Protein C and protein S deficiencies are the most important risk factors associated with thrombosis in Chinese venous thrombophilic patients in Taiwan

Acute liver failure as initial presentation in a Chinese patient with Budd-Chiari syndrome due to protein C deficiency: A case report and literature review

Acute liver failure is an uncommon presentation in the clinic. Common causes for acute liver failure include viral hepatitis and drug-related hepatotoxicity. However, acute liver failure due to Budd-Chiari syndrome is rare. This case highlights the importance of necessary constrast-enhanced imaging studies to rule out vascular etiologies of acute liver failure, in addition to common causes like viral or drug-induced hepatic failure. We present a case of a male Chinese patient who presented with nausea, vomiting, fatigue, and fever after eating a large amount of fatty food. Six days after hospitalization, the patient developed acute liver failure and hepatic encephalopathy. Contrast-enhanced computerized tomography and ultrasound examinations revealed thromboses in the hepatic veins and inferior vena cava. Further testing also showed decreased protein C activity. Therefore, a diagnosis of Budd-Chiari syndrome secondary to protein C deficiency was made. He received supportive care and a transjugular intrahepatic portal shunt. Hepatic function, coagulation panel results, and clinical presentations gradually returned to normal. Budd-Chiari syndrome from protein C deficiency could be a rare but valid cause of acute liver failure in Chinese patients.

Development and validation of a new risk assessment model for immunomodulatory drug-associated venous thrombosis among Chinese patients with multiple myeloma

BACKGROUND

Individuals with multiple myeloma (MM) receiving immunomodulatory drugs (IMiDs) are at risk of developing venous thromboembolism (VTE), a serious complication. There is no established clinical model for predicting VTE in the Chinese population. We develop a new risk assessment model (RAM) for IMiD-associated VTE in Chinese MM patients.

METHODS

We retrospectively selected 1334 consecutive MM patients receiving IMiDs from 16 medical centers in China and classified them randomly into the derivation and validation cohorts. A multivariate Cox regression model was used for analysis.

RESULTS

The overall incidence of IMiD-related VTE in Chinese MM patients was 6.1%. Independent predictive factors of VTE (diabetes, ECOG performance status, erythropoietin-stimulating agent use, dexamethasone use, and VTE history or family history of thrombosis) were identified and merged to develop the RAM. The model identified approximately 30% of the patients in each cohort at high risk for VTE. The hazard ratios (HRs) were 6.08 (P < 0.001) and 6.23 (P < 0.001) for the high-risk subcohort and the low-risk subcohort, respectively, within both the derivation and validation cohorts. The RAM achieved satisfactory discrimination with a C statistic of 0.64. The stratification approach of the IMWG guidelines yielded respective HRs of 1.77 (P = 0.053) and 1.81 (P = 0.063). The stratification approach of the SAVED score resulted in HRs of 3.23 (P = 0.248) and 1.65 (P = 0.622), respectively. The IMWG guideline and the SAVED score-based method yielded C statistics of 0.58 and 0.51, respectively.

CONCLUSIONS

The new RAM outperformed the IMWG guidelines and the SAVED score and could potentially guide the VTE prophylaxis strategy for Chinese MM patients.

Evaluation of prothrombotic risk of two PROC hotspot mutations (Arg189Trp and Lys193del) in Chinese population: a retrospective study

BACKGROUND

R189W and K193del of protein C (PC) were hotspot mutations in Chinese population with venous thromboembolism (VTE), but almost two-thirds of patients with above mutations coexisting with other genetically or aquiredly prothrombotic risk factors. The aim of this study is to clarify the independent contributions of R189W or K193del to VTE risk.

METHODS

490 unrelated patients with a personal history of VTE and 410 healthy participants were enrolled in this study. Data of their demographics, family history, genetic and acquired thrombosis risk factors were collected and statistically analyzed.

RESULTS

PC R189W and K193del were identified in 3/410 (0.7%) and 7/410 (1.7%) healthy controls, and in 27/490 (5.5%) and 43/490 (8.8%) patients with VTE, respectively. Notably, about 70% of these mutant carriers combined with other genetic or acquired thrombophilic factors. After adjustment for age, gender, other inherited and acquired risk factors, we demonstrated that R189W and K193del were associated with 5.781-fold and 4.365-fold increased risk of VTE, respectively, which were significantly lower than the prothrombotic risk of anticoagulant deficiencies induced from rare mutations. Independent R189W or K193del mutation was not associated with earlier first-onset age as well as higher recurrent rate of VTE. However, combination of other genetic or acquired thrombophilic factors had supra-additive effects on those consequences. The more additional risk factors the patients had, the younger first-onset ages and higher risk of recurrence would be.

CONCLUSIONS

As the most frequent mutations for PC deficiency in Chinese population, both R189W and K193del mutations had limited independent contributions to VTE development compared with other rare mutations in PROC gene, but may act in concert with other genetic defects or acquired thrombotic risk factors to produce the final severe phenotype.

The Risk of Venous Thromboembolism after Thoracolumbar Spine Surgery: A Population-Based Cohort Study

Background: Although venous thromboembolism (VTE) is rare, including deep vein thrombosis (DVT) and pulmonary embolism (PE), it is a catastrophic complication after spinal surgery. This study was aimed to investigate the risk factors and incidence of VTE after thoracolumbar spine surgery (TLSS). Methods: We retrieved the data of 8697 patients >20 years old who underwent TLSS between 2000 and 2013 from Taiwan’s Longitudinal Health Insurance Database 2000. Each patient was randomly frequency-matched with four individuals who did not undergo TLSS by age, sex, and index year (the control group). Results: The incidence rates of VTE in the TLSS and control groups were 1.84 and 0.69 per 1000 person-years, respectively. The TLSS group had a higher VTE risk (adjusted HR (aHR): 2.13, 95% confidence interval [95%CI]: 1.41−3.21), DVT (aHR: 2.20, 95%CI: 1.40−3.46), and PE (aHR: 1.60, 95%CI: 0.68−3.78) than the control group. The correlated risk factors of VTE included older age (50−64 years: aHR: 2.16, 95%CI: 1.14−4.09; ≥65 years: aHR: 3.18, 95%CI: 1.65−6.13), a history of cancer (aHR: 2.96, 95%CI: 1.58−5.54), heart failure (aHR: 2.19, 95%CI: 1.27−3.78), and chronic kidney disease (aHR: 1.83, 95%CI: 1.18−2.83). Conclusions: The overall VTE risk following TLSS was less than 2% but correlated with certain risk factors. This information could help the spine surgeon help the patient prevent this fatal complication.

Benefits and risks of low molecular weight heparin use on reproductive outcomes: A retrospective cohort study

OBJECTIVE

Low molecular weight heparin (LMWH) has been given to reproductive-age women with various indications. This study aims to assess the benefits and risks of such use.

MATERIALS AND METHODS

We retrospectively reviewed data (n = 204) between Jan 2016 and May 2019. Logistic regression analysis was conducted to evaluate the correlation between indications and reproductive outcomes.

RESULTS

LMWH use had higher odds of live birth in women less than 30 years of age (OR: 4.98; 95% CI = 1.13-21.98; p = 0.034) and with protein S deficiency (OR: 3.90; 95% CI = 1.77-8.59; p = 0.001). For the subgroup of recurrent pregnant loss, LMWH use was only advantageous to women with protein S deficiency (OR: 2.45; 95%:1.01-5.97; p = 0.048). Risks such as preterm delivery, small-for-gestational-age, placental abruption, antepartum/postpartum hemorrhage were not significantly increased among subgroups. Women treated with LMWH and who had successful live births (n = 171) had a slightly increased risk of postpartum hemorrhage compared to controls (n = 8058) during this period in our institution (2.9% vs 1.2%, p < 0.001).

CONCLUSION

LMWH administration produces a higher chance of live-birth to women younger than 30 years of age or with protein S deficiency. However, risk of postpartum hemorrhage is increased.

Protein C deficiency (a novel mutation: ala291Thr) with systemic lupus erythematosus leads to the deep vein thrombosis

: The current study aims to explore the phenotype and genotype of a mutation Ala291Thr, which responsible for type I protein C (PC) deficiency in a Chinese woman. The PROC antigen was tested with chromogenic substrate method. PROC gene were amplified by PCR with direct sequencing. Bioinformatics and model analysis were used to study the harm of the mutation. PC activity (PC: A) levels of three members were reduced to 39, 57 and 56%, respectively, PC: antigen was decreased parallelly same as PC: A. Sequencing analysis showed proband with a novel heterozygous c.997G>A point mutation in exon 9 of PROC gene resulting in Ala291Thr. The Ala291Thr mutation is responsible for the decrease of PC: A, which is cross-reacting material negative deficiency and the first reported in the world. This mutation alone may not have significant clinical symptoms, whereas it will cause deep vein thrombosis when combined with systemic lupus erythematosus.

Hemodynamic change and affecting factors after shoulder arthroplasty in the Asian population

BACKGROUND

This retrospective study was designed to compare the hemodynamics among the types of shoulder arthroplasty and to evaluate predictors of transfusion in the Asian population.

METHODS

A total of 212 shoulder arthroplasties (26 fracture hemiarthroplasty (fHA), 49 anatomical total shoulder arthroplasty (aTSA), 132 reverse total shoulder arthroplasty (rTSA), and 5 revision surgery) from August 2004 to January 2016 were retrospectively reviewed. Demographics, surgical factors, and perioperative hemodynamic factors among the types of arthroplasty were compared. Multivariate analysis was conducted to determine predictors of transfusion.

RESULTS

Preoperative hemoglobin and hematocrit levels were lower in the fracture hemiarthroplasty group (p < 0.001, 0.001). The overall transfusion rate of shoulder arthroplasties in Asian population was 11.3%, and transfusion rate was significantly different among the types of arthroplasty (fHA 30.8%, aTSA 10.2%, rTSA 7.6%, revision 20.0%; p = 0.010). The predictors of transfusion were preoperative hemoglobin levels <12.15 g/dL (OR = 7.404, 95% C.I. 2.420-22.653, p < 0.001) and <10.0 g/dL at postoperative day 1 (OR = 5.499, 95% C.I. 1.929-15.671, p = 0.001).

CONCLUSION

The best predictors of transfusion were hemoglobin levels of perioperative periods, furthermore, total amount of drainage could not represent the quantity of perioperative hemorrhage. Therefore, careful monitoring of hemoglobin level is more crucial than monitoring the amount of drainage. Hemodynamics according to the type of arthroplasty should be considered in shoulder arthroplasty.

LEVEL OF EVIDENCE

Level IV, retrospective case series.

Diagnostic challenge of the newborn patients with heritable protein C deficiency

ABSTARCT

OBJECTIVE: The diagnosis of neonatal-onset protein C (PC) deficiency is challenging. This study aimed to establish the neonatal screening of heritable PC deficiency in Japan.

STUDY DESIGN

We determined the changes in plasma activity levels of PC and protein S (PS) in healthy neonates, and studied newborn patients with PROC mutation in the Japanese registry.

RESULT

Physiological PC and PS levels increased with wide range. The PC/PS-activity ratios converged after birth. The PC/PS-activity ratios of 19 patients with biallelic mutations, but not, 9 with monoallelic mutation, were lower than those of 13 without mutation. The logistic regression analyses established a formula including two significant variables of PC activity (cut-off < 10%, odds ratio = 30.0) and PC/PS-activity ratio (cut-off < 0.35, odds ratio = 22.7), with 93% sensitivity and 44% specificity for determining patients with mutation(s).

CONCLUSION

The PC/PS-activity ratio is an effective parameter for the genetic screening of neonatal-onset PC-deficiency in Japanese population.

High prevalence of factor V Leiden and prothrombin G20101A mutations in Kashmiri patients with venous thromboembolism

AIM

The genetic variants of the factor V (G1691A), prothrombin (G20210A) and MTHFR (C677T) genes have been widely implicated as inherited risk factors for developing venous thrombosis. This study was undertaken to reveal the frequency of these mutations in Kashmiri patients with venous thromboembolism.

METHODOLOGY

A case-control study was designed with 250 VTE patients and 250 healthy controls. The mutations were analysed using ARMS-PCR and PCR-RFLP approach.

RESULT

The factor V Leiden G1691A mutation was found in 17/250 (6.8%) VTE patients and prothrombin G20210A mutation was found in 7/250 (2.8%) VTE patients while no mutation was found in any of the healthy controls. Both the mutations were found to be significantly associated with the increased risk of VTE (p = 0.0001 and 0.0150 respectively) while no association of VTE risk with MTHFR C677T polymorphism was found (p = 0.53).

CONCLUSION

The increased frequency of factor V Leiden G1691A and prothrombin G20210A mutation in VTE patients indicates a significant role of these mutations in the development of VTE in our population. We therefore suggest the routine screening of these two mutations as thrombophilic markers in Kashmiri patients with venous thromboembolism.

The diagnosis and treatment of venous thromboembolism in asian patients

Although the incidence of venous thromboembolism (VTE) in Asian populations is lower than in Western countries, the overall burden of VTE in Asia has been considerably underestimated. Factors that may explain the lower prevalence of VTE in Asian populations relative to Western populations include the limited availability of epidemiological data in Asia, ethnic differences in the genetic predisposition to VTE, underdiagnoses, low awareness toward thrombotic disease, and possibly less symptomatic VTE in Asian patients. The clinical assessment, diagnostic testing, and therapeutic considerations for VTE are, in general, the same in Asian populations as they are in Western populations. The management of VTE is based upon balancing the treatment benefits against the risk of bleeding. This is an especially important consideration for Asian populations because of increased risk of intracranial hemorrhage with vitamin K antagonists. Non-vitamin K antagonist oral anticoagulants have shown advantages over current treatment modalities with respect to bleeding outcomes in major phase 3 clinical trials, including in Asian populations. Although anticoagulant therapy has been shown to reduce the risk of postoperative VTE in Western populations, VTE prophylaxis is not administered routinely in Asian countries. Despite advances in the management of VTE, data in Asian populations on the incidence, prevalence, recurrence, risk factors, and management of bleeding complications are limited and there is need for increased awareness. To that end, this review summarizes the available data on the epidemiology, risk stratification, diagnosis, and treatment considerations in the management of VTE in Asia.

Justification of routine venous thromboembolism prophylaxis in head and neck cancer reconstructive surgery

BACKGROUND

Venous thromboembolism (VTE) is a preventable complication in which early ambulation is expected after head and neck surgery. Thus, the role of VTE prophylaxis is questionable and needs further assessment. The purpose of this study was to specify the relative contributing risk factors for patients who underwent head and neck cancer ablation with immediate reconstruction.

METHODS

A retrospective analysis was conducted of consecutive head and neck cancer ablations with immediate reconstructions between 2008 and 2013. Dextran and prostaglandin E2 (PGE2) were routinely given as flap thromboprophylaxis. Logistic regression was applied to analyze the potentially significant risk factors.

RESULTS

Of 1953 subjects, the incidence of symptomatic VTE was 2.2% with 0.1% mortality rate. Prolonged surgery (>592.5 minutes; P = .048), immobilization (>4 days; P = .019), and subjects without postoperative flap thromboprophylaxis (P = .002) are significant risk factors for VTE development.

CONCLUSION

Our flap thromboprophylaxis regime might have played a crucial role in keeping the incidence of VTE low. Despite prolonged immobilization in fibula flap reconstruction, the incidence of VTE remained low when flap thromboprophylaxis was given.

Review article: the aetiology of primary Budd-Chiari syndrome - differences between the West and China

BACKGROUND

China may have the largest number of Budd-Chiari syndrome (BCS) cases in the world (at least 1914 original papers were published, and at least 20 191 BCS patients were reported). Considering the discrepancy in the clinical profiles and preferred treatment selection of primary BCS between the West and China, understanding its aetiology in these two different regions is very important.

AIM

To review the data from large cohort studies and meta-analyses to illustrate the epidemiology of risk factors for BCS in the West and China.

METHODS

Relevant papers were identified by major English- and Chinese-language databases, conference abstracts, and by manual search.

RESULTS

Risk factors reviewed include myeloproliferative neoplasms (MPNs) and their related gene mutations, anti-phospholipid syndrome, paroxysmal nocturnal haemoglobinuria (PNH), hyperhomocysteinaemia and 5,10-methylenetetrahydrofolate reductase (MTHFR) C677T mutation, factor V Leiden (FVL) and prothrombin G20210A mutations, inherited anti-thrombin, protein C and protein S deficiencies, pregnancy and puerperium, poverty, and family history.

CONCLUSIONS

We examined the differences in the aetiological distribution of BCS between the West and China. Several recommendations should be considered in Chinese BCS patients: (i) screening for hyperhomocysteinaemia and MTHFR mutation should be regularly performed; (ii) screening for MPNs, PNH, and anti-phospholipid syndrome should be selectively performed; (iii) inherited anti-thrombin, protein C, and protein S deficiencies should be actively explored; (iv) screening for FVL and prothrombin G20210A mutations may be unnecessary; and (v) the clinical significance of pregnancy and puerperium, poverty with bacterial infections and unsanitary environments, and family history as possible risk factors should never be neglected.

Low-molecular-weight-heparin can benefit women with recurrent pregnancy loss and sole protein S deficiency: a historical control cohort study from Taiwan

BACKGROUND

Heritable thrombophilias are assumed important etiologies for recurrent pregnancy loss. Unlike in the Caucasian populations, protein S and protein C deficiencies, instead of Factor V Lieden and Prothrombin mutations, are relatively common in the Han Chinese population. In this study we aimed to investigate the therapeutic effect of low molecular weight heparin upon women with recurrent pregnancy loss and documented protein S deficiency.

METHODS

During 2011-2016, 68 women with recurrent pregnancy loss (RPL) and protein S deficiency (both the free antigen and function of protein S were reduced) were initially enrolled. All the women must have experienced at least three recurrent miscarriages. After excluding those carrying balanced translocation, medical condition such as diabetes mellitus, chronic hypertension, and autoimmune disorders (including systemic lupus erythematosus and anti-phospholipid syndrome), coexisting thrombophilias other than persistent protein S deficiency (including transient low protein S level, protein C deficiency, and antithrombin III), only 51 women with RPL and sole protein S deficiency were enrolled. Initially they were prescribed low dose Aspirin (ASA: 100 mg/day) and unfortunately there were still 39 women ended up again with early pregnancy loss (12 livebirths were achieved though). Low-molecular-weight-heparin (LMWH) was given for the 39 women in a dose of 1 mg/Kg every 12 h from the day when the next clinical pregnancy was confirmed to the timing at least 24 h before delivery. The perinatal outcomes were assessed.

RESULTS

Of 50 treatment subjects performed for the 39 women (i.e. 11 women enrolled twice for two pregnancies), 46 singletons and one twin achieved livebirths. The successful live-birth rate in the whole series was 94 % (47/50). Nineteen livebirths delivered vaginally whereas 28 delivered by cesarean section. The cesarean delivery rate is thus 59.57 %. Emergent deliveries occurred in 3 but no postpartum hemorrhage had been noted.

CONCLUSIONS

Our pilot study in Taiwan, an East Asian population, indicated anti-coagulation therapy is of benefit to women with recurrent pregnancy loss who had documented sole protein S deficiency.

TRIAL REGISTRATION

ISRCTN64574169. Retrospectively registered 29 Jun 2016.

Genetic Risk Factors of Venous Thromboembolism in the East Algerian Population

Many genetic risk factors have been identified for causing venous thromboembolism (VTE). Most of them affect the function of natural anticoagulant pathways, particularly the protein C system, although recent studies suggest a role of components of the hematopoietic pathway in the etiology of venous thrombosis. In this case–control study, we aimed to determine the frequency of prothrombin G20210A and factor V Leiden (FVL) G1691A polymorphisms and protein C, protein S, and antithrombin III deficiencies in the East Algerian population and to investigate whether these genetic factors are associated with VTE. On the other hand, our study tends to evaluate the status of JAK2V617F and calreticulin (CALR) mutations among these cases. The participants consisted of 121 cases with VTE and 146 healthy controls. Polymorphisms of FVL G1691A and prothrombin G20210A were genotyped by polymerase chain reaction (PCR) restriction fragment length polymorphism. JAK2-V617F and calreticulin mutations were analyzed by quantitative PCR and PCR followed by capillary electrophoresis sequencing, respectively. Protein C, protein S, and antithrombin levels were determined and then hereditary deficiencies were identified. Of all cases and controls, none was a carrier of the antithrombin III deficiency, prothrombin gene G20210A, and CALR mutations. Only 1 case reported having a positive JAK2 mutation (mutant allele burden was 15%). The FVL mutation (GA/AA) was found in 14 (11.6%) cases and 2 (1.4%) controls and it was significantly different between both the groups ( P = .001). Deficiencies of protein S and protein C were detected in 17 (18.8%) cases. The univariate analysis resulted in a significant impact of FVL (odds ratio [OR] = 9.4, 95% confidence interval [CI] = 2.1-42.3; P = .003) and of protein S deficiency (OR = 16.9, 95% CI =2.1-132.8, P = .007) on the VTE status. Both factors stayed significant after adjustment for sex and age. The OR of the protein C deficiency was slightly elevated (OR = 6.4, 95% CI = 0.7-55.5), but it did not reach the level of statistical significance ( P = .091), and it was therefore not considered as a risk factor. In conclusion, coagulant factor V gene G1691A mutation and protein S deficiency constitute important genetic risk factors in patients with VTE in Eastern Algeria. The somatic mutation of JAK2 V617F and CALR mutations are less frequent causes of VTE, thus routine testing for these mutations is not recommended.

Management of Venous Thromboembolisms: Part I. The Consensus for Deep Vein Thrombosis

Deep vein thrombosis (DVT) is a potentially catastrophic condition because thrombosis, left untreated, can result in detrimental pulmonary embolism. Yet in the absence of thrombosis, anticoagulation increases the risk of bleeding. In the existing literature, knowledge about the epidemiology of DVT is primarily based on investigations among Caucasian populations. There has been little information available about the epidemiology of DVT in Taiwan, and it is generally believed that DVT is less common in Asian patients than in Caucasian patients. However, DVT is a multifactorial disease that represents the interaction between genetic and environmental factors, and the majority of patients with incident DVT have either inherited thrombophilia or acquired risk factors. Furthermore, DVT is often overlooked. Although symptomatic DVT commonly presents with lower extremity pain, swelling and tenderness, diagnosing DVT is a clinical challenge for physicians. Such a diagnosis of DVT requires a timely systematic assessment, including the use of the Wells score and a D-dimer test to exclude low-risk patients, and imaging modalities to confirm DVT. Compression ultrasound with high sensitivity and specificity is the front-line imaging modality in the diagnostic process for patients with suspected DVT in addition to conventional invasive contrast venography. Most patients require anticoagulation therapy, which typically consists of parenteral heparin bridged to a vitamin K antagonist, with variable duration. The development of non-vitamin K oral anticoagulants has revolutionized the landscape of venous thromboembolism treatment, with 4 agents available,including rivaroxaban, dabigatran, apixaban, and edoxaban. Presently, all 4 drugs have finished their large phase III clinical trial programs and come to the clinical uses in North America and Europe. It is encouraging to note that the published data to date regarding Asian patients indicates that such new therapies are safe and efficacious. Ultimately, our efforts to improve outcomes in patients with DVT rely on the awareness in the scientific and medical community regarding the importance of DVT.

KEY WORDS

Combination therapy; Hypertension; α1-blocker.

Age-specific onset and distribution of the natural anticoagulant deficiency in pediatric thromboembolism

BACKGROUND

The early diagnosis of inherited thrombophilia in children is challenging because of the rarity and hemostatic maturation.

METHODS

We explored protein C (PC), protein S (PS), and antithrombin (AT) deficiencies in 306 thromboembolic patients aged ≤20 y using the screening of plasma activity and genetic analysis.

RESULTS

Reduced activities were determined in 122 patients (40%). Low PC patients were most frequently found in the lowest age group (0-2 y, 45%), while low PS or low AT patients were found in the highest age group (16-20 y; PS: 30% and AT: 20%). Genetic study was completed in 62 patients having no other causes of thromboembolism. Mutations were determined in 18 patients (8 PC, 8 PS, and 2 AT genes). Six of eight patients with PC gene mutation were found in age 0-2 y (75%), while six of eight patients with PS gene mutation were in 7-20 y. Two AT gene-mutated patients were older than 4 y. Four PC-deficient and two PS-deficient patients carried compound heterozygous mutations. All but one PC gene-mutated patient suffered from intracranial thromboembolism, while PS/AT gene-mutated patients mostly developed extracranial venous thromboembolism.

CONCLUSION

Stroke in low PC infants and deep vein thrombosis in low PS/AT school age children could be targeted for genetic screening of pediatric thrombophilias.

Progress in research into the genes associated with venous thromboembolism

BACKGROUND

Venous thromboembolism (VTE), including both deep vein thrombosis (DVT) and pulmonary embolism (PE), is a common, lethal disorder that affects hospitalized and non-hospitalized patients. This study aimed to review the progress in the research into VTE.

DATA SOURCES

We reviewed the studies about VTE and verified different genetic polymoriphisms of VTE.

RESULTS

The pathogenesis of VTE involves hereditary and acquired factors. Many studies indicated that the disorder of coagulation and fibirnolytic system is of utmost importance to this disease. Genetic polymoriphism-related VTE demonstrated significant differences among geographies and ethnicities.

CONCLUSION

VTE has many risk factors, but genetic factors play an important role.

Natural anticoagulants deficiency and the risk of venous thromboembolism: a meta-analysis of observational studies

INTRODUCTION

Natural anticoagulants deficiency (antithrombin [AT], protein C [PC], protein S [PS]) is a rare, but potent risk factor for venous thromboembolism (VTE). We performed a meta-analysis of observational studies evaluating the impact of inherited natural anticoagulants deficiency on VTE risk.

MATERIALS AND METHODS

Case-control and cohort studies evaluating the association of these abnormalities with VTE were systematically searched in the PubMed, Web of Science, Scopus and EMBASE databases.

RESULTS

Twenty-one studies were included in the analysis. Thirteen studies (3,452 cases and 11,562 controls) showed an increased risk of first VTE in AT deficient subjects compared to controls (OR: 16.26, 95%CI:9.90-26.70; P<0.00001). An increased risk of first VTE was also found in PC (11 studies, 2,554 cases and 9,355 controls; OR: 7.51, 95%CI:3.21-17.52; P<0.00001) and PS deficient patients (14 studies, 4,955 cases and 9,267 controls; OR: 5.37; 95%CI:2.70-10.67; P<0.00001) compared to controls. Evaluating the risk of VTE recurrence, we found a significant association with AT (4 studies, 142 cases and 1,927 controls; OR: 3.61; 95%CI:1.46-8.95; P=0.006) and with PC (2 studies, 80 cases and 546 controls; OR: 2.94; 95%CI:1.43-6.04; P=0.03), but not with PS deficiency (2 studies, 57 cases and 589 controls; OR: 2.52; 95%CI:0.89-7.16; P=0.08). Sensitivity and subgroup analyses confirmed these results. The association among natural anticoagulants deficiency and VTE was maximal for patients with unprovoked events.

CONCLUSION

The VTE risk is increased in patients with natural anticoagulants deficiency, but additional studies are warranted to better assess the risk of VTE recurrence.

Thrombotic risk factors in Chinese nonmalignant and noncirrhotic patients with portal vein thrombosis: an observational study with a systematic review of the literature

BACKGROUND

Until now, no data on the routine screening for thrombotic risk factors in Chinese nonmalignant and noncirrhotic patients with portal vein thrombosis (PVT) have been reported.

METHODS

A total of 141 nonmalignant and noncirrhotic patients with PVT who underwent screening tests for thrombotic risk factors between September 2009 and August 2012 were included in this study.

RESULTS

The JAK2 V617F mutation was found in 35 of the 141 patients tested. Neither the JAK2 exon 12 mutation nor the MPL W515 L/K mutation was found in any of the 50 patients tested. Overt myeloproliferative neoplasms (MPNs) were diagnosed in 13 patients (polycythemia vera, n=1; essential thrombocythemia, n=9; idiopathic myelofibrosis, n=3). Latent MPNs were considered in 23 patients with the JAK2 V617F mutation but without any significant abnormalities, as determined through regular blood tests. Anticardiolipin IgG antibodies were positive in none of the 136 patients tested. Paroxysmal nocturnal hemoglobinuria was not found in any of the 141 patients tested. Neither the factor V G1691A mutation nor the factor II G20210A mutation was found in any of the 72 patients tested. The C677T mutation in 5,10-methylenetetrahydrofolate reductase (MTHFR) was found in 29 of the 38 patients tested. Hyperhomocysteinemia was detected in eight of the 39 patients tested.

CONCLUSION

MPNs are an important thrombotic risk factor in Chinese patients with PVT. However, the extreme rarity of paroxysmal nocturnal hemoglobinuria, anticardiolipin IgG antibodies, and factor V G1691A and factor II G20210A mutations has precluded any support for the implementation of routine screening for these thrombotic factors in such patients. Additional case-control studies should confirm the role of the MTHFR C677T mutation and hyperhomocysteinemia in the pathogenesis of PVT.

Dysfunction of protein C anticoagulant system, main genetic risk factor for venous thromboembolism in northeast Asians

Venous thromboembolism (VTE) is a life threatening medical disorder worldwide. A great deal of evidence suggests that prevalence of VTE varies significantly among ethnic populations, with consistently lower incidence found in Asians. While the distribution of genetic risk factors may vary among races, genetic risk factors can play a major role among individuals with different genetic backgrounds. Two clinically evaluated low-frequency genetic mutations that predispose to VTE--the factor V Leiden mutation and prothrombin G20210A mutation--are found predominantly in Caucasians, and virtually never in Asians. The findings of a recent genetic study of VTE in northeast Asians, which greatly advanced our knowledge in this area, indicate that the most frequent genetic risk factors for VTE in northeast Asians can be attributed to a dysfunction of the protein C anticoagulant system. Several low-frequency genetic mutations, PROS1 p.Lys196Glu in Japanese and PROC p.Arg189Trp and p.Lys193del in Chinese, are significantly associated with increased risk for VTE, with odds ratio more than 2 through the reduced protein C anticoagulant activity. Construction of a multifactorial model based on the genetic risk factors in the protein C anticoagulant system could facilitate genetic counseling for VTE risk in these populations. The influence of prevalent genetic mutations on the risk of VTE should be further investigated in Asian countries.

The Prevalence of the Prothrombin (F2) 20210G>A Mutation in a Cohort of Sri Lankan Patients with Thromboembolic Disorders

Prothrombin (F2) 20210G>A [rs1799963 G>A] mutation is a genetic variant which predisposes to inherited thrombophilia. Highest prevalence of this rare mutation has been reported among Caucasian and Mediterranean populations with thrombophilic conditions compared to healthy controls. It is absent or occurs in a very low frequency in both thrombophilic patients and healthy controls of most South Asian populations. A previous study has demonstrated that the mutant allele is absent among Sri Lankan healthy controls. This study was conducted to determine the prevalence of the F2 20210G>A mutation among Sri Lankan patients with thrombo-embolic disorders. F2 20210G>A mutation analysis was carried out on 825 patients. These included 374 with arterial thromboembolic disorders, 303 with venous thromboembolic disorders (VTE) and 148 with pregnancy related complications. Genotyping was done using polymerase chain reaction followed by restriction fragment length polymorphism. The overall prevalence of the individuals detected with the mutation was 0.8 % (7/825) with a mutant allele frequency of 0.4 % (7/1,650), and all were heterozygotes. Further classification according to the types of thrombotic events showed a prevalence of 0.5 % (2/374), 1.3 % (4/303), and 0.7 % (1/148) respectively, in the three groups with arterial thrombosis, VTE and pregnancy complications. The respective mutant allele frequencies in the three different groups were 0.3 % (2/748), 0.7 % (4/606) and 0.3 % (1/296). Although these figures are lower than that of Caucasian and Mediterranean populations, they are relatively higher compared to other South Asian populations. Therefore, the F2 20210G>A mutant allele is not entirely absent among Sri Lankan patients with thrombo-embolic disorders.

Risk factors for thrombosis in an african population

SUMMARY

Little is known about the biological, epidemiological, and clinical risk factors for thrombosis and venous thromboembolism (VTE) among Black Africans. We undertook a study of the prevalence of VTE risk factors for thrombosis in a Senegalese population.

A three-year cross-sectional and case–control study involving 105 cases and 200 controls was conducted in various hospitals in Dakar (Senegal). Our results demonstrate that oral contraception, immobilization by casts, surgery, and blood group were significantly associated with VTE occurrence. Additionally, 16 cases and 2 controls had protein S (PS) values of less than 48.4% (M-2SD), exhibiting a highly significant difference (P < 1 × 10⁻⁴). The number of cases with a low protein C (PC) level was significantly higher than the respective number of controls. Using logistic regression methods, we established a correlation between significantly associated variables and deep venous thrombosis (DVT) occurrence. Age, obesity, sickle cell disease, and PC deficiency were not significantly associated with thrombosis. In contrast, gender, PS deficiency, varicose veins, surgery, non-O blood type, and the presence of antiphospholipid antibodies were significantly and independently associated with DVT.

These findings are extremely useful for clinical management of patients suffering from DVT and can help to reduce the high recurrence rate observed in our study.

Deficiency of antithrombin and protein C gene in 202 Chinese venous thromboembolism patients

INTRODUCTION

Antithrombin and protein C gene deficiencies are commonly inherited risk factors for VTE patients. We aim to investigate the deficiency of these two gene in 202 Chinese patients with venous thromboembolism (VTE).

METHODS

Antithrombin activity (AT: A) and protein C activity (PC: A) were measured in 202 VTE patients, and for those with unexplainable low results, PCR and direct sequencing of the related genes were carried out.

RESULTS

Deficiency levels of antithrombin and protein C gene were found to be 2% and 8%, respectively. AT or PC hereditary deficiency can be found in 10% patients with VTE.

CONCLUSION

Protein C gene deficiency might be more prevalent than AT gene deficiency in Chinese VTE patients. Functional assay combined with genetic analysis is useful in the diagnosis of inherited defects in VTE patients.

Value of D-dimer and protein S for diagnosis of portal vein thrombosis in patients with liver cirrhosis

OBJECTIVE

To investigate the value of D-dimer and protein S plasma concentrations for diagnosis of portal vein thrombosis (PVT) in patients with liver cirrhosis.

METHODS

D-dimer and protein S were quantified, PVT was diagnosed by dynamic enhanced computed tomography and liver function was classified using the Child-Pugh system. Receiver operating curve analysis was performed.

RESULTS

D-dimer increased, and protein S decreased, with decreasing liver function in the total study population (n = 188). D-dimer concentrations were significantly higher and protein S concentrations were significantly lower in patients with (n = 51) than those without PVT (n = 137). D-dimer had high specificity and negative predictive value (NPV) in Child-Pugh class A or B patients (cut-off values>0.56 mg/l and >1.18 mg/l, respectively). In class C patients>0.77 mg/l D-dimer had high sensitivity and NPV. Protein S had high sensitivity but low specificity in class A or B patients (cut-off values < 17.4 mg/l and <19.2 mg/l, respectively).

CONCLUSION

Plasma D-dimer and protein S are potential biomarkers for PVT diagnosis in patients with cirrhosis. PVT can be excluded when D-dimer is low and protein S is elevated.

Expression and functional characterisation of natural R147W and K150del variants of protein C in the Chinese population

Protein C is a vitamin K-dependent serine protease zymogen in plasma which upon activation to activated protein C (APC) by thrombin down-regulates the clotting cascade by limited proteolysis of the procoagulant cofactors Va and VIIIa. In addition to its anticoagulant activity, APC also exhibits potent cytoprotective and anti-inflammatory activities. While the anticoagulant activity of APC is enhanced by the cofactor function of protein S on membrane phospholipids, the cytoprotective intracellular signalling activity of APC requires complex formation with endothelial protein C receptor (EPCR) expressed on the vascular endothelium. Two natural variants of APC [Arg-147 to Trp substitution (R147W) and Lys-150 deletion (K150del)] have been identified in the Chinese population as hotspot mutants occurring with high frequencies of 27.8% and 13.9%, respectively, among 36 protein C-deficient subjects. The affected individuals exhibit variable thrombotic tendencies. To understand the underlying cause of the thrombotic phenotype in these patients, we expressed these two protein C variants in mammalian cells and characterised their anticoagulant and anti-inflammatory properties using established in vitro and cellular assays. Our results suggest that both R147W and K150del variants have normal amidolytic and proteolytic activities in the absence of cofactors. However, the R147W mutant exhibits ~3 times lower affinity for binding to EPCR and the K150del variant has ~2-3-fold impaired anticoagulant activity in the presence of protein S. These results provide some insight into the possible pathogenic mechanism of protein C deficiency in Chinese patients carrying these mutations.

Familial Budd-Chiari Syndrome in China: A Systematic Review of the Literature

Familial occurrence of Budd-Chiari syndrome (BCS) has been reported in scattered cases, which potentially favors the congenital theory. A review of the literature was conducted to demonstrate this phenomenon in China. PubMed, VIP, and CNKI databases were searched for studies describing at least two Chinese BCS patients from the same one family. In the 18 eligible papers, 30 siblings or first-degree relatives from 14 families were diagnosed with BCS at 9 different centers. Common clinical presentations included varices of abdominal wall and lower limbs, edema of legs, and ascites. Type and location of obstruction were similar among these patients from the same one family. Screening for BCS was conducted in 65 family members from 3 families, demonstrating that 2 asymptomatic siblings from one family were further diagnosed with BCS. Factor V Leiden mutation was found in 3 of 4 patients from one family and in one of 2 patients from another one family. Prothrombin G20210A gene mutation was found in none of the 4 patients from the 2 families. In conclusion, our study showed the possibility of familial aggregation in Chinese BCS patients, but these available data cannot support the previous hypothesis that familial BCS originates from congenital vascular malformation.

New quantitative total protein S-assay system for diagnosing protein S type II deficiency: clinical application of the screening system for protein S type II deficiency

Venous thromboembolism (VTE) incidence is rising rapidly in Japan with lifestyle westernization and aging. Deficiency of protein S, an important blood coagulation regulator, is a risk factor for VTE. Protein S deficiency prevalence in Asians is approximately 10 times that in Caucasians and that of protein S type II deficiency, associated with the protein S Tokushima mutation (K155E), is quite high in Japan. However, currently available methods for measuring protein S are not precise enough for detection of this deficiency. We developed a novel assay system for precise simultaneous determinations of total protein S activity and total protein S antigen level, using a general-purpose automated analyzer, allowing protein S-specific activity (ratio of total protein S activity to total protein S antigen level) to be calculated. Mean specific activity was 0.99 for samples from healthy individuals but 0.69 or less (mean-3SD) in protein S type II-deficient and warfarin-treated samples, but was 1.0 in an estrogen-treated sample with significantly decreased protein S antigen. Protein S gene analyses in healthy individuals with specific activity 0.69 or less revealed the K155E mutation in all three. These results show our new assay system to be an effective screening tool for protein S type II deficiency. This system can also be used in an automated analyzer, facilitating numerous sample measurements, and is, thus, applicable to regular medical checkups and diagnosing VTE. Such applications would potentially contribute to early detection of protein S type II deficiency, and, thereby, to thrombosis prevention.

Hereditary thrombophilia in Korean patients with idiopathic pulmonary embolism

PURPOSE

Hereditary thrombophilia (HT) is a major risk factor for idiopathic pulmonary embolism (iPE) and shows different prevalence among ethnic groups. The prevalence and clinical characteristics of HT in Korean patients with iPE were investigated.

MATERIALS AND METHODS

Patients with PE on computed tomography (CT) scan were recruited, and those with malignancy were excluded. Patients were divided into iPE and provoked PE (pPE) groups. The presence of HT in the iPE group was assessed by DNA sequencing of the corresponding gene in patients who had low levels of natural anticoagulants. The clinical characteristics of iPE with HT (iPE/HT+) were compared with those of iPE without HT (iPE/HT-) and pPE.

RESULTS

Out of 161 patients, 84 patients had iPE and 77 patients had pPE. Among 54 patients in the iPE group whose coagulation profiles were tested, 28 patients were diagnosed with HT (51.9%; 28/54). Compared with the iPE/HT- and pPE groups, the iPE/HT+ group showed the highest proportion of male patients (71.4%; p<0.001); the youngest mean age (44±14 years; p<0.001); and the highest frequencies for history of venous thromboembolism (64.3%; p<0.001), concurrent deep vein thrombosis (75.0%; p=0.021), and adverse clinical outcomes (42.9%, p<0.001). Protein C deficiency was the most common HT. On molecular genetic tests, causative mutation was identified in 13 patients.

CONCLUSION

In this study of Korean patients, about half of the patients with iPE had HT. Patients with iPE and HT were mostly young males with deep venous thrombosis (DVT), previous venous thromboembolism (VTE), and frequent adverse clinical outcomes. Therefore, Korean patients with iPE should be tested for HT.

A nation-wide analysis of venous thromboembolism in 497,180 cancer patients with the development and validation of a risk-stratification scoring system

The Asian population is thought to have a low risk of venous thromboembolism (VTE), but the epidemiology of VTE in cancer patients remains unclear. The National Health Insurance Research Database of Taiwan was used to find hospitalised patients newly-diagnosed with cancer to determine the incidence of VTE in cancer patients and to identify the risk factors for VTE. Between 1997 and 2005, 497,180 cancer patients were identified. During a median follow-up of 21.3 months (range 0-119.9 months), 5,296 patients developed VTE. The estimated incidence was 185 events per 100,000 person-years. Patients with a prior history of VTE and female patients between the ages of 40 and 80 carried high risk of VTE. The rate of VTE was relatively high in patients with myeloma, prostate cancer, lung cancer, gynaecologic cancers, sarcoma, and metastasis of unknown origin. We developed a risk-stratification scoring system to divide the cancer patients into four discrete risk groups (very low risk, low risk, intermediate, and high risk). The incidence of VTE in each group was 0.5%, 0.9%, 1.5%, and 8.7%, respectively (p < 0.001). This scoring system was validated in a separate patient cohort. In conclusion, VTE is a distinct burden for cancer patients in Taiwan. The risk scoring system could prove helpful in decision-making concerning thromboprophylaxis in cancer patients.

Thrombophilia among Chinese women with venous thromboembolism during pregnancy

AIMS

To assess the prevalence of thrombophilia among Chinese women with venous thromboembolism (VTE) developed during pregnancy.

METHODS

Based on information from a tertiary teaching unit, all recorded cases of deep vein thrombosis (DVT) and pulmonary embolism (PE) during pregnancy diagnosed between 1997 and 2005, were assessed for prevalence of thrombophilia. Fifty-five healthy women, who had at least one normal pregnancy but without any previous history of VTE, were recruited as controls.

RESULTS

A total of 44 subjects completed thrombophilia screening, of whom 5 (11%) were confirmed to have thrombophilia [protein C (PC) deficiency (2), protein S (PS) deficiency (1), combined PC & PS deficiency (1) and antithrombin III deficiency (1)]. Homozygous 5,10-methylenetetrahydrofolate reductase (C677T) gene mutation was found in 6 (14%) subjects but not in the controls. There was no antiphospholipid syndrome, activated PC resistance, factor V Leiden or prothrombin gene mutations.

CONCLUSION

In the Chinese population, PS and PC deficiencies are common thrombophilia for VTE during pregnancy and thrombophilia screening should be recommended in all pregnant women who suffer from VTE.

Epidemiology of Prothrombin G20210A Mutation in the Mediterranean Region

There are many genetic and acquired risk factors that are known to cause venous thromboembolic disorders (VTE). One of these is the Prothrombin G20210A mutation, which has been identified in 1996. Prothrombin G20210A mutation causes higher levels of the clotting factor prothrombin in the blood of carriers, which creates a higher tendency towards blood clotting (hypercoagulability), and therefore the carriers become at higher risk of developing VTE. High prevalence of Prothrombin G20210A mutation was reported in Caucasian populations, but the prevalence was almost absent in non-Caucasians. That was most obvious in countries of South Europe and the Mediterranean region. This review article discusses Prothrombin G20210A mutation, how it causes VTE, the origin of the mutation, and its distribution worldwide with special concentration on the Mediterranean area.

Racial differences in venous thromboembolism

The incidence of venous thrombosis (VTE) varies by race, with African-Americans having over 5-fold greater incidence than Asian-ancestry populations, and an intermediate risk for European and Hispanic populations. Known racial differences in genetic polymorphisms associated with thrombosis do not account for this gradient of risk, nor do known racial variations in environmental risk factors. Data on the incidence of and risk factors for VTE outside of Europe and North America and in non-European ancestry populations are sparse. Common genetic polymorphisms in European-Ancestry populations, such as factor V Leiden and prothrombin G20210A, and environmental risk factors, such as obesity, may account for some of the increased risk in European populations, and high factor VIII, high von Willebrand factor and low protein C levels and increased prevalence of obesity may explain some of the increased risk in African-Americans. The low rates in Asian populations may be partially explained by low clinical suspicion in a perceived low-risk population and lack of access to healthcare in other populations. As risk factors for thrombosis, such as surgery and treatment for cancer, are applicable to more people, as obesity increases in prevalence in the developing world, and as surveillance systems for VTE improve, VTE may increase in previously low-risk populations. While differences in VTE by race due to genetic predisposition will probably always be present, understanding the reasons for racial differences in VTE will help providers develop strategies to minimize VTE in all populations.

Normal ranges and genetic variants of antithrombin, protein C and protein S in the general Chinese population. Results of the Chinese Hemostasis Investigation on Natural Anticoagulants Study I Group

BACKGROUND

Inherited deficiency of antithrombin, protein C and protein S, three important, naturally occurring coagulation inhibitors, might play a major role in the occurrence of venous thromboembolism in Chinese. The establishment of age- and gender-related normal ranges of these inhibitors is crucial for an accurate diagnosis of these deficiencies.

DESIGN AND METHODS

We designed a prospective cross-sectional study recruiting healthy adults from four university-affiliated hospitals in China. Antithrombin, protein C and protein S were studied by measuring their activity. Gene analysis was performed when natural anticoagulant deficiency was suspected. Polymorphisms of the factor V gene were searched for among subjects who were positive for activated protein C resistance.

RESULTS

In 3493 healthy Chinese adults (1734 men, 1759 women; age 17-83 years), we found higher age-adjusted activities for protein C and protein S in men than in women but no sex difference for antithrombin. In women, mean protein C and protein S activities increased with age. In men, mean protein C levels increased with age up to the age of 49 but decreased after 50 years old; mean protein S levels decreased after 50 years of age. Antithrombin levels remained stable over time in women but decreased significantly after 50 years of age in men. Reference values according to age and sex allowed the identification of 15 genetic variants (protein C:10, antithrombin:3, protein S:2) in subjects with protein activity below the 1(st) percentile.

CONCLUSIONS

This is the largest survey ever conducted in the healthy general Chinese population. These normal ranges provide the essential basis for the diagnosis and treatment of thrombosis in Chinese.

Protein C and D-dimer are related to portal vein thrombosis in patients with liver cirrhosis

BACKGROUND AND AIM

To profile changes of coagulation, anticoagulation and fibrolytic factors associated with liver function failure and portal vein thrombosis (PVT) formation in chronic liver cirrhosis patients.

METHODS

A total of 116 cirrhotic patients admitted to our hospital from June 2006 to October 2008 were included in our study. All patients were classified into two groups: PVT group (31 patients), composed of patients with PVT and a control group (85 patients), including patients without PVT. Platelet, prothrombin time (PT), activated partial prothrombin time (APTT) and fibrinogen were measured. Also, plasma samples from the patients were analyzed for the levels of antithrombin III (AT-III), protein C (PC), protein S (PS), D-dimer, tissue-type plasminogen activator as well as plasminogen activator inhibitor-1. Statistical analyses were carried out to evaluate the correlation of specific variations with the disease status.

RESULTS

In general, the higher Child-Pugh scores, indicating the aggravation of hepatic impairment of the patients, correlated well with the prolonged PT/APTT and increased D-dimer, as well as decreased platelet, fibrinogen, PC and AT-III levels in the serum. Furthermore, we found that the PC, PS and D-dimer levels in PVT patients were 2.32 +/- 0.72 mg/L, 17.14 +/- 3.62 mg/L and 0.99 +/- 0.36 mg/L, respectively, both representing a significant difference compared with those in the control group without PVT. Logistic regression model shows that the odds ratio value of one unit of increase of PC and D-dimer were 0.48 and 15.57.

CONCLUSIONS

Cirrhotic patients displayed dysfunctions in the coagulation, anti-coagulation and fibrolytic systems. The development of PVT in these patients may be independently associated with the decrease of PC, PS and D-dimer. Furthermore, decreasing PC and increasing D-dimer may be risk factors inducing PVT in cirrhotic patients.

Low incidence of clinically apparent thromboembolism in Korean patients with multiple myeloma treated with thalidomide

The frequency of thromboembolic events (TE) in Caucasian patients with multiple myeloma (MM) receiving thalidomide as the initial treatment has been reported to be 10~58% without prophylactic anticoagulation. Korean MM patients treated with thalidomide were studied to determine the frequency of TE and associated risk factors. A retrospective medical record review of the Korean MM registry from 25 centers in Korea between 2003 and 2007 was performed. We assessed the incidence of arterial and venous TE and the associated clinical parameters. Three hundred and sixty MM patients (median age 61 years, range 32-88 years) received thalidomide treatment. Fourteen patients (3.9%) developed TE: 12 had venous and two had arterial locations. The sites for the venous TE included lungs (seven), lower extremities (four), upper extremities (one), and neck (one). Arterial TE developed in cerebral and peripheral arteries each. No single clinical parameter such as prerequisite for the metabolic syndrome, disease status, and treatment regimen were predictive for the development of TE. The frequency of TE in patients who received thalidomide as initial therapy (7/155) was not different from those who received thalidomide for progressive or relapsed disease (7/205, p = 0.592). The frequency of TE during thalidomide treatment in Korean patients with MM was low. No significant clinical factor was found to be a risk factor. The subgroup requiring thromboprophylaxis among the Korean patients with MM, receiving thalidomide, needs to be clarified.

Venous thromboembolism and ethnicity

Venous thromboembolism (VTE) has long been considered a disease that affects predominantly white populations, a misconception resulting from a paucity of epidemiological data from non-Western countries, and the low incidence of hereditary thrombophilia in those of non-Caucasian background. Over the last decade, interest has grown in this area with the emergence of evidence that VTE is as prevalent, if not more so, in the black population and is also common in Asian groups. Much is still to be learned, as our current knowledge of hereditary thrombophilia and acquired risk factors do not fully explain the risk of VTE in non-Caucasian groups. This review summarises the current understanding of ethnic variation in VTE and highlights the need for further research in this area.

Inherited thrombophilic factors do not increase central venous catheter blockage in children with malignancy

BACKGROUND

Central venous catheter (CVC) blockage is a common complication in pediatric oncology patients. We investigated whether inherited thrombophilic factors may predispose Chinese children with cancer to CVC blockage.

METHOD

Newly diagnosed patients with CVC inserted were recruited during a 30-month period and prospectively followed until CVC removal, end of treatment or death. Protein C (PC), protein S (PS), anti-thrombin III (AT-III), Factor V Leiden (FVL), prothrombin 20210 variant (p20210), and methylenetetrahydrofolate reductase (MTHFR) polymorphism (C677T), were studied with other acquired factors. The primary endpoint was CVC blockage and symptomatic thromboembolic events (TE) were recorded.

RESULT

Thirty-six patients were recruited. CVC blockage was found in 3/36 (8.3%) and the incidence was 0.23 per 1,000 catheter-days. Among the 3 with CVC blockage, 2 were heterozygous for MTHFR polymorphism and 1 was heterozygous for PC deficiency. One with ALL developed superior saggital sinus thrombosis while on asparaginase and he was heterozygous for MTHFR polymorphism. One ALL patient with combined heterozygous MTHFR polymorphism, PC and PS deficiency did not develop any CVC blockage during a median follow-up of 3.8 years. AT-III deficiency, FVL and p20210 were not found in all patients.

CONCLUSION

Compared to previous studies, our cohort had a much lower incidence of CVC blockage. A different pattern of inherited thrombophilic factors was found with heterozygous MTHFR polymorphism being the most common. We concluded that inherited thrombophilic factors alone were not associated with CVC blockage in our pediatric cancer patient population.

Risk factors of venous thromboembolism in thai patients

Venous thromboembolism (VTE) has been reported to be less common among Thais than Caucasians. Whether this observation reflects genetic or environmental factors, or both, is uncertain. To identify genetic and acquired risk factors of Thai patients with VTE, we enrolled in the study 105 consecutive Thai patients (34 men, 71 women) who had an objectively confirmed history of VTE. A complete clinical summary was obtained from each patient, with emphasis on personal and family history of VTE, as well as circumstantial vascular risk factors (surgery, immobilization, pregnancy, postpartum condition, trauma, oral contraceptive use, and malignancy). Of the 105 patients, 19% were found to have a malignancy. The mean age at the time of the first thrombotic episode was 52.1 years (range, 29-76 years), compared with 42.6 years (range, 17-82 years) for the patients without malignancy. Of the 85 patients without malignancy, 12.3% had protein S deficiency, 8.9% had protein C deficiency, 4.7% had antithrombin deficiency, 10.4% had antiphospholipid antibody, 30.4% had an elevated factor VIII level, 26.8% had an elevated factor XI level, 5.3% had hyperhomocysteinemia, and 16.5% were on oral contraceptives before the thrombotic episode. Factor V Leiden, the G20210A prothrombin gene mutation, and homozygosity for the C677T methylenetetrahydrofolate reductase (MTHFR) gene variant were not found. The VTE in 7.1% of the patients was considered to be secondary to recent surgery, trauma, and/or immobilization. Compared with studies of Caucasian patients, there were significant differences in the risk factors for VTE, with protein S deficiency and protein C deficiency being more common in the Thai patients. In contrast, factor V Leiden, the G20210A prothrombin gene mutation, and the C677T MTHFR gene mutation are not genetic risk factors among Thai patients with VTE. Malignancy and the use of oral contraceptives were the most common acquired risk factors for VTE in the Thai patients.

Venous thromboembolism in patients with pancreatic adenocarcinoma: lower incidence in Asian ethnicity

BACKGROUND

Pancreatic adenocarcinoma is one of the cancers most frequently associated with venous thromboembolism (VTE), with the varying incidences of 10%-20% reported in Western countries. Asians are known to have a lower risk for VTE than Caucasians, but few studies have been conducted regarding the incidence of VTE in Asian cancer patients.

MATERIALS AND METHODS

Incidence of radiologically confirmed VTE was assessed by review of medical records of all patients histologically diagnosed with advanced pancreatic adenocarcinoma, with follow-up conducted at a regional teaching hospital from Jun 2003 to Dec 2005.

RESULTS

Seventy five patients with advanced pancreatic adenocarcinoma were identified for evaluation (M:F=44:31, locally advanced:metastatic=25:50, median age:67 years). Four patients (5.3%) developed VTE during median follow-up period of 124 days. Three of four patients had metastatic disease and were receiving chemotherapy when VTE developed. The mean time from cancer diagnosis to the detection of VTE was 160 days. No episodes of peripheral arterial thrombosis were detected, but three multiple cerebral infarctions occurred, which proved fatal in all three. Median survival time was shorter in patients with VTE than those without, but the difference was not statistically significant (4.3 vs 6.6 months).

CONCLUSION

The incidence of VTE complications in Korean patients with advanced pancreatic cancer was 5.3%, which is lower than that observed in other ethnic groups. Our study warrants further prospective investigations on the incidence and mechanism of VTE and cerebral infarctions in cancer patients of different ethnic groups.

Thrombosis and bleeding disorders outside Western countries

The rapidly developing countries of Asia are witnessing substantial progress in the awareness of bleeding and thrombotic disorders as important health care problems. It has been thought for a long time that venous thromboembolism is very rare in Asia. Recent large studies that involved the majority of Asian countries demonstrated that this is not true, so that the practice of not using thromboprophylaxis in high-risk medical and surgical cases should be abandoned. The management of hemophilia and allied coagulation disorders has also dramatically improved in several Asian countries, due to the increased availability of blood products for replacement therapy coupled with the leadership role exerted by a few charismatic physicians, particularly in India and Thailand. As to the future, countries such as China and India have the capacity and expertise in biotechnology to consider the production of recombinant factors and gene transfer as the best strategies to tackle the management of persons with hemophilia in these densely populated and huge countries.

Inherited risk factors for deep venous thrombosis following total hip arthroplasty in Japanese patients: matched control study

BACKGROUND

Inherited predisposing risk factors for deep venous thrombosis (DVT) have been clearly identified in Caucasians, but there are fewer reports evaluating these factors in the Japanese. This study was undertaken to assess the predisposing risk factors for DVT following elective total hip arthroplasty (THA) in Japanese patients.

METHODS

We studied 60 patients who underwent THA. The study group consisted of 30 patients who developed DVT diagnosed by duplex sonography examination; the 30 patients who did not develop DVT served as a control group. They were matched in age, sex distribution, diagnosis (osteoarthritis secondary to dysplastic hip), and operation side(s) (bilateral or unilateral). Protein C, protein S, antithrombin III, and plasminogen activities and the plasma homocysteine level were measured. Three polymorphisms were screened for the factor V Leiden polymorphism, the factor II G20210A polymorphism, and the methylene tetrahydrofolate reductase C677T polymorphism.

RESULTS

Plasma protein C activity was 82.39% +/- 14.24% in the DVT patients and 88.76% +/- 23.27% in the controls. Plasma protein C activity was significantly reduced in the study group, whereas other serologic and genetic analyses revealed no significant differences.

CONCLUSIONS

Three genetic risk factors established in Caucasian patients are not valuable for evaluating DVT risk in Japanese patients. Reduced protein C activity may be a risk factor for DVT after THA.

Effect of phosphatidylcholine, phosphatidylethanolamine and lysophosphatidylcholine on the protein C/protein S anticoagulation system

Phosphatidylserine is known to significantly accelerate the blood coagulation reaction. In a previous communication submitted for publication, we demonstrated that phosphatidylcholine, phosphatidylethanolamine and lysophosphatidylcholine showed effects on the blood coagulation reaction using the factor Xa-prothrombin reaction system, and discuss a new function of membrane phospholipids. The present study examined the role of phospholipids in the blood coagulation regulatory reaction (anticoagulation system), by studying the effects of phospholipids on the protein C/protein S reaction. We have established quantitative methods for measuring activated protein C activity and protein S activity, and used them to measure their activity after the addition of liposomes with different phospholipid compositions. We found that phosphatidylcholine inhibited activated protein C and protein S activities in a dose-dependent manner, as in the factor Xa-prothrombin reaction system. On the other hand, phosphatidylethanolamine and lysophosphatidylcholine showed no effect on activated protein C activity. Phosphatidylethanolamine inhibited and lysophosphatidylcholine accelerated coagulation activity in the factor Xa-prothrombin system, but such effects were not observed in the protein C/protein S reaction system. The coagulation and anticoagulation reactions are exquisitely balanced by thrombin, with a role both as a procoagulant and anticoagulant. Therefore, it is understandable that phosphatidylethanolamine and lysophosphatidylcholine show different effects in the factor Xa-prothrombin and protein C/protein S reaction systems. It appears that coagulation and anticoagulation reactions are co-ordinated and controlled by changes in phospholipid composition of the cellular membrane where the coagulation reaction takes place.

Protein S and protein C gene mutations in Japanese deep vein thrombosis patients

OBJECTIVES

Coagulation factor V Leiden has not been detected in Japanese patients suffering from thrombosis. Hitherto, the constitutional background of Japanese thrombotic patients has never been systematically examined. We have performed a systematic investigation to determine pathogenesis for deep vein thrombosis in a Japanese population.

DESIGN AND METHODS

Routine coagulation and fibrinolysis tests were performed to determine the activities of protein S, protein C, antithrombin, plasminogen and fibrinogen. Gene analysis was performed in thrombotic patients having low activities of these factors.

RESULTS

Our study indicates that the frequency (19/85 = 0.22) of mutations of protein S gene in the Japanese patients was 5-10 times higher than that of mutations of protein S gene in Caucasian patients, and the frequency (8/85 = 0.09) of mutations of protein C gene was almost three times higher than that of Caucasian patients. The frequency of antithrombin gene mutation was similar in both populations.

CONCLUSION

Our study reinforces that the genetic anomaly in the protein S/protein C anticoagulation system is an important risk factor for thrombophilia in the Japanese population.

Racial disparities in risk factors for thrombosis

PURPOSE OF REVIEW

Until recently, the paucity of characterization of the epidemiology of venous thromboembolism among non-Caucasians has contributed to the misconception that race or ethnicity does not modify disease presentation. This review will describe the previously poorly documented magnitude of venous thromboembolism disease burden among four racial cohorts, by defining disease incidence and associated morbidity/mortality from available literature data.

RECENT FINDINGS

Emerging data suggest that African-Americans possess the highest burden of venous thromboembolism, and Asians the lowest, compared with the Caucasian population. In both racial groups, however, the inheritable thrombophilic risk factors prevalent in Caucasians (factor V Leiden, Prothrombin G20210A) are distinctly rare. The presence of yet undetermined modifiers of disease, conferring susceptibility or resistance to venous thromboembolism among these racial groups, is suspected and requires further investigation.

SUMMARY

Racial disparity in thrombotic disorders exists in the divergent patterns of disease incidence among different racial/ethnic cohorts, yet the genetic determinants of disease and modifiers of risk remain obscure. Further research focused on delineating the underlying etiologies of venous thromboembolism across different racial/ethnic groups promises to be a productive and much needed area of exploration.

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.