Difference in absolute risk of venous and arterial thrombosis between familial protein S deficiency type I and type III. Results from a family cohort study to assess the clinical impact of a laboratory test-based classification

Hereditary protein S (PS) deficiency type I is an established risk factor for venous thromboembolism. Contradictionary data on type III deficiency suggests a difference in risk between both types. We studied 156 first degree relatives (90% of eligible relatives) from type I deficient probands (cohort 1) and 268 (88%) from type III deficient probands (cohort 2) to determine the absolute risk of venous and arterial thromboembolism. Annual incidences of venous thromboembolism were 1.47 and 0.17 per 100 person-years in deficient and non-deficient relatives in cohort 1 [relative risk (RR) 8.9; 95% confidence interval (CI) 2.6-30.0], and 0.27 vs. 0.24 in cohort 2 (RR 0.9; 95% CI 0.4-2.2). Type III deficiency was demonstrated in 20% of non-deficient relatives in cohort 1 and the annual incidence in this subgroup was 0.70 (RR 4.3;0.95-19.0). The cut-off level of free PS to identify subjects at risk was 30%, the lower limit of its normal range (65%). PS deficiency was not a risk factor for arterial thromboembolism. In conclusion, type I deficiency was found to be a strong risk factor for venous thromboembolism, in contrast with type III deficiency. This was because of lower free PS levels in type I deficient subjects and a free PS cut-off level far below the lower limit of its normal range.

Risk of a first venous thrombotic event in carriers of a familial thrombophilic defect. The European Prospective Cohort on Thrombophilia (EPCOT)

BACKGROUND

Reliable risk estimates for venous thrombosis in families with inherited thrombophilia are scarce but necessary for determining optimal screening and treatment policies.

OBJECTIVES

In the present analysis, we determined the risk of a first venous thrombotic event in carriers of a thrombophilic defect (i.e. antithrombin-, protein C- or protein S deficiency, or factor V Leiden).

PATIENTS AND METHODS

The asymptomatic carriers had been tested prior to this study in nine European thrombosis centers because of a symptomatic carrier in the family, and were followed prospectively for 5.7 years on average between March 1994 and January 2001. Annually, data were recorded on the occurrence of risk situations for venous thrombosis and events (e.g. venous thrombosis, death).

RESULTS

Twenty-six of the 575 asymptomatic carriers (4.5%) and seven of the 1118 controls (0.6%) experienced a first deep venous thrombosis or pulmonary embolism during follow-up. Of these events, 58% occurred spontaneously in the carriers compared with 43% in the controls. The incidence of first events was 0.8% per year (95% CI 0.5-1.2) in the carriers compared with 0.1% per year (95% CI 0.0-0.2) in the controls. The highest incidence was associated with antithrombin deficiency or combined defects, and the lowest incidence with factor V Leiden.

CONCLUSIONS

The incidence of venous events in asymptomatic individuals from thrombophilic families does not exceed the risk of bleeding associated with long-term anticoagulant treatment in the literature (1-3%).

Venenastverschluss und Abduzensparese bei Protein-S-Mangel

BACKGROUND

Protein S deficiency, which exists in 0.7% of the population, is a risk factor for retinal vein branch occlusions and is inherited in an autosomal dominant manner.

METHODS

A genealogical study was carried out on three generations of one family who exhibited different venous occlusions and subsequent complications.

RESULTS

Four members of the family, spanning three generations, suffered from complications of venous thrombosis. In the first generation a great uncle died of complications from a deep leg venous thrombosis. In the second generation, the mother underwent a venous branch thrombosis at the age of 41 with a protein S activity of 18%. Subsequently, a palsy of the N. abducens developed with multiple cerebral lesions (presumably post-thrombotic) in the MRI. Fluorescein angiography showed a typical picture of a venous branch occlusion which had been treated by laser. In the third generation, the 16-year-old daughter developed iliac venous thrombosis and a pulmonary embolism with a protein S activity of 0%. The fluorescein angiography showed distinctively engorged veins. A 28-year-old daughter, with a protein S activity of 16%, remained asymptomatic, although fluorescein angiography demonstrated engorged veins. Protein C activity and APC resistance of all family members were normal. The chromosomal analysis of the family members revealed no morphological aberrations.

CONCLUSION

Protein S deficiency increases the risk of congenital thrombosis in young and middle-aged heterozygous individuals.

[The frequency of venous thromboembolism in women with Leiden mutation in association with pregnancy and puerperium]

OBJECTIVE

The assessment of the frequency of venous thromboembolism (VTE) in women with F V Leiden in association with pregnancy and puerperium and according these results and available data to formulate the principles of thromboprophylaxis.

TYPE OF STUDY

Retrospective case control study.

MATERIALS AND METHODS

The assessment of frequency of VTE in the group of 224 women with F V Leiden in heterozygous form in association with 460 pregnancies and in the group of 40 women with F V Leiden in homozygous form in association with 70 pregnancies. This frequency of VTE in those groups was compared with the frequency of VTE in the control group of 201 women without F V Leiden in association with 422 pregnancies. F V Leiden evaluation was done in the period of 1996-2003.

RESULTS

In the group of women with F V Leiden in heterozygous form VTE occurred 44-fold during pregnancy and puerperium. In 17 cases VTE was manifested in pregnancy (once in Ist trimester, twice in IInd trimester, 14 times in IIIrd trimester), in 27 women VTE occurred in puerperium and always within the first 10 days after delivery. Proximal venous thrombosis was diagnosed in 34 cases, in 5 cases being complicated by pulmonary embolism. In 10 women thrombosis was distal. The frequency of VTE is 9.6%. In the group of women with homozyous form VTE occurred in 14 cases (20%). In 5 cases VTE occurred during pregnancy, in 9 cases after delivery and in all cases within first 2 weeks after delivery. The frequency of VTE in the control group is 0.24%. The results were statistically assessed by Fishers exact test in programme NCSS 2004. Frequency of VTE in both cohorts of women with F V Leiden reached statistical significance in comparison with the control group.

CONCLUSION

Pregnancy and puerperium are significant risk factors for VTE in the group of women with F V Leiden in heterozygous form and mainly in homozygous form.

Superficial Vein Thrombosis and Hypercoagulable States: The Evidence

AIM

To assess the demographic features of superficial vein thrombosis and its relation with the occurrence of hypercoagulable states.

METHODS

Data were gathered from pertinent papers using a MEDLINE search and an exhaustive bibliography review. Studies were considered only when they contained material to superficial vein thrombosis and hypercoagulable states.

RESULTS

The difference among the patients and the methods used made the comparison difficult and did not allow a pool analysis of the data. Superficial vein thrombosis is a common condition, and its prevalence is underestimated. Several risk factors are associated with superficial vein thrombosis, and a strong relation was seen with certain thrombophilias.

CONCLUSIONS

Although superficial vein thrombosis most often is perceived as benign, it can coexist with hypercoagulable states. In patients with spontaneous onset of superficial vein thrombosis, there should be a lower threshold in testing for hypercoagulable states.

Familial homocystinuria

Two cases of siblings diagnosed as cases of familial homocystinuria are reported. Both the cases have classical presentation of familial homocystinuria including history of dislocation of lens of the right eye. Brother had history of psychomotor retardation while sister had a significant history of deep vein thrombosis. Levels of plasma homocysteine were elevated and urinary homocysteine was positive in both the cases.

Prothrombin 20210A mutation: a mild risk factor for venous thromboembolism but not for arterial thrombotic disease and pregnancy-related complications in a family study

BACKGROUND

The prothrombin 20210A mutation has been associated with an increased risk of venous thromboembolism (VTE). Its relationship with arterial disease and pregnancy-related complications is, however, still uncertain. The aim of this study was to estimate the incidences of first venous and arterial thrombotic events and pregnancy-related complications in relatives of patients with the mutation.

METHODS

After clinical classification, the presence of the mutation was determined in first-degree relatives of consecutive patients with the mutation and a history of VTE or premature atherosclerosis. Relatives with and without the mutation were compared.

RESULTS

Of all relatives, 204 (50%) were heterozygous, 5 were homozygous, and 198 had a normal genotype. The annual incidence of a first episode of VTE was 0.35% and 0.18% in carriers and noncarriers, respectively (odds ratio [OR], 1.9; 95% confidence interval [CI], 0.9-4.1); the annual incidence of a first arterial thrombosis was 0.22% and 0.15% in carriers and noncarriers, respectively (OR, 2.3; 95% CI, 0.8-6.3). The annual incidence of a first myocardial infarction was 0.14% (95% CI, 0.05%-0.23%) and 0.05% (0.01%-0.14%) in carriers and noncarriers, respectively (OR, 4.7; 95% CI, 1.0-22.5; P =.06). In particular, homozygous carriers were at increased risk of VTE (OR, 6.0; 95% CI, 1.3-27.2), whereas a history of VTE in the proband influenced the risk of VTE in the relatives. Women with the mutation did not experience significantly more pregnancy-related complications than their relatives with a normal genotype.

CONCLUSIONS

The prothrombin mutation is a mild risk factor for VTE within families of carriers but does not seem to play an important role in arterial thrombotic disease, with the exception of myocardial infarction, or in pregnancy-related complications.

Marburg I polymorphism of factor VII–activating protease is associated with idiopathic venous thromboembolism

The factor VII–activating protease (FSAP) variant Marburg I is known to attenuate the profibrinolytic system in vitro and was recently shown to be a significant predictor for the evolution and progression of carotid stenosis. The objective of this case-control study was to assess FSAP Marburg I's role in the occurrence of venous thromboembolism (VTE). The frequency of FSAP Marburg I was significantly increased in patients with a history of VTE (17 of 213 patients, 8.0%, P = .014) or idiopathic VTE (12 of 103 patients, 11.7%, P = .002) compared to healthy controls (5 of 213 controls, 2.3%). Logistic regression analysis confirmed FSAP Marburg I to be an independent risk factor for VTE (odds ratio, 3.5; 95% confidence interval [CI], 1.2-10.0) and idiopathic VTE (odds ratio, 6.2; 95% CI, 2.0-18.9).

The incidence of venous thromboembolism among Factor V Leiden carriers: a community-based cohort study

While Factor V (FV) Leiden is a risk factor for venous thromboembolism (VTE), the incidence of VTE among FV Leiden carriers is uncertain. The objective of the study was to estimate the overall age-specific and pregnancy-related VTE incidence and the relative risk among FV Leiden carriers. In a community-based sample of 3424 south-eastern Minnesota residents, 230 (6.7%) were genotyped as FV Leiden carriers; 220 carriers (mean age = 68 years) could be matched to a non-carrier on age, gender, ethnicity and length of medical history. We performed a retrospective cohort study of carriers and non-carriers by reviewing the complete medical records in the community for demographic and baseline characteristics, pregnancies and live births, and first lifetime VTE. Over 14 722 person-years, 24 (10.9%) carriers developed VTE [overall incidence = 163 (95% CI 104, 242) per 100,000 person-years]. VTE incidence rates for ages 15-29, 30-44, 45-59 and > or = 60 years were 0, 61, 244 and 764 per 100,000 person-years, respectively (cumulative VTE incidence at age 65 years = 6.3%). VTE incidence for carriers did not differ significantly from that for non-carriers except for those > or = 60 years old (relative risk = 3.6; 95% CI 2.0, 6.0). There were 311 live births among 130 women carriers; no VTE events occurred during pregnancy or postpartum [incidence = 0 (95% CI 0, 1186) per 100,000 women-years]. Most FV Leiden carriers do not develop VTE. Among all carriers, those > or = 60 years old are at the highest risk for VTE. The incidence of VTE among asymptomatic women carriers during pregnancy is low and insufficient to warrant prophylaxis.

Homocysteine, MTHFR and risk of venous thrombosis: a meta-analysis of published epidemiological studies

CONTEXT

It has been suggested that elevated total plasma homocysteine levels are associated with the risk of venous thrombosis.

OBJECTIVE

To assess the relationship of homocysteine and the MTHFR 677TT genotype and the risk of venous thrombosis by conducting a meta-analysis of all relevant studies.

DATA SOURCES AND SELECTION

Studies (case-control or nested case-control) were identified by searches of electronic literature for relevant reports published before July 2003 on homocysteine and the MTHFR 677TT genotype and venous thrombosis as an end-point, by hand-searching reference lists of original articles (including meta-analyses) on this topic and by contact with investigators in the field.

DATA EXTRACTION

A meta-analysis of 24 retrospective (n = 3289 cases) and three prospective studies (n = 476 cases) was carried out to examine the association of homocysteine with venous thrombosis. A meta-analysis of 53 studies (n = 8364 cases) of the MTHFR 677TT genotype (that increases homocysteine) was carried out to assess if this association is causal.

DATA SYNTHESIS

A 5 micromol L(-1) higher measured homocysteine level was associated with a 27% (95% CI: 1-59) higher risk of venous thrombosis in prospective studies and a 60% (95% CI: 10-134) higher risk in retrospective studies. The 677TT genotype was associated with a 20% (95% CI: 8-32) higher risk of venous thrombosis compared with the 677CC genotype. In contrast with non-American studies, the 677TT genotype had no effect on venous thrombosis in North America, due probably to the higher intake of folate and riboflavin in North America.

CONCLUSION

This meta-analysis of prospective and retrospective studies demonstrates a modest association of homocysteine with venous thrombosis. The elevated risk associated with the MTHFR 677TT genotype provides some support for causality.

High factor VIII levels in venous thromboembolism show linkage to imprinted loci on chromosomes 5 and 11

High factor VIII (FVIII) levels are known to be a risk factor for deep venous thrombosis, but the mechanisms responsible for high FVIII levels remain unclear. Here, a new phenotype “FVIII level residuum” (FVIII-R) was defined in order to eliminate the impact of common determinants on FVIII levels. We studied 13 families of patients with thrombosis and reproducibly high FVIII levels of unknown origin. Since familial clustering was evident, we looked for a possible genetic basis. A genome scan was performed with 402 evenly spaced microsatellite markers. A quantitative linkage analysis using variance component methods showed suggestive evidence for linkage of FVIII-R with a locus on chromosome 8 (logarithm of odds [LOD] = 2.1). In addition, we performed parametric exploratory linkage analysis of dichotomized FVIII-R, taking a parent-of-origin effect into account. Single-trait-locus MOD-score analysis showed suggestive evidence for linkage under an imprinting model at chromosomes 5 and 11. Furthermore, a 2-trait-locus analysis under a multiplicative model for the loci of chromosomes 5 and 11 yielded a remarkable LOD of 4.44. It confirmed the finding of paternal imprinting, obtained by single-trait-locus analysis, at both loci. Our results suggest that high FVIII levels in venous thromboembolism represent a complex trait caused by several genetic factors.

Prothrombin 20210A and Oral Contraceptive Use as Risk Factors for Cerebral Venous Thrombosis

BACKGROUND

This study investigates the association between cerebral vein thrombosis (CVT) and the mutations FV 1691A (factor V Leiden), PT 20210A and MTHFR 677TT and acquired factors including oral contraceptive (OC) use.

METHODS

26 patients (21 females) and 217 healthy controls (134 females) were studied. Multiple regression analysis was performed.

RESULTS

The frequency of the three mutations in cases and controls were: PT 20210A, 23 versus 1%, odds ratio (OR) 21.40 (95% CI 4.29-118.75), p < 0.001; FV 1691A, 8 versus 1%, OR 5.94 (95% CI 0.66-46.9); MTHFR 677TT, 4 versus 7%, OR 0.54 (95% CI 0.03-4.08). OC use was more frequent in female patients over 14 years old than in controls (84 vs. 40%, OR 8.15, 95% CI 2.09-37.13, p < 0.001). The model that best explained the thrombotic risk included PT 20210A and OC use.

CONCLUSIONS

PT 20210A and OC use are the main thrombophilic risk factors predisposing to CVT and should be routinely investigated in patients with this disease.

Tests of trait—haplotype association when linkage phase is ambiguous, appropriate for matched case-control and cohort studies with competing risks

The impact of competing risks on tests of association between disease and haplotypes has been largely ignored. We consider situations in which linkage phase is ambiguous and show that tests for disease-haplotype association can lead to rejection of the null hypothesis, even when true, with more than the nominal 5 per cent frequency. This problem tends to occur if a haplotype is associated with overall mortality, even if the haplotype is not associated with disease risk. A small simulation study illustrates the magnitude of bias (high type I error rate) in the context of a cohort study in which a modest number of disease cases (about 350) occur over time. The bias remains even if the score test is based on a logistic model that includes age as a covariate. For cohort studies, we propose a new test based on a modification of the proportional hazards model and for case-control studies, a test based on a conditional likelihood that have the correct size under the null even in the presence of competing risks, and that can be used when haplotype is ambiguous.

Venous thrombosis: the role of genes, environment, and behavior

Over the last decade we have witnessed an avalanche of newly identified risk factors for venous thrombosis. This has advanced our knowledge of its etiology, because more determinants have been described and because the underlying concepts have received a new and broader understanding. Venous thrombosis is a common multicausal disease occurring as the result of interacting genetic, environmental and behavioral risk factors. Some of these have been known since medieval times, such as the increased risk of thrombosis during immobilization in pregnancy and after childbirth (although retained milk of the breast-feeding mother was seen as the primary cause for the latter). Pregnancy and puerperium still cause thrombosis, as do exogenous hormones in oral contraceptives and hormonal replacement therapy. Furthermore, the immobilization in the puerperium of the old days translates directly to situations of immobilization in current times, such as prolonged travel in airplanes or excessive electronic gaming. While pedigrees with abundant thrombosis were observed in the early 1900s, the first cause of heritable thrombophilia (antithrombin deficiency) was discovered in 1965, with the subsequent identification of deficiencies of protein C and protein S in the early 1980s. These were uncommon and strong risk factors, whereas the more recently discovered genetic variants are common and weak, and cause disease only in the presence of other factors.

Inherited risk factors for venous thrombosis

Venous thrombosis occurs as a consequence of genetic and environmental risk factors. Since the discovery of factor V Leiden, the most common genetic risk factor, there has been intense interest in clarifying the roles of genes and the environment with thrombosis risk. The translation of this risk information to clinical practice is a challenging one in the setting of a rapidly expanding knowledge base that includes application of genetic medicine. There are benefits, but also potential harms, of testing for inherited disorders associated with thrombosis. This paper reviews inherited risk factors for thrombosis and discuss clinical applications of testing.

[Study on the significance and application of crossover analysis in assessing gene-environmental interaction]

OBJECTIVE

To examine the significance of crossover analysis in gene-environmental interaction studies.

METHODS

Through elaboration of a case-control study on the increased risk of venous thrombosis in oral-conceptive users who were carriers of factor V Leiden mutation, core information from 2 x 4 crossover table were analyzed and compared with stratified analysis and 'case only' study.

RESULTS

Different models (additive or multiplicative) in analyzing gene-environmental interaction yielded different results. The result of interaction based on multiplicative model was 1.35 (P > 0.05), compatible with that of stratified analysis and case only study. Calculated by crossover analysis based on additive model, synergy index S(S), attributable proportion of interaction (AP) and relative excess risk of interaction (RERI) appeared to be 3.90, 72.24%, 25.08 (P > 0.05) respectively.

CONCLUSION

Crossover analysis should further be applied in gene-environmental interaction studies.

Factor V Leiden, FII G20210A, MTHFR C677T mutations as risk factors for venous thrombosis during pregnancy and puerperium

Background. Venous thrombosis is the most common cause of obstetric morbidity and mortality during pregnancy and puerperium. The incidence of pregnancy associated venous thrombosis varies from 1 in 1000 to 1 in 2000 deliveries. Factor V G1691A (FV Leiden), FII G20210A and MTHFR C677T mutations are the most common genetic risk factors for thromboembolism. The aim of this study was to establish the presence of these risk factors in a group of women with an episode of deep venous thrombosis during pregnancy or puerperium. Methods. The study was carried in a group of 45 women with the first episode of deep venous thrombosis during pregnancy or puerperium. The patients with antiphospholipid antibodies, antithrombin III, protein C or protein S deficiency, and autoimmune and malignant diseases were excluded from the study. FV Leiden, FII G20210A, and MTHFR C677T mutations were detected by polymerase chain reaction, followed by digestion with specific restriction enzymes. Results. Twenty heterozygous carriers of the FV Leiden mutation and one homozygous carrier were detected, which represents the frequencies of 44.4% and 2.2%, respectively. For the FII G20210A mutation, six heterozygous carriers were identified, giving the frequency of 13.3%. The MTHFR C677T mutation was observed in 31 patients (22 heterozygous and 9 homozygous carriers) which represents the frequencies of 48.9% and 20%, respectively. Conclusion. Our study suggested that the obligatory testing for FV Leiden and FII G20210A mutations was strongly recommended in women with history of venous thrombosis during pregnancy and puerperium. We found a slight effect of MTHFR 677T allele, but it should be considered in association with other risk factors.

Relationship between ABO and Secretor genotype with plasma levels of factor VIII and von Willebrand factor in thrombosis patients and control individuals

In contrast to earlier reports, this study examined the relationship between plasma levels of factor VIII (FVIII) and von Willebrand factor (VWF) and ABO blood group and secretor status at the genetic level in 355 patients with venous thrombosis as well as in 236 controls. ABO glycosyl transferase alleles A(1) and B were more frequent in the thrombosis collective and alleles O(1), O(2) and A(2) were more frequent in the controls. A low-risk group for venous thrombosis of individuals with genotypes O(1)O(1), O(1)O(2) and O(1)A(2) (H-antigen rich) could be distinguished from a high-risk group with genotypes A(1)A(1), A(1)B, O(1)A(1) and O(1)B (H-antigen poor). In both the thrombosis and control groups, the H-antigen rich group showed significantly lower levels of FVIII coagulant activity (FVIII:C) and VWF antigen (VWF:Ag) than the H-antigen poor group. The frequency of the different secretor genotypes in the thrombosis group was not different from that in the control group. No significant differences of FVIII:C and VWF:Ag levels were seen between SeSe, Sese and sese individuals in the thrombosis and in the control group. Thus the risk of venous thrombosis is associated with the ABO blood group genotype but not with secretor status.

A naturally occurring E30Q mutation in the Gla domain of protein Z causes its impaired secretion and subsequent deficiency

Protein Z is a vitamin K-dependent glycoprotein that plays a role in the regulation of coagulation. A nucleotide substitution of G by C in exon II of the protein Z gene, resulting in the replacement of Glu-30 with Gln (E30Q), and a G to A transition at the 79th nucleotide in intron F (IntF79G/A) were heterozygously identified in a patient with a severe thrombotic tendency, whose plasma protein Z level was about 15% of normal. Other vitamin K-dependent coagulation factors were within normal ranges. Glu-30 is one of 13 gamma-carboxylation sites in protein Z and is well conserved among vitamin K-dependent proteins. Expression studies revealed that the E30Q mutant was not released from synthesizing cells, although wild-type protein Z was readily secreted in a vitamin K-dependent fashion. The E30Q mutant was N-glycosylated, gamma-carboxylated, and translocated from the endoplasmic reticulum (ER) to the Golgi in the presence of vitamin K, as was the wild type. Coexpression of E30Q with wild-type protein Z interfered with the secretion of the wild type, while only a minor or no effect was observed on the secretion of factor X and plasminogen. The IntF79A allele has been reported to be also associated with lowered protein Z levels.