COVID-19 susceptibility variants associate with blood clots, thrombophlebitis and circulatory diseases

Epidemiological studies suggest that individuals with comorbid conditions including diabetes, chronic lung, inflammatory and vascular disease, are at higher risk of adverse COVID-19 outcomes. Genome-wide association studies have identified several loci associated with increased susceptibility and severity for COVID-19. However, it is not clear whether these associations are genetically determined or not. We used a Phenome-Wide Association (PheWAS) approach to investigate the role of genetically determined COVID-19 susceptibility on disease related outcomes. PheWAS analyses were performed in order to identify traits and diseases related to COVID-19 susceptibility and severity, evaluated through a predictive COVID-19 risk score. We utilised phenotypic data in up to 400,000 individuals from the UK Biobank, including Hospital Episode Statistics and General Practice data. We identified a spectrum of associations between both genetically determined COVID-19 susceptibility and severity with a number of traits. COVID-19 risk was associated with increased risk for phlebitis and thrombophlebitis (OR = 1.11, p = 5.36e-08). We also identified significant signals between COVID-19 susceptibility with blood clots in the leg (OR = 1.1, p = 1.66e-16) and with increased risk for blood clots in the lung (OR = 1.12, p = 1.45 e-10). Our study identifies significant association of genetically determined COVID-19 with increased blood clot events in leg and lungs. The reported associations between both COVID-19 susceptibility and severity and other diseases adds to the identification and stratification of individuals at increased risk, adverse outcomes and long-term effects.

Familial antithrombin III deficiency as pathogenesis of deep venous thrombosis

A family including 18 members with decreased antithrombin III (AT III), measured with both a biological and an immunochemical method, is described. The pattern found on crossed immunoelectrophoresis, using heparin in the agarose in the first run, was normal, though the peaks were low. This suggests decreased synthesis of a normal protein in the affected members. AT III deficiency occurred in both the paternal and the maternal branch, of the above 18 persons had had at least one thromboembolic episode. Some of the episodes had been precipitated by the presence or occurrence of some predisposing event or circumstance. This suggests the possible occurrence of a gene making some of the maternal family members more susceptible to certain trigger factors, such as surgery, infection, pregnancy, and the puerperium. The mode of inheritance filled all the criteria for autosomal dominant transmission. Prophylactic treatment, preferably oral anticoagulants and/or dextran, is recommended for all persons with a low AT III concentration in any situation known to increase the predisposition to thrombosis. The effect of heparin in these patients is impaired since the heparin co-factor, which is identical with AT III, is lowered.

A family with thromboembolic disease associated with deficient fibrinolytic activity in vessel wall

Defective fibrinolytic activity is often a contributory factor in deep venous thrombosis. A family with a high incidence of venous thrombosis in association with such a defect is presented. Of 13 family members who had had thrombosis, 12 showed a defective capacity to release fibrinolytic activity from vessel wall after venous occlusion and/or infusion of DDAVP, a vasopressin derivative. The fibrinolytic activator activity of the vessel wall was normal in all cases. This seems to be the first family in which there is evidence of an inherited abnormal fibrinolytic activity.

Integrating genomic based information into clinical warfarin (Coumadin) management: an illustrative case report

Warfarin is a well established oral anticoagulant for the treatment of thromboembolic disorders. Warfarin therapy is complicated by a narrow therapeutic index and marked inter-individual dose variability with therapeutic doses ranging from 1 mg to 10 mg/day. Recently genetic variation and resultant drug metabolizing polymorphisms have been found to contribute to warfarin dose variability with resultant hemorrhagic or thromboembolic complications. Cytochrome P4502C9 alters the rate of warfarin metabolism and clearance. A second enzyme, Vitamin K Epoxide Reductase Complex (VKORC) binds and reduces Vitamin K which is necessary for activation of clotting Factors II, VII, IX and X. The VKORC1 gene encodes for Vitamin K Epoxide Reductase Complex subunit 1, a key component of VKORC. The combination of physiologic factors (30%), CYP2C9 variations (20%) and VKORC1 variants (25%) accounts for approximately 75% of warfarin dose variability. This illustrative case report demonstrates the clinical importance of this new information. Clinicians need to incorporate these new genomic findings into appropriate management of warfarin dose anticoagulation.

A case of hereditary protein S deficiency presenting with cerebral sinus venous thrombosis and deep vein thrombosis at high altitude

A 35-year-old healthy male with no history of any past medical illness developed severe headache, vomiting and drowsiness while at high altitude (4,572 m) in the eastern Himalayan ranges. He was evacuated to a tertiary-care hospital where he was diagnosed to have cerebral sinus venous thrombosis (CSVT) on magnetic resonance imaging, with deep vein thrombosis (DVT) of his right popliteo-femoral vein on color Doppler study. Investigation for thrombophilia revealed protein S (PS) deficiency in this patient. Family screening revealed low levels of PS in two elder brothers. One brother had a history of 'stroke in young' at the age of 20 years with the other being asymptomatic. This established the hereditary nature of PS deficiency. We are not aware of any previously published report on hereditary PS deficiency combined with CSVT and DVT occurring at high altitude. However, 1 case of protein C deficiency with CSVT has been reported previously.

Lemierre's syndrome and genetic polymorphisms: a case report

Background

Lemierre's syndrome presents a classic clinical picture, the pathophysiology of which remains obscure. Attempts have been made to trace genetic predispositions that modify the host detection of pathogen or the resultant systemic reaction.

Case presentation

A 17-year old female, with no previous medical history, was admitted to the intensive care unit for septic shock, acute respiratory distress syndrome and Lemierre's syndrome. Her DNA was assayed for single nucleotide polymorphisms previously incriminated in the detection of the pathogen, the inflammatory response and the coagulation cascade. We observed functional variations in her Toll like 5 receptor (TLR 5) gene and two coagulation variations (Tissue Factor (TF) 603 and Plasminogen-Activator-Inhibitor-1 (PAI-1) 4G-4G homozygosity) associated with thrombotic events.

Conclusion

The innate immune response and the prothrombogenic mutations could explain, at least in part, the symptoms of Lemierre's syndrome. Genomic study of several patients with Lemierre's syndrome may reveal its pathophysiology.

[Erythema of the leg]

Wir berichten von einem 62-jährigen Patienten mit bekannten postthrombotischen Veränderungen im Bereich der V. poplitea links und passageren atemabhängigen Thoraxschmerzen in der Anamnese, welcher sich aktuell mit einer Thrombophlebitis der gesamten V. saphena magna rechts präsentiert. Differentialdiagnosen zur Thrombophlebitis umfassen im Wesentlichen eine TVT, eine Zellulitis/Pannikulitis, eine Lymphangitis, Insektenstiche, das Erythema nodosum, die kutane Polyarteriitis nodosa (PAN), das sarkoide Granulom und das Kaposi-Sarkom. Aufgrund des spontanen Auftretens der Thrombophlebitis und der indirekten Hinweise für thromboembolische Ereignisse in der Anamnese haben wir eine gerinnungsphysiologische Abklärung durchgeführt, welche eine homozygote Faktor V Leiden-Mutation als wahrscheinliche Ursache ergab. Da wir von einer symptomatischen Gerinnungsstörung ausgehen, haben wir dem Patienten bei einem 50- bis 100-fach erhöhten Thromboserisiko die lebenslange Antikoagulation empfohlen. Falls eine bezüglich thromboembolischen Ereignissen blande Anamnese vorgelegen hätte, hätten wir dem Patienten lediglich zu einer prophylaktischen Verwendung von niedermolekularen Heparinen in Risikosituationen geraten, da in diesem Fall bedeutende protektive Faktoren postuliert werden müssen.

Does use of hormonal contraceptives among women with thrombogenic mutations increase their risk of venous thromboembolism? A systematic review

Because use of combined oral contraceptives (COCs) confers some risk of venous thromboembolism (VTE), there is concern that this effect may be greater among women with thrombogenic mutations. We searched the MEDLINE and EMBASE databases for all articles published from January 1966 through September 2004 for evidence relevant to hormonal contraception and thrombogenic mutations. Of 301 articles identified by the search strategy, 16 evaluated COCs, and no studies were found for other hormonal methods. We used standard abstract forms and grading systems to summarize and assess the quality of the evidence. A total of 10 studies together provided "good" evidence of a greater risk of VTE (risk ratios of 1.3-25.1) and cerebral vein or cerebral sinus thrombosis among COC users with factor V Leiden mutation when compared with nonusers who have the mutation. The evidence for prothrombin and other thrombogenic mutations was not as strong as for factor V Leiden mutation. It is unclear whether the type of COC or duration of use modifies the risk of VTE among women with thrombogenic mutations.

Paradoxical coronary embolism causing non-ST segment elevation myocardial infarction in a case of pulmonary embolism

We describe the case of a 61-year-old woman who simultaneously suffered a pulmonary embolism and a myocardial infarction due to paradoxical coronary artery embolism. Transesophageal echocardiography with injection of agitated hydroxyethyl starch revealed a patent foramen ovale. Thrombophlebistis of the left saphenous vein with extension of thrombus into the femoral vein could be identified as the source of embolism. Paradoxical coronary embolism is an underrecognized cause of MI. Diagnosis is particularly difficult, when MI and PE coincide, because of the similarity in clinical signs and symptoms of both entities. A high level of clinical suspicion and echocardiography, especially if performed soon after presentation, can be the clue to early diagnosis of PDE.

Association of class I HLA antigens with the clinical manifestations of Turkish patients with Behçet's disease

Genetic factors appear to be important in the pathogenesis of Behçet's disease. Although it is known to be strongly associated with HLA-B 51, the association of HLA class I antigens with specific clinical findings of the disease has not been studied extensively and the few studies are conflicting. The aim of this study was to investigate the association of HLA class I alleles with the manifestations of Behçet's disease in Turkish patients. Eighty-five patients with Behçet's disease were typed for HLA-A, B, and C antigens with the serologic, standard microlymphocytotoxicity technique. Possible associations of the HLA complex with clinical findings of Behçet's disease were examined. Statistically significant findings are as follows (P < 0.05): increased HLA-B 51 and decreased HLA-B35 frequency in patients with thrombophlebitis, increased HLA-A29 and decreased HLA-Bw6 frequency in patients with ocular involvement, decreased HLA-Cw2 frequency in patients with erythema nodosum, and decreased HLA-Cw 7 frequency in patients with genital ulceration. Of particular note, the results of this study suggest that the presence of HLA-B 51 and the absence of HLA-B35 can be regarded as laboratory risk factors of venous thrombosis in patients with Behçet's disease.

[Genetic risk factors of thrombosis]

Genetic risk factors became a frequent predisposing cause of venous thromboembolism (VTE) since the discovery of two mutations: factor V Leiden and G20210A mutation of prothrombin gene. One of these both mutations is associated with around 25% of VTE events. Interaction of genetic risk factors, such as interaction of FV Leiden or G20210A mutation of prothrombin with antithrombin, protein C or protein S deficiencies, as well as interaction with acquired risk factors, have demonstrated that venous thrombosis is a multifactorial disease. The search for thrombophilia must be done in VTE occurring before the age of 45, in case of recurrencies and in case of familial history of VTE.

Low level of circulating activated protein C is a risk factor for venous thromboembolism

The levels of circulating activated protein C (APC) reflect in vivo protein C activation. The aim of this study was to determine whether a low APC level is an independent risk factor for venous thromboembolism (VTE). We measured APC in 160 patients with a history of VTE and without recognized thrombophilic defects, and in 199 healthy individuals. The mean (+/- SD) APC level was lower in patients (0.99 +/- 0.44 ng/ml) than in controls (1.19 +/- 0.41 ng/ml) (p < 0.0001), and showed a different distribution in the two groups. Thirty-eight patients (23.7%) had APC levels below the 5th percentile of the control group (<0.69 ng/ml) and 57 patients (35.6%) had APC levels below the 10th percentile (<0.77 ng/ml). APC levels <0.69 ng/ml increased the risk of a single or recurrent episode of VTE 4.2-fold (95% confidence interval, 2.0-9.0) or 6.9-fold (2.6-17.9). respectively, and APC levels <0.77 ng/ml increased these risks 3.4-fold (1.9-6.2) or 5.1-fold (2.3-11.2), respectively, compared with controls. Familial studies revealed that in some cases the low APC phenotype seems to be hereditary. We conclude that a low level of circulating APC in individuals without any of the most recognized thrombophilic defects is a prevalent, independent risk factor for VTE, and that it predisposes to recurrent VTE.

Prevalence of a 23bp insertion in exon 3 of the endothelial cell protein C receptor gene in venous thrombophilia

BACKGROUND

The endothelial cell protein C receptor (EPCR) enhances protein C activation by the thrombin-thrombomodulin complex. As evidence is accumulating that EPCR is an important component of the protein C anticoagulant pathway, polymorphisms in the EPCR gene might be candidate risk factors predisposing to venous thromboembolism (VTE). Recently, a 23bp insertion in exon 3 of the EPCR gene has been identified, which duplicates the preceding 23 bases and results in a STOP codon downstream from the insertion point. However, the clinical significance of this mutation in VTE remains to be clarified.

METHODS AND RESULTS

In this study we evaluated the EPCR 23bp insertion in 889 patients with documented VTE and in 500 healthy controls. The prevalence of the EPCR insertion among patients was 0.1%, which was not significantly different compared to controls (0.6%, p = 0.1).

CONCLUSIONS

Our findings showed that the EPCR 23bp insertion is very rare in both patients with VTE and the general population and failed to support an association between the EPCR 23bp insertion and an increased risk of VTE.

Deep vein thrombosis during enoxaparin prophylactic treatment in a young pregnant woman homozygous for factor V Leiden and heterozygous for the G127-->a mutation in the thrombomodulin gene

Variability of thrombotic disease among individuals homozygous for factor V Leiden has been described. It has been shown that some thrombotic patients carry an additional genetic risk factor such as protein C, protein S, antithrombin deficiency or the G20210A mutation on the prothrombin gene. The occurrence of a deep vein thrombosis during enoxaparin prophylactic treatment in a pregnant woman homozygous for factor V Leiden, without other known prothrombotic genetic factors, led us to investigate her thrombomodulin gene. We found that the patient was heterozygous for the previously described G127-->A mutation, which results in an Ala25-->Thr substitution. Furthermore, for this patient, the allelic combination at the 1418 polymorphic site was C/T, which predicts an Ala455-->Val replacement. Although larger studies are required, this case report suggests that thrombomodulin gene mutations could be an additional genetic risk factor for thrombosis in carriers of the factor V Leiden mutation.

Prevalence of factor V Leiden mutation in various populations

Resistance to activated protein C (APC) is the most common inherited risk factor for venous thrombosis. Most cases of APC resistance are caused by the point mutation nt 1691 G-A in factor V gene, referred to as factor V Leiden mutation. As initially shown in a Dutch population, this mutation has a carrier rate of 2.9%, the most frequent genetic disposition for thrombophilia and deep venous thrombosis. By large-scale epidemiological studies we have determined the prevalence of factor V Leiden mutation in populations from Poland (200), Argentina (215), Venezuela (126), Costa Rica (196), and India (150). The prevalences have been estimated for Poland (Warsaw) 5.0%, Argentina (Buenos Aires) 5.1%, Venezuela (Valencia) 1.6%, Costa Rica (San José) 2.0%, and India (Punjab) 1.3%. Based on worldwide distribution, it can be hypothesized that the factor V Leiden mutation has originated and accumulated in central European Caucasians and spread over the world by migration.

Common C677T polymorphism in the methylenetetrahydrofolate reductase gene increases the risk for deep vein thrombosis in patients with predisposition of thrombophilia

The alanine/valine (A/V) gene polymorphism of 5, 10-methylenetetrahydrofolate reductase (MTHFR), one of the key enzymes catalyzing remethylation of homocysteine, has been reported and the VV genotype is associated with increased plasma homocysteine levels as a result of the reduced activity and increased thermolability of this enzyme. Although previous studies have suggested that the VV genotype is a risk factor for arterial occlusive disease, whether the VV genotype is a risk factor for venous thrombosis is still controversial. Here we screened 72 Japanese patients with deep venous thrombosis (DVT) and 85 controls for this mutation, and we measured plasma levels of homocysteine to determine whether the thermolabile variant with the VV genotype is a risk factor for DVT in a Japanese population. Of the 72 patients with DVT, 10 (13.9%) were found to be homozygous for the VV genotype, and in 6 (7.0%) of 85, control individuals and the difference was not significant (odds ratio=2.12, 95% CI=0.73-6.16, p=0.19). When we divided the DVT patients into subgroups, with and without predisposition of thrombophilia, including deficiencies of proteins C and S, plasminogen, and lupus anticoagulant, the prevalence of the VV genotype in DVT patients with predisposition was significantly higher than that of the normal controls (odds ratio=5.99, 95% CI=1. 56-22.96, p=0.01). However, the prevalence of the VV genotype in DVT patients without predisposition was not significantly different from that of the normal controls (odds ratio=1.20, 95% CI=0.32-4.47, p=0. 75). The plasma homocysteine levels in patients with DVT (11.6+/-5.2 nmol/ml) was not significantly different from that of the control subjects (11.6+/-3.7 nmol/ml). Individuals with the VV genotype showed higher plasma homocysteine levels (15.4+/-6.9 nmol/ml) than did individuals with the AV genotype (11.2+/-3.7 nmol/ml, p=0.009) or in individuals with the AA genotype (11.1+/-4.2 nmol/ml, p=0.004). Serum folate and vitamin B12 levels were not correlated with the plasma homocysteine levels. In conclusion, even though homozygosity for the VV genotype of the MTHFR gene was associated with higher plasma homocysteine levels, we found no association between plasma levels of homocysteine and DVT or between the genotype of the MTHFR gene and the DVT incidence. However, we found that the VV genotype of the MTHFR gene is a risk factor for DVT only when combined with the predisposition of thrombophilia.

Deep vein thrombosis during administration of HMG for ovarian stimulation

We report a case of activated protein C (APC) resistance and deep calf vein thrombosis under controlled ovarian stimulation for in vitro fertilization. The thrombosis occurred before administration of human chorionic gonadotrophin for ovulation induction on the 8th day of hMG (human menopausal gonadotrophin). The patient was stimulated according to the long luteal protocol. Cases of arterial and venous thrombosis as a result of ovarian stimulations are reviewed.

[Lowering high levels of fasting total homocysteine with folic acid and vitamins B in patients with venous thromboembolism: relationship between response and the C677T methylenetetrahydrofolate reductase (MTHRF) genotype]

BACKGROUND

High levels of plasma total homocysteine (tHcy) are involved in arterial or venous occlusive diseases. It essentially depends on the nutritional status of folic acid (FA) and vitamins B12 or B6, but also on the methylenetetrahydrofolate reductase (MTHFR) enzymatic activity. We aim to evaluate the response of the hyperhomocysteinemia (HHcy) to a standard schedule of vitamin supplementation, according with the MTHFR genotype.

PATIENTS AND METHODS

227 patients, diagnosed with venous thromboembolism (VTE) were analysed for tHcy (in fasting conditions), and for the MTHFR-C677T gene polymorphism. When the tHcy exceeded the cut-off point (men = 16, women = 15 mumol/l), the patients were supplemented with a dose equivalent to 1 mg FA, 0.2 mg B12 and 100 mg of B6, daily by 6 weeks. Afterwards they were reanalysed and the reduction was stratified by MTHFR genotype, looking for any difference in the response.

RESULTS

The mean fasting tHcy was 12.3 mumol/l (SD = 8). The 51 hyperhomocysteinemic patients (22%) were older (65.1 y) than the normal ones (55.0 y) (p = 0.0001). The treatment was carried out properly in 46 patients (90%). The pre-treatment mean Hcy was 23.2 (SD = 10.5) mumol/l, and it was reduced to 13.0 (SD = 5.9) (p = 0.0001) (mean reduction = 42.1%). By genotype, the C/C reduced from 21.0 to 13.2 mumol/l (37%) (n = 18), the C/T from 25.0 to 12.6 mumol/l (46%) (n = 24), and the abnormal homozygotes T/T from 22.7 to 14.5 mumol/l (39%) (n = 4), although no statistical significant differences were found. In 80% of cases (37/46), tHcy values normalised. A negative correlation (r = -0.471) (p = 0.005) was observed between age and response.

CONCLUSIONS

The FA/B6/B12 based therapy reduces in a simple, quick and effective way (> 40% in 6 weeks) the pathologic tHcy levels on a VTE population and this is not influenced by the MTHFR genotype. As HHcy seems related with recurrences of venous thrombosis, we could speculate if it would be useful to analyse routinely the tHcy, attempting reduction in selected cases.

[Multiple phlebothrombosis following cesarean section due to heterozygous factor V Leiden mutation detected post partum]

Activated protein C resistance in factor V Leiden mutation is currently the most frequent hereditary defect accompanied by high risk of thromboembolism. Thromboembolism often develops in the presence of additional risk factors such as pregnancy, birth, taking oral contraceptives, immobilization and surgical operations. A case of multiple phlebothrombosis following caesarean section in heterozygous factor V Leiden mutation evidenced post partum is reported. The patient developed extensive phlebothrombosis in both legs on postoperative day three despite preventive thrombosis treatment with low-molecular heparin. She also suffered from short-term incomplete paresis of her left arm and epileptic seizure with typical grand mal symptoms. MRI showed partial thrombosis of the superior sagittal sinus and the transverse sinus.

[Polymorphism of GPIIIA platelet glycoprotein gene PIA1/A2 compared to plasma hemostasis in myocardial infarction patients]

AIM

To investigate gene PIA1/A2 polymorphism and some parameters of plasma hemostasis in postmyocardial infarction (PMI) patients with chronic cardiac failure (CCF).

MATERIALS AND METHODS

A total of 58 PMI patients with CCF, pulmonary artery thromboembolism (PATE), phlebothrombosis (PT) were examined. The age of the patients ranged from 24 to 84 years. Polymorphism of platelet glycoprotein GPIIIa gene was assessed according to the standard PCR-RFLP.

RESULTS

Occurrence of genotypes PIA1/A2, PIA1/A2 was 70.8 and 29.2%, respectively; of allele PIA1 and PIA2 84.5 and 15.5%, respectively. In PMI patients genotype PIA1/A1 occurred in 71.7% of cases, genotype PIA1/A2--in 28.3%. Incidence of alleles was: 84.0% (PIA1), 16.0% (PIA2). PATE patients had genotype PIA1/A1, PT patients had distribution of the genotypes 50.0% and 50.0%, respectively. In patients who had suffered MI at the age under 45 years prevalence of the genotypes was 63.2% PIA1A1, 36.8% PIA1A2, of alleles 83.6% PIA1, 16.4% PIA2. In patients with a history of MI at the age over 50 the incidence of the genotypes and alleles was, respectively, 75.0% PIA1A1, 25.0% PIA1A2, 87.7% PIA1, 12.3% PIA2. Patients with genotype PIA1/A2 had a significantly higher fibrinogen than PIA1A1. Concentration of soluble fibrin monomeric complex was higher in patients with genotype PIA1/A2 reflecting activation of intravascular clotting. AT-III decrease by 5.4% indicated lower anticoagulant activity in patients with genotype PIA1A2.

CONCLUSION

In patients with MI at the age under 45 years gene PIA1A2 and allel PIA2 occurred more frequently than in patients who had MI at older age. Allele PIA2 was associated with the risk of MI onset at young age. It is suggested that patients with genotype PIA1/A2 are at higher risk of thrombotic conditions, of coronary artery thrombosis in particular, than patients with genotype PIA1/A1.

[20210G/A mutation of prothrombin gene in a patient with deep venous thrombosis ad pulmonary embolism without other risk factors of thrombosis]

A new genetic anomaly predisposing to venous thrombosis was described in 1996, namely the transition of guanine (G) to adenine (A) at position 20210 in the 3-untranslated region of the prothrombin gene. This mutation is associated with high levels of plasma prothrombin and increased risk of thrombotic events in the venous system. We report the case of a man who, lacking known risk factors for thrombosis, suffered a massive pulmonary embolism and deep venous thrombosis in both lower legs. Thrombophilic analysis confirmed that the patient and close relatives were carriers of the heterozygotic 20210G/A variant of the prothrombin gene. Two relatives with the genetic defect had also suffered some type of deep venous thrombosis.

The relationship between polymorphisms in the endothelial cell nitric oxide synthase gene and the platelet GPIIIa gene with myocardial infarction and venous thromboembolism in African Americans

STUDY OBJECTIVES

To determine whether the polymorphic dinucleotide repeats found in intron 4 of the endothelial cell nitric oxide synthase (ecNOS) gene and the platelet GPIIIa PLA(1)/A(2) polymorphism are associated with myocardial infarction (MI) and venous thromboembolism (VTE) in African Americans. Because these two genes may interact physiologically, the third objective was to determine if there was a relationship between the polymorphisms with respect to MI and VTE.

DESIGN

A hospital-based case-control study. After informed consent was obtained, blood used for DNA extraction was drawn from the subjects.

SETTING

The study was conducted in the Anticoagulant Clinic and the Cardiology Clinic at Grady Memorial Hospital in Atlanta Georgia.

PATIENTS

Subjects were recruited from African-American patients with a reported history of MI (n = 110) or VTE (n = 91). Control subjects (n = 185) without a history of cardiovascular or venous disease were recruited from an outpatient clinic.

MEASUREMENTS AND RESULTS

The 393 ecNOS allele was more common among MI cases (36%; p = 0.01) and VTE cases (35%; p = 0.04) than among control subjects (26%). There was no association between the GPIIIa genotypes and either MI or VTE. However, among the MI subjects, there was a strong association between the ecNOS 393/393 genotype and the Pl(A2) allele. It was also found that the frequency of the 393 allele was higher in African-American persons (0.26) compared with what has been reported for Australian Caucasians (0. 14) and Japanese (0.10).

CONCLUSIONS

The 393 allele but not the Pl(A2) allele was significantly associated with both MI and VTE in African Americans. Homozygosity for the 393 allele was significantly associated to the diagnosis of MI prior to the age of 45. The combination of the 393 allele and a Pl(A2) allele was also highly associated with MI. The frequency of the 393 allele was significantly higher in African Americans than what has been reported for other populations. This study furthers not only extends the association of the 393 allele to VTE but has demonstrated an interaction with the Pl(A2) allele with respect to MI.

[Activated protein C resistance in patients with central retinal vein occlusion in comparison to patients with a history of deep-vein thrombosis and a healthy control group]

BACKGROUND

The recently described "APC resistance" caused by a mutant form of factor V (factor V Leiden) is the most frequent cause of hereditary thrombosis. This study was carried out to investigate the association between activated protein C resistance and central retinal vein occlusion (CRVO). We evaluated the prevalence of APC resistance in patients with CRVO, patients with a history of deep-vein thrombosis, and a healthy control group.

PATIENTS AND METHODS

We examined 107 patients with CRVO, 112 patients with deep-vein thrombosis and 70 healthy individuals. The test performed was a modified APC-resistance assay using factor V-deficient plasma.

RESULTS

We identified APC resistance in 5.6 % of patients with CRVO and in 5.7 % of the control group. All carriers were heterozygous. In the deep-vein thrombosis group 23.2 % tested positive for APC resistance. Four patients were homozygous and 22 were heterozygous carriers.

CONCLUSION

These results indicate that APC resistance has no major role in the pathogenesis of CRVO. Routine testing for the presence of factor V Leiden mutant in CRVO is not necessary.

[APC resistance--most frequent familial thrombophilia]

Two sisters having suffered from deep vein thrombosis while taking oral contraceptives are presented. Investigation for thrombophilia in 1993 was unrevealing. After the discovery of activated protein C (APC) resistance caused by the factor V R506Q (FV Leiden) mutation in 1993/1994, reinvestigation showed homozygous FV Leiden mutation in both sisters. APC resistance is the most frequent hereditary thrombophilia known so far. Diagnosis, prevalence and clinical significance of this thrombophilic defect are shortly discussed.

The O blood group protects against venous thromboembolism in individuals with the factor V Leiden but not the prothrombin (factor II G20210A) mutation

We investigated the influence of the ABO blood group in the observed prevalences of the recently described factor V R506Q and factor II G20210A mutations in a thrombotic population. We determined the ABO blood group in a sample of 178 unselected patients (aged 17-83 years), diagnosed at our center with deep vein thrombosis or pulmonary embolism. The results of this study show a high prevalence of thrombosis in the non-O blood group. In the general population, the prevalence as a fraction of the O blood group was 2.69 (confidence interval 1.90-3.82). Of the factor V R506Q carriers (n = 28), only one had O group blood and 27 of 28 were non-O (24 A, one B and two AB). However, within the group of factor II G20210A carriers (n = 17), seven had O, nine A and one B type blood. The prevalence of the factor V R506Q mutation within the O blood group was 2.4% (one of 42), significantly lower than in the A group (23.3%, 24 of 103; P = 0.002), or in the overall non-O group (19.9%, 27 of 136; P = 0.006). This prevalence was similar to that observed previously in the non-thrombotic population in our area (3.5%; P = 0.9). We analyzed the clotting activity of factor VIII and we found higher levels in the non-O group (1.78+/-0.61 U/ml) than in the O blood group (1.30+/-0.51 U/ ml; P < 0.0001). We speculate that factor Va in individuals with the factor V Leiden mutation could interact with the high levels of factor VIII clotting activity as a necessary cofactor.

Homocyst(e)ine, vitamins and genetic interactions in vascular disease

Blood homocyst(e)ine levels are an important, independent and frequent risk factor for clinical atherosclerosis and venous thrombosis. Folic acid, vitamins B6 and B12, renal and thyroid functions, certain medications and certain genotypes are known to modulate plasma homocyst(e)ine levels. Intake of B vitamins through diet, supplementation and fortified foods effectively reduces homocyst(e)ine concentration and thus may reduce the risk of cardiovascular disease. This is true even in individuals who are genetically predisposed to hyperhomocyst(e)inemia. Randomized clinical trials are needed to investigate these effects further.

Is the prevalence of the factor V Leiden mutation in patients with pulmonary embolism and deep vein thrombosis really different?

INTRODUCTION

Previous investigations have suggested a lower prevalence of the factor V Leiden mutation in patients with pulmonary embolism, as compared to patients with deep leg vein thrombosis.

METHODS

We studied unselected patients with pulmonary embolism, in whom we also assessed the presence of deep vein thrombosis by ultrasonography. We assessed the prevalence of heterozygosity for the factor V Leiden mutation and compared the outcome of patients with a normal ultrasound (primary pulmonary embolism) to those with an abnormal ultrasound (combined form of venous thromboembolism). Furthermore, we performed a literature search to identify all articles regarding the prevalence of heterozygous factor V Leiden mutation in patients with primary deep vein thrombosis, primary pulmonary embolism and a combined form of venous thromboembolism. We calculated a (common) odds ratio for these 3 manifestations of venous thromboembolism, including the current findings.

RESULTS

In 92 patients with proven pulmonary embolism, 25 (27%) had also an abnormal ultrasound. In these patients, the prevalence of the factor V Leiden mutation was 24% (95% CI 9%-45%), whereas the mutation was present in 5 of 67 patients with primary pulmonary embolism (7%; 95% CI 2%-16%). The literature analysis indicated the common odds ratio for the presence of heterozygous factor V Leiden mutation in patients with primary deep vein thrombosis, primary pulmonary embolism and the combined form of venous thromboembolism to be 7.9 (95% CI 5-12), 3.5 (95% CI 2-6) and 6.8 (95% CI 3-14), respectively.

CONCLUSION

In patients with primary pulmonary embolism the prevalence of the factor V Leiden mutation appears to be half of that reported in patients with primary deep vein thrombosis. The mechanism remains unclear.

Resistance to activated protein C as an etiology for stroke in a young adult: a case report

Resistance to activated protein C (R-APC) is an inherited, autosomal dominant, coagulation abnormality that is increasingly recognized as an important etiology for thromboembolic disease and stroke in young adults. This report describes the case of a 27-year-old woman taking oral contraceptives who experienced an acute thrombotic right hemispheric stroke. Three days after rehabilitation admission (33 days after stroke) she developed a left femoral deep venous thrombosis (DVT) despite appropriate prophylaxis. Further diagnostic workup for the stroke and DVT identified R-APC, possibly exacerbated by oral contraceptives, as the etiology. Hematology consultation recommended lifetime anticoagulation with warfarin. The patient's family history revealed that a 19-year-old cousin had died of a stroke several years earlier. Several months after discharge, an acute DVT occurred in the patient's 28-year-old brother, who tested positive for factor V Leiden, a genetic abnormality closely associated with R-APC. A thrombotic stroke occurred in her grandfather a few months later, but he was not tested. Her father demonstrated a "borderline" positive R-APC test and probably represents the genetic link. Indications for patient and family screening regarding R-APC and other forms of hereditary thrombophilia and implications for rehabilitation medicine physicians are discussed.

Venous thrombosis in older people: prevalence of the factor V gene mutation Q506

OBJECTIVES

Old age is usually considered to be a risk factor for venous thromboembolism, in conjunction with other factors such as heart failure, major surgery, cancer, long-term immobilization, and antiphospholipid antibodies. Genetic risk factors, especially inherited deficiencies in coagulation inhibitors, also play a role in the pathogenesis of thrombosis, but these are usually diagnosed in thrombophilic patients before the age of 50. The factor V Q506 mutation, responsible for activated protein C resistance, was recently linked to thromboembolic disease. We therefore investigated the prevalence of biological risk factors in older hospital patients with venous thromboembolism.

DESIGN

A 2-year study period.

SETTING

Ivry sur Seine (Paris), France.

PARTICIPANTS

Seventy-nine geriatric patients (60 women and 19 men, mean age 83+/-6.8 years, range 70-102 years) who had had at least one proven episode of venous thromboembolism were enrolled over a 2-year period.

MEASUREMENTS

Lupus anticoagulant and antithrombin (AT), protein C (PC), and protein S (PS) levels were determined in plasma. The factor V Q506 mutation was detected on genomic DNA.

RESULTS

Lupus anticoagulant was detected in two women, one of whom also had a high level of anticardiolipin IgG, leading to the diagnosis of an antiphospholipid syndrome. No hereditary deficiency in AT, PC, or PS was found, but one patient had an acquired AT deficiency. Interestingly, nine of the 79 patients (11.4%, six women and three men) were heterozygous for the factor V Q506 mutation, although none were homozygous. The only major risk factor for thrombosis identified in these patients was prolonged immobilization in four cases. Four of the nine patients who were heterozygous for the factor V Q506 mutation had recurrent thromboembolism, and two of these patients had been immobilized for long periods.

CONCLUSIONS

This study confirms that hereditary deficiencies in coagulation inhibitors, and the lupus anticoagulant, are rarely involved in the pathogenesis of venous thromboembolism in older subjects. In contrast, the factor V Q506 mutation was frequently associated with thrombosis (11.4% of our patients) and should, therefore, be considered an important risk factor in the older people.

4G/5G polymorphism of PAI-1 gene promoter and fibrinolytic capacity in patients with deep vein thrombosis

A deletion/insertion polymorphism (4G or 5G) in the promoter of the plasminogen activator inhibitor type 1 gene has been suggested to be involved in regulation of the synthesis of the inhibitor, the 4G allele being associated with enhanced gene expression. A relationship between 4G/5G polymorphism and PAI-1 levels was found in patients with cardiovascular and metabolic diseases, but not in healthy subjects. In the present work we studied the distribution of PAI-1 4G/5G genotype and its relation to fibrinolytic capacity in 70 unrelated patients with deep vein thrombosis. Each patient was assayed before and after 20 min. Venous occlusion for euglobulin lysis time, t-PA antigen and activity, and PAI-1 antigen and activity. The prevalence of 5G homozygous carriers was significantly lower in patients than in controls (10% vs. 26%, p=0.009). The 5G allele frequency was reduced, even though not significantly, in DVT patients compared to healthy subjects (0.40 vs. 0.51, respectively). In the patient group, the mean PAI-1 antigen and activity levels were significantly higher than among controls and related to the 4G/5G polymorphism. In patients with 4G/5G and 4G/4G genotype a significant correlation was found between PAI-1 levels and the global fibrinolytic activity as evaluated by euglobulin lysis time. The prevalence of a reduced fibrinolytic potential due to PAI-1 excess was 45.7% among DVT patients. Moreover, the prevalence of PAI-1 induced hypofibrinolysis was strongly related to PAI-1 polymorphism, since it was significantly lower in 5G homozygous patients (28.6%) than in both 4G/5G carriers (55.3%, p <0.001) and 4G homozygous patients (57.9%, p <0.001). In conclusion, in patients with deep vein thrombosis the 4G polymorphism of PAI-1 gene promoter may influence the expression of PAI-1 and it should be taken into consideration as a facilitating condition for pathological fibrinolysis together with other environmental and genetic factors. Whether this has any significance in regard to the pathogenesis of venous thrombosis remains to be proven.

The results of diagnostic studies for thrombophilia in a large group of patients with a personal or family history of thrombosis

The range of tests used in the evaluation of thrombophilia has been altered by the recent recognition of common genetic defects predisposing to thrombosis such as factor VLeiden (FVR506Q), enzyme deficiencies causing hyperhomocysteinemia, and improvement in the sensitivity and utilization of assays for antiphospholipid antibodies. In this study, the outcomes of laboratory evaluation of 402 patients with thrombophilia were reviewed and correlated with clinical data. A predisposing factor was present (positive diagnosis, group A) in 110 patients (27%), the test results of 111 patients (28%) could not be definitively interpreted (equivocal results, group B), and the test results of 181 (45%) were normal (group C). The median age of the group A patients was 48 years (range, 3.7-88 years), suggesting that evaluation of patients over the age of 50 is worthwhile. Of the 110 patients in group A, 84% had single defects and 16% had combined defects. The most common defect was factor VLeiden (44 patients). Equal numbers of patients presenting with arterial and venous thromboses were evaluated. Patients with arterial events were less likely to have a definable laboratory defect (33 of 132 [25%]) than were those with venous events (50 of 136 [37%]). Factor VLeiden was the most frequent finding in patients with venous events, and lupus anticoagulant or anticardiolipin antibodies were the most frequent findings in patients with arterial events. Positive diagnoses were made in patients on anticoagulants, indicating that this should not preclude investigation. Our study confirms the need for thorough evaluation to assess thrombotic risk, and it reflects the impact of newly identified thrombophilic disorders on the expected outcome of laboratory evaluation for thrombophilia.

A patient homozygous for mutation 20210A in the prothrombin gene with venous thrombosis and transient ischemic attacks of thrombotic origin

It is well established that genetic disorders interact with environmental factors to cause thrombotic diseases. Therefore, antithrombin, protein C, protein S deficiencies and the more recently described factor V Leiden and prothrombin mutations are currently been investigated to explain some thrombophilic states. We report the case of a 63-year-old man who developed two transient ischemic attacks and two years later an extensive femoro-iliac venous thrombosis. He was genotyped as FV R506Q negative and FII G20210A positive in homozygous state (FII 20210AA).

[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.