may contribute to the vaso-occlusive complications of SS disease.
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PMID:Activated protein C resistance in homozygous sickle cell disease. 907 31

Factor V antigen levels were measured in 40 patients with factor V deficiency (11 homozygous and 29 heterozygous), in 38 patients with factor V Leiden mutation (16 homozygous and 22 heterozygous) and in three patients with combined heterozygous factor V deficiency and heterozygous factor V Leiden mutation (so-called pseudohomozygosis for APC resistance). Twenty normal subjects of both sexes served as controls. Factor V antigen levels compared well with factor V activity in normal subjects and in all groups of patients. They were normal both in homozygous and heterozygous APC resistance patients. Factor V antigen determination may be useful for the diagnosis of pseudohomozygosis for APC resistance. These patients have a phenotypic picture similar to homozygous APC resistance, but show a factor V antigen level about half the normal value since they are compound heterozygotes for factor V deficiency and APC resistance. In contrast, homozygous patients for APC resistance show normal factor V activity and antigen levels.
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PMID:Factor V antigen levels in APC resistance, in factor V deficiency and in combined APC resistance and factor V deficiency (pseudohomozygosis for APC resistance). 919 22

As thrombosis of placental vessels may result in recurrent fetal loss, we analysed 39 consecutive women with recurrent fetal loss of unknown cause for activated protein C resistance. Factor V Leiden (FVL) mutation (19 cases) or APC resistance without FVL (nine cases) were found among these 39 women. Evaluation of 128 pregnancies in 19 patients with factor V Leiden mutation and 56 gestations in nine women with acquired APC resistance, revealed over 50% first-trimester abortions and 17% late abortions. Intra-uterine fetal death occurred in nine out of 19 FVL patients (47%). Only 34 of 184 gestations (18%) in hereditary or acquired APC-resistance women resulted in a live birth, with 11 of the 34 (32%) being premature deliveries. These data suggest that, in some patients with recurrent fetal loss, hereditary and acquired APC resistance are potential causes of vascular placental insufficiency.
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PMID:Activated protein C resistance can be associated with recurrent fetal loss. 920 98

We studied the prevalence of antithrombin III (AT III), protein C (PC) and protein S (PS) deficiencies and factor V Leiden mutation in thrombophilia in Taiwan. Eighty-five consecutive and unrelated patients with otherwise unexplained venous thrombophilia were studied. Both antigen and activity of inhibitors were determined using commercial kits (Stago), activated PC sensitivity ratio (APC SR) by Coatest (Chromogenix), and factor V mutation by polymerase chain reaction with sequence specific primer. Of 85 patients, 41 were male, 44 female, and mean age 49.4 years (17-82 years). None had factor V mutation, or APC SR of less than 2; 50 (58.8%) showed a deficiency of inhibitor proteins; 34 (68.0%) were hereditary, 16 (32.0%) non-hereditary; 3 had an AT III deficiency, 16 a PC deficiency, 28 a PS deficiency, and 3 a combined deficiency. Thirty-five were non-deficient without a known cause. The average age at the first thrombotic episode was 48.5 years (13-81 years). Thrombosis occurred spontaneously in 39 (78.0%) of 50 deficient patients. In conclusion, a relatively higher prevalence of AT III, PC and PS deficiency (59%), but no factor V Leiden mutation, was found in venous thrombophilic Chinese patients in Taiwan compared to that in western countries. Screening for inhibitor protein deficiency in Chinese thrombophilic patients is highly recommended.
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PMID:High prevalence of antithrombin III, protein C and protein S deficiency, but no factor V Leiden mutation in venous thrombophilic Chinese patients in Taiwan. 927 15

We compared the performance characteristics of a commercial dilute Russell's viper venom (DRVV)-based APC resistance assay (Gradipore PC Impedance Test) to a routinely utilized commercial APTT based assay (Coatest APC Resistance Assay). The DRVV based assay offers improved sensitivity and specificity for the factor V Leiden mutation. However, the routine use of both assays provides optimum reliability for diagnosis of genetic APC resistance. Our results suggest that when both tests are either positive or negative, DNA analysis is unnecessary. Interference by lupus anticoagulants is dramatically minimized by the phospholipid rich DRVV reagent used in the assay and it is insensitive to high factor VIII activity. Additionally, discrepant functional assay results allow identification of patients who may have an acquired APC resistant phenotype.
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PMID:The use of two different APC resistance assay systems provides optimal sensitivity and specificity for diagnosing genetic APC resistance. 928 90

A new factor V mutation associated with resistance to activated protein C and thrombosis (factor V Cambridge, Arg306-->Thr) was found in one patient from a carefully selected group of 17 patients with venous thrombosis and confirmed APC resistance in the absence of the common Gln506 mutation. The Arg306 mutation was also present in a first degree relative who also had APC resistance. Other potential causes of APC resistance, such as a mutation at the Arg679 site and the factor V HR2 haplotype, were excluded. Subsequent screening of 585 patients with venous thromboembolism and 226 blood donors did not show any other individual with this mutation. Factor VThr306 is the first description of a mutation affecting the Arg306 APC cleavage site and is the only mutation, other than factor V Leiden (Arg506-->Gln), that has been found in association with APC resistance. This finding confirms the physiologic importance of the Arg306 APC-cleavage site in the regulation of the prothrombinase complex. It also supports the concept that APC resistance and venous thrombosis can result from a variety of genetic mutations affecting critical sites in the factor V cofactor.
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PMID:Factor V Cambridge: a new mutation (Arg306-->Thr) associated with resistance to activated protein C. 945 42

We studied 172 Greek patients (72 men aged 44.0 +/- 16.7 years and 100 women aged 46.5 +/- 14.1 years) with an unexplained thrombophilic tendency. One hundred and four apparently healthy persons (63 men aged 34.2 +/- 10.0 years and 41 women aged 37.1 +/- 13.3 years) were included as a control group. We performed the activated protein C resistance (APC-r) test using a clotting test (Chromogenix kit), detection of factor V Leiden using polymerase chain reaction (PCR)-restriction fragment length polymorphisms and measurement of thrombin-antithrombin complexes (TAT) and prothrombin fragment 1 + 2 (F1 + 2) levels with an immunoenzymatic assay. The normal range for the APC-r test (> 2.12) was determined from the controls. The factor V Leiden mutation was found in 31.9% of all the patients tested, in 28.1% of the unrelated patients with documented thrombophilic tendency of unknown origin and in 4.8% of the healthy controls. The APC-r test had a sensitivity of 0.42 and a specificity of 0.91 for the detection of factor V Leiden. Furthermore, we found no significant difference in levels of TAT and F1 + 2 between patients with and without the mutation and there was no correlation between aPC-r values and levels of TAT and F1 + 2.
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PMID:Factor V Leiden in Greek thrombophilic patients: relationship with activated protein C resistance test and levels of thrombin-antithrombin complex and prothrombin fragment 1 + 2. 949 Dec 65

In a routine checkup the family history of an elite female mogul skier was found to contain an unusually high number of thrombotic incidents. This prompted us to do diagnostic thrombophilia studies, which revealed a resistance to activated protein C, a heterozygous factor V Leiden disorder. This is the first documented case of APC resistance in an elite female athlete. Since high performance sports are known to carry an increased risk of thrombogenesis, measures to avoid thrombosis or a thromboembolic event must be initiated in case of known APC resistance. Suitable measures are early anticoagulation during periods of immobilization, a single dose of low molecular weight heparin, leg muscle exercises for long distance flights, and avoidance of hemoconcentration with a sufficient oral fluid intake.
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PMID:APC resistance in an elite female athlete. 950 42


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