Resistance to activated protein C caused by the factor VR506Q mutation is a common risk factor for venous thrombosis

In 1993, inherited resistance to activated protein C (APC) was described as a novel risk factor for venous thrombosis. APC-resistance is present in 20-60% of venous thrombosis cases. It is caused by a single point mutation in the factor V gene which substitutes arginine (R) at position 506 with a glutamine (Q). The mutation is common in Caucasians with up to 15% prevalence in the population, whereas it is not found among other human races. Mutated factor V (FVR506Q, FV:Q506 or FV Leiden) is partially resistant to APC which results in a hypercoagulable state conferring a life-long increased risk of thrombosis. Individuals having FV:Q506 combined with other anticoagulant defects have a high risk of thrombosis, and it is now generally accepted that severe thrombophilia is a multigenetic disease. Easy functional and genetic tests for inherited APC-resistance will profoundly influence the development of prophylactic regimens and hopefully result in a decreased incidence of thrombosis.     

Genetic susceptibility to pregnancy-related venous thromboembolism: roles of factor V Leiden, prothrombin G20210A, and methylenetetrahydrofolate reductase C677T mutations

OBJECTIVE: This study's objective was to evaluate the association between venous thromboembolism during pregnancy and the postpartum period and the factor V Arg 506 Gln (factor V Leiden), the prothrombin G20210A, and methylenetetrahydrofolate reductase C677T polymorphisms. STUDY DESIGN: In this case-control study 42 case patients and 213 control subjects (parous age-matched women without history of thrombosis) were genotyped for all the polymorphisms. Moreover, antiphospholipid antibodies and protein C, protein S, and antithrombin III deficiencies were investigated in each case. RESULTS: Ten case patients (23.8%) and 4 control subjects (1.9%; odds ratio 16.3, 95% confidence interval 4.8-54.9) carried the factor V Leiden mutation; 13 case patients (31.0%) and 9 control subjects (4.2%; odds ratio 10.2, 95% confidence interval 4.0-25.9) were carriers of the prothrombin G20210A allele. Finally, 12 case patients (28.6%) and 34 control subjects (16.0%; odds ratio 2.1, 95% confidence interval 1.0-4.5) were homozygotes for methylenetetrahydrofolate reductase C677T. Overall, mutations were found in 25 case patients (59.5%) and 47 control patients (22.2%; odds ratio 5.2, 95% confidence interval 4.9-19.6). One patient carried the antithrombin III deficiency and 1 the protein S deficiency, whereas 2 women had a primary antiphospholipid syndrome. CONCLUSIONS: The significant risk estimates of having a pregnancy-related venous thromboembolism in the presence of the prothrombotic genetic risk factors analyzed suggest to screen for these mutations women with a personal history of thromboembolic events during pregnancy or the postpartum period.     

Activated protein C resistance--a recently discovered hereditary thrombophilia

Activated protein C resistance is an inherited thrombophilia caused by a point mutation in the factor V gene (G to A transition in nucleotide 1691 in the factor V gene with replacement of arginine (R) 506 by glutamine (Q) in the factor V molecule). The mutation is commonly named factor V R506Q or factor V Leiden. The mutation results in a poor anticoagulant response to activated protein C. APC resistance is inherited autosomally, and approximately 5-10% of the Norwegian population are carriers of the mutation. It is present in 20-50% of all cases of venous thromboembolism. Among asymptomatic heterozygous family members of affected individuals there is a five to eight-fold increase in the risk of venous thromboembolism, whereas there may be a 100-fold increased risk among homozygous individuals. The risk for asymptomatic carriers without a family history is yet not known. Activated protein C resistance is a major risk factor for venous thromboembolism, and the detection of activated protein C resistance is vital for proper prophylaxis and treatment of this disorder. It is essential therefore that as many medical specialists as possible acquire knowledge of activated protein C resistance. This report describes a family with activated protein C resistance and the main indications for screening for inherited thrombophilia.     

Study of the prothrombin gene 20201 GA variant in FV:Q506 carriers in relationship to the presence or absence of juvenile venous thromboembolism

The G20210A transition of the prothrombin gene has been identified as a common but probably mild hereditary risk factor for venous thromboembolism (VTE). However, the prothrombin gene variant might contribute to the penetrance of thromboembolic disease in many patients with other prothrombotic defects, such as the FV:R506Q mutation. In this investigation, the A20210 allele was found in 9 of 450 healthy controls (2%). Among 89 asymptomatic FV:Q506 carriers, 3 subjects were doubly affected (3.4%). In contrast, of 263 unrelated carriers of the FV:Q506 mutant with a history of juvenile VTE, 30 also had the prothrombin gene G20210A variant (11.4%), including 25 of 220 patients who were heterozygous (11.4%) and 5 of 43 homozygous (11.6%) for FV:Q506. Thus, the A20210 allele of the prothrombin gene is significantly overrepresented in symptomatic FV:Q506 carriers compared with healthy controls (P<0.0001) and asymptomatic relatives carrying the FV mutant (P=0.02). Persons homozygous for the 20210A allele were not found. A statistically significant increase in the prevalence of more unusual sites of venous thrombosis at clinical onset was found in doubly affected patients (9 of 30; 30%) compared with patients without the prothrombin gene variant (26 of 233; 11. 1%) (P=0.004). First VTE occurred spontaneously in 53.3% of all doubly affected patients (16 of 30) and in 28.3% of all simply affected patients (66 of 233) (P=0.005). Among patients with VTE preceded by circumstantial risk factors, the A20210 allele was found in 7.7% (14 of 181). We conclude that the A20210 allele of the prothrombin gene is frequently coinherited in symptomatic FV:Q506 carriers and possibly influences age, site, and type of thrombotic onset manifestation in these patients.     

A common mutation in the methylenetetrahydrofolate reductase gene (C677T) increases the risk for deep-vein thrombosis in patients with mutant factor V (factor V:Q506)

Hyperhomocysteinemia is a frequent risk factor for deep-vein thrombosis. A common mutation (C677T) in the gene encoding for methylenetetrahydrofolate reductase (MTHFR) is responsible, in the homozygous state, for decreased enzyme activity and mild hyperhomocysteinemia and is associated with increased risk for cardiovascular disease. We studied the prevalence of C677T MTHFR in 77 patients with deep-vein thrombosis and in 154 age- and sex-matched healthy control subjects. In the same individuals, we also evaluated the frequency of the coexistence of C677T MTHFR with mutant factor V:Q506, a common risk factor for deep-vein thrombosis. Sixteen patients (20.8%) and 35 control subjects (22.7%) were homozygous for the C677T MTHFR mutation (odds ratio [OR] = 0.8, 95% confidence interval [CI] = 0.4-2.0). Sixteen patients (20.8%) and 4 control subjects (2.6%) had factor V:Q506; of them, 10 patients and 3 control subjects had isolated factor V:Q506 (adjusted OR = 6.3, 95% CI = 1.6-25.3) and 6 patients and 1 control subject also had C677T MTHFR (adjusted OR = 17.3, 95% CI = 2.0-152.9). The OR for the coexistence of the two mutations was 65% to 75% higher than the expected joint effect calculated by either an additive (OR = 6.0) or multiplicative (OR = 4.4) model. The homozygous C677T mutation of MTHFR per se is not a risk factor for deep-vein thrombosis but increases the risk associated with factor V:Q506. Due to the high prevalence of C677T MTHFR, it is likely that previous studies, which did not look for this mutation, overestimated the relative risk of thrombosis associated with factor V:Q506 alone.     

Factor V Leiden and genetic defects of thrombophilia in childhood porencephaly

AIMS: To determine to what extent the Arg506 to Gln point mutation in the factor V gene and further genetic factors of thrombophilia affect the risk of porencephaly in neonates and infants. METHODS: The Arg506 to Gln mutation, factor V, protein C, protein S, antithrombin, antiphospholipid antibodies and lipoprotein (a) (Lp(a)) were retrospectively measured in neonates and children with porencephaly (n = 24). RESULTS: Genetic risk factors for thrombophilia were diagnosed in 16 of these 24 patients: heterozygous factor V Leiden (n = 3); protein C deficiency type I (n = 6); increased Lp (a) (n = 3); and protein S type I deficiency (n = 1). Three of the 16 infants had two genetic risk factors of thrombophilia: factor V Leiden mutation combined with increased familial Lp (a) was found in two, and factor V Leiden mutation with protein S deficiency type I in one. CONCLUSIONS: The findings indicate that deficiencies in the protein C anticoagulant pathway have an important role in the aetiology of congenital porencephaly.     

Axonal regeneration through muscle autografts submitted to local anaesthetic pretreatment

Over a 3 year period the R506Q mutation in the factor V (FV) FV:Q506 gene, FV, factor XII (FXII), prothrombin, protein C, protein S, antithrombin, heparin cofactor II, anticardiolipin antibodies and lipoprotein (a) (Lp(a)) were measured in 32 infants and children with sinus thrombosis. Heterozygous FV:Q506 (n=5), homozygous FV:Q506 (n=2), homozygous FXII deficiency (n=1), protein C deficiency type I (n=5), protein C deficiency type II (n=1), antithrombin deficiency type I (n=1) increased Lp (a) (n=5), activated protein C-resistance without mutation in the FV gene (n=2), and increased anticardiolipin IgG antibodies (n=2) were diagnosed in the children investigated. In a further two patients we found combinations of increased Lp(a) with moderate hyperhomocystinaemia and heterozygous plasminogen deficiency with heterozygous FXII deficiency. In addition, increased anticardiolipin IgG antibodies were found in combination with heterozygous FV:Q506 (n=1) and protein C type I deficiency (n=2) respectively. Out of 32 patients with venous sinus thrombosis, 3 showed additional peripheral venous vascular occlusion. Contributing factors were present in 31 out of 32 patients investigated. Family members of 10 affected children had suffered from venous thrombo-embolism prior to the study. CONCLUSION: Our data suggest that additional contributing factors may promote manifestation of cerebral venous sinus thrombosis in infants and children with an inherited prothrombotic state. Further prospective studies are required to evaluate their potential role as "triggering" agents.     

Risk of venous thromboembolism and stroke associated with oral contraceptives. Role of congenital thrombophilias

To assess the risk of thromboembolism in women using oral contraceptives (OCs), we identified through computer search in the hospitals of the province of Parma, Italy, all women aged 15-44 who were resident in the province and had a documented thromboembolic event in the years 1989-93. The number of users and nonusers of OCs was estimated by the drug sale data for the province and by the demographic statistics. In cases with venous thromboembolism (VT) the prevalence of concomitant deficiency of antithrombin III, protein C, protein S, and of factor V gene mutation Arg506GIn was evaluated. The incidence rate of VT was 37/59,603 woman-years in users (0.62 per 1000) and 13/303,954 woman-years in nonusers (0.042 per 1000), for a relative risk (RR) of 14.5 (95% confidence interval: 7.8-27.1; P < 0.001); the rate of stroke per 1000 woman-years was 0.17 in users and 0.036 in nonusers (RR = 4.6; 2.9-10.7; P < 0.01). A congenital thrombophilia involving the protein C anticoagulant system was documented in about 25% of young women developing venous thromboembolism while on OCs.     

Angiographic embolization of intrahepatic arterioportal fistula

BACKGROUND: Patients with venous thromboembolic disease may present with different clinical manifestations. Factor V Leiden mutation leading to resistance to activated protein C is associated with a sevenfold increased risk for presenting with deep-vein thrombosis. It is not yet established whether carriers of the mutation have a similarly increased risk for manifesting with pulmonary embolism. METHODS: From an Anticoagulation Clinic monitoring coumarin therapy, a consecutive series of patients with a first thromboembolic event (objectively proven by current radiological methods) were enrolled. All patients were interviewed and blood was drawn for genotyping. From the hospital charts and the personal interview, information was obtained on acquired risk factors and the signs and symptoms on hospital admission. RESULTS: 45 patients presented with symptoms of pulmonary embolism only, 211 had only symptoms of deep-vein thrombosis whereas 23 had clinical features of both. In about half of the patients acquired risk factors for venous thromboembolism were present which did not differ between the three groups of patients. Recent surgery had been performed more often in patients presenting with pulmonary embolism than in other patients (33.3% vs. 18.5%, p < 0.05). Factor V Leiden was present in 9% of the patients presenting with pulmonary embolism (relative risk: 3.3 95% CI: 1.0-10.6) and 17% of the patients presenting with deep-vein thrombosis (relative risk: 6.9 95% CI: 3.6-12.8). The prevalence of factor V Leiden was intermediate in patients with both clinical characteristics. CONCLUSION: These data suggest that patients with venous thromboembolism have different clinical presentation depending on the risk factor profile. Factor V Leiden may preferentially lead to manifest deep-vein thrombosis. Differences in structure of venous thrombi could underlie differences in embolic tendency.     

Risk of venous thromboembolism associated with a G to A transition at position 20210 in the 3'-untranslated region of the prothrombin gene

The odds ratio for the FII 20210G/A mutation in 504 patients with venous thromboembolism compared to controls was 2.0 (95% CI 1.0-4.0) and, for factor V Leiden, 5.8 (95% CI 3.3-10.3). 3/504 patients were heterozygous for both mutations. None of the patients had combined natural anticoagulant deficiency and the FII 20210G/A mutation. We conclude that the FII 20210G/A mutation is present in 2.6% of the population and the relative risk of venous thromboembolism in carriers is 2.0.     

Thromboembolic disease developing during oral contraceptive therapy in young females with antiphospholipid antibodies

The role of oral contraceptives as a triggering factor for thrombosis in patients with lupus anticoagulant (LA) and/or anticardiolipin antibodies (ACA) has not yet been established. We describe the cases of three women aged 19, 29 and 48 years who developed venous thrombosis after 16 +/- 3.4 (mean +/- SD) cycles of oral contraceptives. They were all asymptomatic before taking the pill. Two patients subsequently developed venous and/or arterial recurrence of thrombosis. Laboratory studies performed after the diagnosis of thrombosis, showed the presence of LA and elevated levels of ACA (IgG and IgM) in all three patients. None of these patients had autoimmune diseases and therefore appeared to have a primary antiphospholipid antibody syndrome. The three patients belonged to a group of 45 young females who experienced their first thrombotic event while taking the pill. This group had a similar prevalence (8%) for antithrombin deficiency and antiphospholipid antibodies. We surmise that some of the women who developed venous thrombosis while taking the pill might have an undetected primary antiphospholipid syndrome.     

Anticoagulant response to Agkistrodon contortrix venom (ACV test): a new global test to screen for defects in the anticoagulant protein C pathway

As specific assays used to identify defects in the protein C (PC) anticoagulant pathway are laborious and expensive, we describe here a global test to screen for these defects. This assay is expressed as the ratio of two activated partial thromboplastin times, one in the absence and one in the presence of 0,125 U/ml of the PC activator of Agkistrodon contortrix venom (ACV). Eight of the 168 healthy volunteers of the control group exhibited an ACV ratio below the lower normal limit of 3.37 [6 subjects with the mutation Arg 506 to Gln in their factor V gene (FV R506Q) and one with PS deficiency]. 128 patients who have had at least one episode of deep-vein thrombosis were retrospectively studied. All patients carrying FV Q506R (n = 48), PC deficiency (n = 14) or combined defects, i.e. FV Q506R and PC deficiency (n = 4) or FV Q506R and PS deficiency (n = 3), had ACV ratios < 3.37. PS deficient plasmas (n = 20) exhibited ACV ratios which overlapped normal range. ACV ratios of one out of seven patients with antithrombin deficiency, and 10% of patients without identified defect in the PC anticoagulant pathway (n = 30) were < 3.37. An ACV ratio raised to 3.70 could lead to a test identifying all patients with a defect in the PC anticoagulant pathway.     

Doppler-derived left ventricular rate of pressure rise and inotropic requirements during mitral valve surgery

OBJECTIVE: Inherited resistance to activated protein C (APC resistance), which is caused by a single point mutation in the factor V gene, is a frequent risk factor for venous thromboembolism. The aim of this study was to determine the prevalence of APC resistance and other coagulation disorders in fertile women with venous thromboembolism and also the risk factors these women had been exposed to in connection with thromboembolic events. DESIGN: A retrospective, case-control study of 36 month duration. SETTING: The study was carried out at Blekinge Hospital, Karlskrona, Sweden. SUBJECTS: The study population comprised 27 fertile women age 16-47 years with thromboembolic complications, referred to the department of Internal Medicine at Blekinge Hospital in Karlskrona during a 36-month period. RESULTS: APC resistance was found in 10 out of 27 women. APC resistance was associated with treatment with oral contraceptives in five out of six women and with pregnancy in one of seven women. All women with resistance to APC developed venous thrombosis in association with a predisposing situation (risk situation) such as surgery, trauma, immobilization, pregnancy, inflammatory state or the use of oral contraceptives. Amongst women not resistant to APC, all but one developed thrombosis in connection with a risk situation. CONCLUSION: APC resistance was found to be highly prevalent amongst fertile women with a history of thromboembolic complication occurring during their use of oral contraceptives.     

Thromboembolism and resistance to activated protein C in children with underlying cardiac disease

OBJECTIVES: In the majority of cases, resistance to activated protein C is caused by the point mutation Arg506 to Gln in the factor V gene and has emerged as the most important hereditary cause of thromboembolism. METHODS: To determine to what extent resistance to activated protein C was present in children with thromboembolism and underlying cardiac disease, its occurrence was retrospectively investigated. By using a method based on activated partial thromboplastin time, with DNA technique derived from the polymerase chain reaction, we investigated nine children with underlying cardiac disease in whom thromboembolism had previously occurred. RESULTS: Heterozygous Arg506-to-Gln mutation in the factor V gene was diagnosed in five of the nine children investigated. In addition, protein C type I deficiency w as found in three patients, and two of the nine children showed increased lipoprotein (a) plasma values. Risk factors were present in all children with symptoms. CONCLUSIONS: These data indicate that deficiencies in the protein C anticoagulant pathway are likely to play an important role in the early manifestation of thromboembolism in children with underlying cardiac disease.     

Risk factors for deep venous thrombosis of the upper extremities

BACKGROUND: Hypercoagulable states and triggering factors (surgery, trauma, immobilization, pregnancy, and use of oral contraceptives) are associated with an increased risk for deep venous thrombosis of the lower extremities. In contrast, risk factors for deep venous thrombosis of the upper extremities have not been identified. OBJECTIVE: To evaluate the prevalence of hypercoagulable states and triggering factors in patients with primary deep venous thrombosis of the upper extremities. DESIGN: Frequency-matched case-control study. SETTING: Hemophilia and thrombosis center at a university hospital. PATIENTS: 36 patients who had primary deep venous thrombosis of the upper extremities, 121 patients who had primary deep venous thrombosis of the lower extremities, and 108 healthy controls. Patients who had deep venous thrombosis of the lower extremities and study controls were frequency-matched by age, sex, geographic origin, and social status with patients who had deep venous thrombosis of the upper extremities. MEASUREMENTS: Resistance to activated protein C was evaluated by a clotting method based on the activated partial thromboplastin time. If test results were abnormal or borderline, DNA analysis for substitution in coagulation factor V gene was done. Antithrombin, protein C, protein S, antiphospholipid antibodies, and total plasma homocysteine levels were also measured. RESULTS: Prevalences of abnormalities of the natural anticoagulant system (9%) and hyperhomocysteinemia (6%) in patients who had deep venous thrombosis of the upper extremities were similar to prevalences of both factors in controls (6% and 7%, respectively) but lower than in patients who had deep venous thrombosis of the lower extremities (31% and 14%, respectively). Antiphospholipid antibodies were found only in patients who had venous thrombosis of the lower extremities (7%). The overall prevalence of hypercoagulable states in patients who had thrombosis of the upper extremities (15%) was similar to that in controls (12%) but was significantly lower than that in patients who had thrombosis of the lower extremities (56%). A recent history of strenuous exercise of muscles in the affected extremity was the most frequent triggering factor for patients who had deep venous thrombosis in the upper extremities (33%). CONCLUSIONS: This preliminary study indicates that the prevalence of hypercoagulable states is low in patients who have primary deep venous thrombosis of the upper extremities.     

Inherited prethrombotic disorders and infectious purpura

Patients with severe meningococcal infection are characterized by extensive microvascular thrombosis, consumption coagulopathy and secondary hemorrhages. The contribution of the inherited prethrombotic disorders to the severity of the disease course is not established yet. Here, we report on the levels of protein C, protein S, antithrombin and the presence of the factor V Leiden mutation (R506Q) in 50 patients with meningococcal disease, as determined 6 to 58 months after hospital discharge. In addition, we recalled the parents of 16 deceased patients to screen for the mutation in factor V, an abnormality which results in resistance to activated protein C. Among the patients, the prevalence of the genetic risk factors for thrombosis was not higher than expected on the basis of their prevalence in the general population. Moreover, the prevalence of the factor V Leiden mutation was not increased among the parents of the deceased patients. The individual plasma levels of protein C, protein S, and antithrombin did not differ between the patients with or without severe purpura. The present data constitute circumstantial evidence that primary defects in the natural anticoagulant systems do not play a major role in the severity of the disease course. Screening of patients with infectious purpura for inherited thrombotic risk factors is therefore not indicated.     

Sarcoid-like reaction in the regional lymph nodes and spleen in gastric carcinoma: a clinicopathologic study of five cases

This article summarizes the genetic markers of human venous and arterial thrombotic disorders. For venous thromboembolism, a factor V mutation (Arg 506-->Gln) has the highest risk, followed by protein C, S and antithrombin III gene defects. By contrast, these genetic defects are not associated significantly with arterial atherothrombotic disorders. Instead, a glycoprotein IIIa polymorphism (Pro33 versus Leu 33) has been reported to be associated with myocardial infarction. Fibrinogen Bbeta chain, factor VII, and plasminogen activator inhibitor-1 gene polymorphisms have been reported to influence the plasma levels of these factors and may indirectly be risk factors for arterial thrombotic disorders. Further studies will uncover additional genetic markers for thrombosis.     

Analysis of immunoglobulin genes in splenic marginal zone lymphoma suggests ongoing mutation

BACKGROUND: The incidence of venous thromboembolism has not been well described, and there are no studies of long-term trends in the incidence of venous thromboembolism. OBJECTIVES: To estimate the incidence of deep vein thrombosis and pulmonary embolism and to describe trends in incidence. METHODS: We performed a retrospective review of the complete medical records from a population-based inception cohort of 2218 patients who resided within Olmsted County, Minnesota, and had an incident deep vein thrombosis or pulmonary embolism during the 25-year period from 1966 through 1990. RESULTS: The overall average age- and sex-adjusted annual incidence of venous thromboembolism was 117 per 100000 (deep vein thrombosis, 48 per 100000; pulmonary embolism, 69 per 100000), with higher age-adjusted rates among males than females (130 vs 110 per 100000, respectively). The incidence of venous thromboembolism rose markedly with increasing age for both sexes, with pulmonary embolism accounting for most of the increase. The incidence of pulmonary embolism was approximately 45% lower during the last 15 years of the study for both sexes and all age strata, while the incidence of deep vein thrombosis remained constant for males across all age strata, decreased for females younger than 55 years, and increased for women older than 60 years. CONCLUSIONS: Venous thromboembolism is a major national health problem, especially among the elderly. While the incidence of pulmonary embolism has decreased over time, the incidence of deep vein thrombosis remains unchanged for men and is increasing for older women. These findings emphasize the need for more accurate identification of patients at risk for venous thromboembolism, as well as a safe and effective prophylaxis.     

Homozygous cystathionine beta-synthase deficiency, combined with factor V Leiden or thermolabile methylenetetrahydrofolate reductase in the risk of venous thrombosis

Severe hyperhomocysteinemia in its most frequent form, is caused by a homozygous enzymatic deficiency of cystathionine beta-synthase (CBS). A major complication in CBS deficiency is deep venous thrombosis or pulmonary embolism. A recent report by Mandel et al (N Engl J Med 334:763, 1996) postulated factor V Leiden (FVL) to be an absolute prerequisite for the development of thromboembolism in patients with severe hyperhomocysteinemia. We studied 24 patients with homocystinuria caused by homozygous CBS deficiency from 18 unrelated kindreds for FVL and for the 677C-->T mutation in the methylenetetrahydrofolate reductase (MTHFR) gene and investigated their possible interaction in the risk of venous thrombosis. Thrombotic complications were diagnosed in six patients, of whom only one was a carrier of FVL. On the contrary, thermolabile MTHFR caused by the 677C-->T mutation, was frequently observed among homocystinuria patients, especially among those with thromboembolic complications: three of six homocystinuria patients who had suffered from a thromboembolic event had thermolabile MTHFR. These data indicate that FVL is not an absolute prerequisite and probably not even a major determinant of venous thrombosis in homocystinuria, but, interestingly, thermolabile MTHFR may constitute a significant risk factor for thromboembolic complications in this inborn error of methionine metabolism.