Prothrombin G20210A gene mutation and further prothrombotic risk factors in childhood thrombophilia

Incidence of VTE in asymptomatic children with deficiencies of antithrombin, protein C, and protein S: a prospective cohort study

Although antithrombin, protein C, and protein S defects are well-recognized inherited risk factors for venous thromboembolism (VTE) in adults, whether they predispose children to these vascular disorders as well is undefined. In a prospective cohort study, we assessed the incidence of spontaneous and risk period-related VTE in children who were family members of adults who, after an episode of symptomatic VTE, had then been identified as carriers of these abnormalities. A total of 134 children from 87 families were enrolled. Seventy (51.5%) of these children were carriers of an inherited defect, and the remaining 64 were not; the mean observation period was 4 years (range, 1-16 years) and 3.9 years (range, 1-13), respectively. Sixteen risk periods were experienced by carriers, and 9 by noncarriers. Six VTE occurred in the 70 carriers during 287 observation-years, accounting for an annual incidence of 2.09% patient-years (95% confidence interval, 0.8-4.5), compared with none in the 64 noncarriers during 248 observation-years. Of the 14 children with thrombophilia who experienced a risk period for thrombosis, 4 (28.6%) developed a VTE episode. The overall incidence of risk-related VTE was 25% per risk period (95% confidence interval, 6.8-64). In conclusion, the thrombotic risk in otherwise healthy children with severe inherited thrombophilia does not seem to differ from that reported for adults with the same defects. Screening for thrombophilia in children who belong to families with these defects seems justified to identify those who may benefit from thromboprophylaxis during risk periods for thrombosis.

Prevalence of the prothrombin G20210A mutation among ischemic stroke patients

Introduction: Ischemic stroke is characterized as a sudden neurological deficit attributed to an acute focal injury of the central nervous system by a vascular cause. This study was performed to determine the frequency of G20210A mutation in the prothrombin gene and its effectiveness on the incidence of ischemic stroke in the Erbil city of Kurdistan region, Iraq. Methods: A total of 50 patients with ischemic stroke was analyzed for the detection of prothrombin gene mutation (G20210A), using polymerase chain reaction (PCR), Restriction fragment length polymorphism (RFLP) with Hind III restriction enzyme. Results: We observed no evidence of an association between ischemic stroke and G20210A mutation in the prothrombin gene in this region. Conclusion: Our finding demonstrates that prothrombotic gene variant seems not to be linked to the incidence of ischemic stroke in Erbil region.

Economic evaluation of a novel genetic screening test for risk of venous thromboembolism compared with standard of care in women considering combined hormonal contraception in Switzerland

AIM

The aim of this study was to assess the cost effectiveness of the Pill Protect (PP) genetic screening test for venous thromboembolism (VTE) risk compared with standard of care (SoC), for women considering combined hormonal contraceptives (CHCs) in Switzerland.

METHODS

A two-part microsimulation model was developed to estimate VTE events, costs and quality-adjusted life years (QALYs) associated with the PP and SoC strategies. In the first portion of the model, a cohort of 1 million Swiss first-time seekers of a CHC were simulated. It was determined whether each women would receive a CHC or non-CHC by using prescribing patterns elicited from a modified Delphi study. These results formed the basis of the SoC strategy. For the PP strategy, a PP test was included and the results considered in addition to SoC practice. Each woman then entered a Markov model that captured morbidity and mortality over a lifetime. The risk of having a VTE was derived from the risk algorithm that underpins the PP test. The remaining model inputs relating to population characteristics, costs, health resource use, mortality and utilities were derived from published studies or national sources. The model was validated and calibrated to align with population-based studies. Extensive uncertainty analyses were conducted.

RESULTS

From a Swiss health system perspective, the PP strategy in comparison with the SoC strategy generated an additional CHF 231, and gained 0.003 QALYs per woman, leading to an incremental cost-effectiveness ratio of CHF 76 610 per QALY gained. Assuming a threshold of CHF 100 000 per QALY gained, the PP strategy is likely to be cost effective. Our results were generally robust to variations in the parameter values.

CONCLUSIONS

The PP test may be cost effective in Switzerland for screening women seeking CHCs for their risk of VTE based on the current evidence.

Post thrombotic syndrome following deep vein thrombosis in paediatric patients

Background Although well characterised in adults, less is known about post-thrombotic syndrome in children. In this review, current knowledge regarding paediatric post-thrombotic syndrome is summarised, with particular emphasis on pathophysiology, aetiology, diagnosis and management. Methods A Medline literature review was performed using search terms 'post thrombotic syndrome', 'post phlebitic syndrome', paediatric and children. Relevant articles were identified and included for summation analysis. Results The incident of paediatric venous thromboembolism is rising. Deep vein thrombosis can cause venous hypertension through a combination of venous reflux, venous obstruction and impairment of the calf muscle pump, leading to development of post-thrombotic syndrome. In children, this is more likely to occur if deep vein thrombosis diagnosis and treatment are delayed, if a higher number of vessels are involved, and if factors such as D-dimer are elevated at diagnosis and throughout treatment. Post-thrombotic syndrome occurs in about 26% of paediatric deep vein thrombosis, though the results of individual studies vary widely. A number of tools exist to diagnose paediatric post-thrombotic syndrome, including the modified Villalta scale and Manco-Johnson instrument. Once post-thrombotic syndrome develops, the mainstay of treatment remains supportive, with little evidence of benefit from pharmacological measures. Conclusion Surgical or interventional treatment is not advised except in exceptional cirumstances, due to variable prognosis of PTS in paediatric populations with rising incidence of paediatric venous thromboembolism, it follows that the prevalence of post-thrombotic syndrome in children may also increase. Evidence-based venous thromboembolism prevention strategies need to be implemented for prevention of deep vein thrombosis, but when it does occur, deep vein thrombosis requires prompt and effective treatment to prevent post-thrombotic syndrome. Optimum treatment strategies for post-thrombotic syndrome require further investigation.

Impact of Thrombophilia on the Risk of Hypoxic-Ischemic Encephalopathy in Term Neonates

BACKGROUND

The incidence of neonatal hypoxic-ischemic encephalopathy (HIE) is reportedly high in countries with limited resources. Its pathogenesis is multifactorial. A role for thrombophilia has been described in different patterns of preterm and full-term perinatal brain injury.

AIM

This study aims to identify risk factors associated with neonatal HIE and also to determine the contributions of genetic thrombophilia in the development of neonatal HIE.

METHODS

Sixty-seven neonates with HIE and 67 controls were enrolled in the study. Clinical history and examination were undertaken. Patients and controls were tested for the presence of factor V G1691A and prothrombin G20210A mutations. In addition, protein S, protein C, and antithrombin III levels were assessed.

RESULTS

Parental consanguinity and performing emergency cesarean section (CS) were significant risk factors for neonatal HIE (odds ratio [OR] 6.5, 95% confidence interval [CI] 2.6-15.3, P < .001, OR 12.6, 95% CI 2.52-63.3, P = .002, respectively). No significant difference was found regarding maternal age and parity. About 33% of cases and 6% of controls were found to have at least 1 thrombophilic factor ( P < .001). Factor V G1691A mutation significantly increased the risk of neonatal HIE (OR 4.5, 95% CI 1.4-14.5, P = .012), while prothrombin G 20210A mutation and protein C deficiency were not.

CONCLUSION

Parental consanguinity, emergency CS, and factor V mutation may contribute to the higher risk of developing neonatal HIE.

Inherited thrombophilia in children

Thrombosis in children has multiple etiologies, including inherited disorders such as factor V Leiden mutation, prothrombin 20210A mutation, and deficiencies in protein C, S, or antithrombin. Epidemiology of the disorders varies, as does the risk of thrombosis. Venous thromboembolism is the typical presentation. However, more severe anticoagulant protein deficiencies may present with purpura fulminans. Treatment of thrombosis is relatively uniform, regardless of the underlying genetic risk factor. In this article, we discuss the most well-studied inherited thrombophilias and the epidemiology, pathophysiology, and relative thrombotic risk of each. Treatment of thrombosis is also briefly reviewed.

Risk of venous thromboembolism associated with single and combined effects of Factor V Leiden, Prothrombin 20210A and Methylenetethraydrofolate reductase C677T: a meta-analysis involving over 11,000 cases and 21,000 controls

Genetic and environmental factors interact in determining the risk of venous thromboembolism (VTE). The risk associated with the polymorphic variants G1691A of factor V (Factor V Leiden, FVL), G20210A of prothrombin (PT20210A) and C677T of methylentetrahydrofolate reductase (C677T MTHFR) genes has been investigated in many studies. We performed a pooled analysis of case-control and cohort studies investigating in adults the association between each variant and VTE, published on Pubmed, Embase or Google through January 2010. Authors of eligible papers, were invited to provide all available individual data for the pooling. The Odds Ratio (OR) for first VTE associated with each variant, individually and combined with the others, were calculated with a random effect model, in heterozygotes and homozygotes (dominant model for FVL and PT20210A; recessive for C677T MTHFR). We analysed 31 databases, including 11,239 cases and 21,521 controls. No significant association with VTE was found for homozygous C677T MTHFR (OR: 1.38; 95 % confidence intervals [CI]: 0.98-1.93), whereas the risk was increased in carriers of either heterozygous FVL or PT20210 (OR = 4.22; 95 % CI: 3.35-5.32; and OR = 2.79;95 % CI: 2.25-3.46, respectively), in double heterozygotes (OR = 3.42; 95 %CI 1.64-7.13), and in homozygous FVL or PT20210A (OR = 11.45; 95 %CI: 6.79-19.29; and OR: 6.74 (CI 95 % 2.19-20.72), respectively). The stratified analyses showed a stronger effect of FVL on individuals ≤ 45 years (p value for interaction = 0.036) and of PT20210A in women using oral contraceptives (p-value for interaction = 0.045). In this large pooled analysis, inclusive of large studies like MEGA, no effect was found for C677T MTHFR on VTE; FVL and PT20210A were confirmed to be moderate risk factors. Notably, double carriers of the two genetic variants produced an impact on VTE risk significantly increased but weaker than previously thought.

Venous thromboembolism in the paediatric patient

Venous thromboembolism is a concern in the paediatric population and its incidence seems to be increasing. Symptoms and signs may be subtle so a high degree of suspicion is needed. Paediatric patients represent a unique challenge in the provision of anticoagulation due to their unique physiology.

Venous thrombosis in children: an emerging issue

More and more cases of venous thrombosis are diagnosed in children thanks to newer imaging modalities. Central venous catheters have become commonplace in the care of critically ill children and have contributed to the increased rate of thrombotic events. Lastly, children who develop life-threatening or chronic medical conditions are surviving longer because of advanced medical therapies; these intensive therapies can be complicated by events such as thrombosis. Over the last 10 years, specific guidelines for treating thrombosis in children have become available. Nevertheless, in many situations anticoagulant treatment is specially tailored to each individual patient's needs. Some new antithrombotic drugs which have undergone clinical testing in adults might be beneficial to paediatric patients with thromboembolic disorders; unfortunately, clinical data and reports on the use of these drugs in children, when available, are extremely limited. The aim of this review is to provide physicians with enough background information to be able to manage thrombosis in children. First, by helping them detect a thrombotic event in a child. Upon confirmation of the diagnosis, the physician will request the appropriate tests and will choose the best treatment on the basis of the guidelines and recommendations. Moreover, the paediatrician will have the information he or she needs to identify which children are at highest risk of acute thrombotic events and relevant long-term sequelae and, therefore, to decide on the appropriate prophylactic or pharmacologic strategy. Lastly, we would like to provide the paediatrician with information on future drugs with regard to the treatment and prophylaxis of thrombosis.

Thrombophilia testing in neonates and infants with thrombosis

In neonates and infants with idiopathic venous thrombosis (VTE) and in pediatric populations in which thromboses were associated with medical diseases, inherited thrombophilia (IT) have been described as risk factors. Follow-up data for VTE recurrence in neonates suggest a recurrence rate between 3% in provoked and 21% in idiopathic VTE. Apart from underlying medical conditions, recently reported systematic reviews on pediatric VTE have shown significant associations between factor V G1691A, factor II G20210A, and deficiencies of protein C, protein S and antithrombin, even more pronounced when combined IT were involved. Independent from the age at first VTE onset, the pooled odds ratios (OR: single IT) for VTE ranged from 2.4 for the factor II G20210A mutation to 9.4 in neonates and infants with antithrombin deficiency. The pooled OR for persistent antiphospholipid antibodies/lupus anticoagulants was 4.9 for pediatric patients with venous VTE. The factor II G20210A mutation (OR: 2.1), and deficiencies of protein C (OR: 2.4), S (OR: 3.1) and antithrombin (OR: 3.0) also played a significant role at recurrence. Based on these data, screening and treatment algorithms must be discussed.

Pediatric venous and arterial noncerebral thromboembolism in Denmark: a nationwide population-based study

OBJECTIVE

To assess the incidence rate (IR), changes in IR over time, risk factors, treatment, and outcomes of pediatric noncerebral thromboembolism (TE).

STUDY DESIGN

The study included all patients aged 0 to 18 years diagnosed with first-ever noncerebral venous thromboembolism (VTE) and/or arterial TE in Denmark between 1994 and 2006. Patients were identified in national registries, followed by validation of diagnoses by medical records review.

RESULTS

We confirmed 331 cases of VTE and 46 cases of arterial TE during 15.8 million person-years of observation, with corresponding IRs of 2.09 and 0.29 per 100 000 person-years. The IR peaked in infancy (age <1 year) for both VTE and arterial TE, with an additional peak among adolescents (age 15 to 18 years) for VTE. Boys predominated in IR of VTE in infancy, whereas girls did so in adolescence (P < .01). The IRs of VTE and arterial TE remained stable during the study period, but with an trend toward increasing VTE in 2001 to 2006 (P = .064). Underlying diseases/external triggers were present in 86.6% of the patients, and thrombophilia was present in 47.9% of the VTE cases. All-cause and TE-related 30-day case fatalities were 4.0% and 1.6%, respectively.

CONCLUSIONS

We found age- and sex-related disparities in the IRs of pediatric VTE and arterial TE, but insignificant changes in IR from 1994 to 2006.

Polymorphism analysis of MTHFR, factor II, and factor V genes in the Pomeranian population of Espirito Santo, Brazil

Pomeranian populations worldwide immigrated originally from the north of Europe, and because of their preferential marriage, religion, and cultural habits, they show little or no reproductive mixing with local populations. Methylenetetrahydrofolate reductase gene (MTHFR) C677T, Factor V Leiden, and Factor II G20210A polymorphisms are linked to augmented clotting and their frequencies may vary according to population ethnicity. We aimed to assess the frequencies of these thrombophilic alleles in the Pomeranian population residing in Espirito Santo and compare with the general population of the Espirito Santo state, Brazil. A total of 200 individuals were analyzed. The intrapopulation fixation index of the MTHFR C677T polymorphism was 0.03736. The observed heterozygosity was 0.44 and 0.4 for the general and Pomeranian populations, respectively. According to the chi-square test, both populations are in Hardy-Weinberg equilibrium. Four polymorphic alleles were detected for Factor II (2.02%) and 8 for Factor V (4.81%). Our results show that there is gene flow between the general and the Pomeranian population of Espirito Santo, which should no longer be considered an isolated population.

The origin of Eastern European Jews revealed by autosomal, sex chromosomal and mtDNA polymorphisms

Background

This study aims to establish the likely origin of EEJ (Eastern European Jews) by genetic distance analysis of autosomal markers and haplogroups on the X and Y chromosomes and mtDNA.

Results

According to the autosomal polymorphisms the investigated Jewish populations do not share a common origin, and EEJ are closer to Italians in particular and to Europeans in general than to the other Jewish populations. The similarity of EEJ to Italians and Europeans is also supported by the X chromosomal haplogroups. In contrast according to the Y-chromosomal haplogroups EEJ are closest to the non-Jewish populations of the Eastern Mediterranean. MtDNA shows a mixed pattern, but overall EEJ are more distant from most populations and hold a marginal rather than a central position. The autosomal genetic distance matrix has a very high correlation (0.789) with geography, whereas the X-chromosomal, Y-chromosomal and mtDNA matrices have a lower correlation (0.540, 0.395 and 0.641 respectively).

Conclusions

The close genetic resemblance to Italians accords with the historical presumption that Ashkenazi Jews started their migrations across Europe in Italy and with historical evidence that conversion to Judaism was common in ancient Rome. The reasons for the discrepancy between the biparental markers and the uniparental markers are discussed.

Reviewers

This article was reviewed by Damian Labuda (nominated by Jerzy Jurka), Kateryna Makova and Qasim Ayub (nominated by Dan Graur).

Screening for deep venous thrombosis after idiopathic scoliosis surgery in children: a pilot study

BACKGROUND

Venous thrombosis remains an uncommon disorder in childhood. However, the incidence appears to be increasing for a multitude of reasons. The aim of the study was to detect asymptomatic deep venous thrombosis and prothrombotic diseases in nonsyndromic children undergoing scoliosis surgery.

METHODS

A prospective study including forty successive teenagers scheduled for posterior spinal fusion. Patients with scoliosis with a history of hemoglobinopathies, cardiac defects, blood clots, early onset osteoporosis, as well as patients with skeletal dysplasias and nonskeletal dysplastic syndromic entities have been excluded. The protocol was designed for active screening of deep venous thrombosis using color Doppler ultrasonography on a day before surgery and repeated on the 3rd, 7th and 15th day postoperatively. Evaluation of prothrombotic disorders included antithrombin and protein C activities, and total protein S antigen level.

RESULTS

No patient has manifested clinical symptoms of venous thrombosis in our study. Preoperative Doppler and ultrasound examinations were normal in all patients. Although repeated Doppler ultrasonography demonstrated a transient small clot in two patients. Congenital antithrombin deficiency of 5% has been observed in one child only, without the development of deep venous thrombosis.

CONCLUSION

Thromboembolic event seems to be rare after scoliosis surgery. Prophylaxis for venous thrombosis should not be recommended in such patient. But, larger series are required to confirm such results.

The evaluation and management of postnatal thromboses

In the pediatric population, neonates have the highest risk for thromboembolism (TE), most likely due to the frequent use of intravascular catheters. This increased risk is attributed to multiple risk factors. Randomized clinical trials dealing with management of postnatal thromboses do not exist, thus, opinions differ regarding optimal diagnostic and therapeutic interventions. This review begins with an actual case study illustrating the complexity and severity of these types of cases, and then evaluates the neonatal hemostatic system with discussion of the common sites of postnatal thrombosis, perinatal and prothrombotic risk factors, and potential treatment options. A proposed step-wise evaluation of neonates with symptomatic postnatal thromboses will be suggested, as well as future research and registry directions. Owing to the complexity of ischemic perinatal stroke, this topic will not be reviewed.

Fibrinogen alpha and gamma genes and factor VLeiden in children with thromboembolism: results from 2 family-based association studies

Previous case-control studies showed that genetic variation in the fibrinogen gamma gene (FGG) increased the risk for deep vein thrombosis (VT) in adults. We investigated the association between the fibrinogen alpha (FGA) and FGG haplotypes, the factor V(Leiden)-mutation, and pediatric VT and thromboembolic stroke (TS) in 2 independent study samples. Association analysis revealed that the FGA-H1 and FGG-H2 haplotypes were significantly overtransmitted to VT patients (FGA-H1, P = .05; FGG: H2, P = .032). In contrast, the FGG-H3 haplotype was undertransmitted (P = .022). In an independent study sample, FGA-H1 (P = .008) and FGG-H2 (P = .05) were significantly associated with TS. The association of FGA and FGG haplotypes with VT was more pronounced in FV(Leiden)-negative families (FGA-H1, P = .001; FGG-H2, P = .001), indicating a genetic interaction between both risk factors. The risk-conferring FGG-H2 and the protective FGG-H3 haplotypes correlated with low (FGG-H2) and high (FGG-H3) levels of the gamma' chain variant, respectively. These results provide independent and novel evidence that FGA-H1 and FGG-H2 variants are associated with an increased risk of VT and TS in children. The observed negative correlation of genetic VT risk with the plasma levels of the fibrinogen gamma' variant suggests that FGG-H2 and -H3 haplotypes modify thrombosis risk by controlling the level of this FGG splice isoform.

Association of the protein Z ATG haplotype with symptomatic nonvascular stroke or thromboembolism in white children: a family-based cohort study

To clarify the role of protein Z (PZ) in children with stroke/thromboembolism (TE), the present haplotype (HT)–based family study was performed. We genotyped 365 pediatric stroke/TE families (stroke n = 216; TE n = 149) for 4 single nucleotide polymorphisms (SNPs; rs3024718, rs3024731, rs3024772, and rs3024778) to assess the association between genetic variation within a conserved block of linkage disequilibrium harboring the PZ gene and pediatric TE. Association was assessed with use of the transmission disequilibrium test (TDT), corrected for multiple testing (permutation testing: HAPLOVIEW). In addition, PZ antigen was determined and correlated with carriership of PZ haplotypes and the FV G1691A mutation. Rs3024718, rs3024731, and rs3024772 are in tight linkage disequilibrium (LD) and define 4 haplotypes, capturing 97% of the genetic variation for this LD block. HT1 (ATG) was significantly overtransmitted from parents to affected offspring (HT frequency 73.5%, T:U 122:80, χ2 = 8.791, P = .003). The ATG risk haplotype was significantly correlated with greater PZ antigen levels. Multivariate analysis adjusted for age, sex, established thrombophilias, smoking, fibrinogen, and PZ levels revealed a significant association of the ATG haplotype and TE in children (odds ratio [OR] 1.4; 95% confidence interval [95% CI] 1.08-1.93). Our results suggest that the ATG haplotype of the PZ gene is a genetic marker for symptomatic TE in white German children.

The evaluation and management of neonatal coagulation disorders

Neonatal hemostatic abnormalities can present diagnostic and therapeutic challenges to the physician. Developmental deficiencies and/or increases of certain coagulation proteins, coupled with acquired or genetic risk factors, can result in a hemorrhagic or thromboembolic emergency. The timely diagnosis of a congenital hemorrhagic or thrombotic disorder can avoid significant long-term sequelae. However, due to the lack of randomized clinical trials addressing the management of neonatal coagulation disorders, treatment strategies are usually empiric and not evidence-based. In this chapter, we will review the neonatal hemostatic system and will discuss the most common types of hemorrhagic and thrombotic disorders. Congenital and acquired risk factors for hemorrhagic and thromboembolic disorders will be presented, as well as current treatment options. Finally, suggested evaluations for neonates with either hemorrhagic or thromboembolic problems will be reviewed.

Influence of the factor II G20210A variant or the factor V G1691A mutation on symptomatic recurrent venous thromboembolism in children: an international multicenter cohort study

OBJECTIVE

To determine the relative importance of the factor (F) II G20210A or FV G1691A mutations as risk factors or predictors for fatal/non-fatal recurrent venous thromboembolism (VTE) in children.

METHODS

In the present cohort, the rate of VTE recurrence and the time to recurrence in relation to FII, FV, age, and sex was determined in consecutively enrolled patients with VTE aged newborn to

RESULTS

Of the 416 children enrolled, 44 had recurrent VTE at a median of 12 months following VTE onset. The overall incidence rate of recurrence was 19.8, 57.9 in patients with the FII variant, 17.9 for FV carriers, and 11.8 in the control cohort. When comparing FII patients, FV children and the control cohort multivariate analysis (Cox regression) adjusted for age and sex showed that the FII variant (hazard ratio 2.6; 95% confidence interval 1.1-5.9) influenced the hazard for recurrent VTE.

CONCLUSIONS

Based on multivariate analysis, the presence of the FII variant was associated with an increased risk of VTE recurrence.

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Key Words Collapse

MESH Headings

• Adolescent
• Age Factors
• Child
• Child, Preschool
• Cohort Studies
• Factor V/genetics
• Female
• Global Health
• Humans
• Infant
• Infant, Newborn
• Male
• Point Mutation
• Polymorphism, Single Nucleotide
• Prothrombin/genetics
• Recurrence
• Sex Factors
• Venous Thromboembolism/genetics

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Grants Collapse

Affiliation(s)

G Young Division of Hematology/Oncology, Children's Hospital Los Angeles, Los Angeles, CA, USA
S Becker
C Düring
F Friedrichs
N Goldenberg
G Kenet
M Manco-Johnson
C Scheffold
U Nowak-Göttl

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Incidence of and risk factors for childhood thrombosis: a single-center experience in Ankara, Turkey

This study was conducted to analyze the incidence of and risk for thrombosis in thrombotic children monitored in the Department of Pediatric Hematology of our hospital at the time of diagnosis, in addition to the clinical characteristics of those patients. The clinical and laboratory findings of 122 patients diagnosed with thrombosis from 1997 to 2006 were retrospectively analyzed. The incidence of thrombosis was 88.6/10,000 hospital admissions. The authors found that 31.1% of the patients studied had a thrombosis in more than 1 region. The incidence of thrombosis by anatomic site was as follows: 42 thromboses in the peripheral arterial system, 39 in an intracardiac region, 38 in the abdominal venous system, 36 in the deep peripheral venous system, and 28 in the cerebral vascular system. The mean age of the patients at the time of diagnosis was 4.9 years. Of the patients studied, 10.7% were neonates, 35.3% were infants younger than 1 year, and 48.4% were younger than 2 years. Most of the patients had a congenital cardiac disease and spontaneous thrombosis, and 66.1% had at least 1 acquired risk factor, the most common of which were having undergone surgery (42%) or wearing a central venous catheter (39%). A hereditary factor for the development of thrombosis was present in 54% of the patients. The most frequently observed hereditary risk factor was the MTHFR 677C-T mutation, and the second most common was the factor V Leiden mutation. Thrombosis should be considered a systemic disorder, and thrombotic patients should be evaluated with appropriate methods. Acquired and hereditary risk factors should be analyzed systematically in thrombotic patients.

Inherited Thrombophilia

Inherited thrombophilia can be defined as a genetically determined predisposition to the development of thromboembolic complications. Since the discovery of activated protein C resistance in 1993, several additional disorders have been described and, at present, it is possible to identify an inherited predisposition in about 60 to 70% of patients with such complications. These inherited prothrombotic risk factors include qualitative or quantitative defects of coagulation factor inhibitors, increased levels or function of coagulation factors, defects of the fibrinolytic system, altered platelet function, and hyperhomocysteinemia. In this review, the main inherited prothrombotic risk factors are analyzed from epidemiological, laboratory, clinical, and therapeutic points of view. Finally, we discuss the synergism between genetic and acquired prothrombotic risk factors in particular conditions such as childhood and pregnancy.

Genetics of hemostasis: differential effects of heritability and household components influencing lipid concentrations and clotting factor levels in 282 pediatric stroke families

BACKGROUND

The identification of heritable and environmental factors possibly influencing a condition at risk should be a prerequisite for the search for the proportion of variance attributable for shared environmental effects (c(2)) modulating the risk of disease. Such epidemiologic approaches in families with a first acute ischemic stroke during early childhood are lacking.

OBJECTIVES

Our goal was to estimate the phenotypic variation within lipid concentrations and coagulation factor levels and to estimate the proportions attributable to heritability (h(2)r) and c(2) in pediatric stroke families.

METHODS

Blood samples were collected from 1,002 individuals from 282 white stroke pedigrees. We estimated h(2)r and c(2) for lipoprotein (a) [Lp(a)], cholesterol, high-density lipoprotein, low-density lipoprotein (LDL), fibrinogen, factor (F) II, FV, FVIIIC, von Willebrand factor (vWF), antithrombin, protein C, protein S, plasminogen, protein Z, total tissue factor pathway inhibitor (TFPI), prothrombin fragment F1.2, and D-dimer, using the variance component method in sequential oligogenetic linkage analysis routines.

RESULTS

When incorporating h(2)r and c(2) in one model adjusted for age, blood group, sex, smoking, and hormonal contraceptives, significant h(2)r estimates were found for Lp(a), LDL, fibrinogen, protein C, and protein Z. In addition to the significant h(2)r estimates, c(2) showed a significant effect on phenotypic variation for fibrinogen, protein C, and protein Z. A significant c(2) effect was found for cholesterol, and plasma levels of FII, FV, vWF, antithrombin, protein S, plasminogen, and TFPI, ranging from 9.3% to 33.2%.

CONCLUSIONS

Our research stresses the importance of research on the genetic variability and lifestyle modifications of risk factors associated with pediatric stroke.

Incidence of deep vein thrombosis related to peripherally inserted central catheters in children and adolescents

BACKGROUND

Peripherally inserted central catheters (PICC) in children and adolescents are being used with increasing frequency. We sought to determine the incidence and characterize risk factors of deep vein thrombosis associated with peripherally inserted central catheters in a pediatric population.

METHODS

We conducted a prospective study involving consecutive patients referred to the radiology department of a tertiary care university-affiliated hospital for insertion of a peripherally inserted central catheter. We included patients aged 18 years or less who weighed more than 2.5 kg and had a peripherally inserted central catheter successfully inserted in his or her arm between June 2004 and November 2005. The primary outcome was the occurrence of partial or complete deep vein thrombosis evaluated by clinical examination, ultrasonography and venous angiography.

RESULTS

A total of 214 patients (101 girls, 113 boys) were included in the study. Partial or complete deep vein thrombosis occurred in 20 patients, for an incidence of 93.5 per 1000 patients and 3.85 per 1000 catheter-days. Only 1 of the cases was symptomatic. In the univariable analyses, the only variable significantly associated with deep vein thrombosis was the presence of factor II mutation G20210A (odds ratio 7.08, 95% confidence interval 1.11-45.15, p = 0.04), a genetic mutation that increases the risk of a blood clot and that was present in 5 (2.3%) of the 214 patients.

INTERPRETATION

The incidence of deep vein thrombosis related to peripherally inserted central catheters in our study was lower than the incidence related to centrally inserted venous catheters described in the pediatric literature (11%-50%).

Risk factors for recurrent venous thromboembolism in the European collaborative paediatric database on cerebral venous thrombosis: a multicentre cohort study

Background

The relative importance of previous diagnosis and hereditary prothrombotic risk factors for cerebral venous thrombosis (CVT) in children in determining risk of a second cerebral or systemic venous thrombosis (VT), compared with other clinical, neuroimaging, and treatment variables, is unknown.

Methods

We followed up the survivors of 396 consecutively enrolled patients with CVT, aged newborn to 18 years (median 5·2 years) for a median of 36 months (maximum 85 months). In accordance with international treatment guidelines, 250 children (65%) received acute anticoagulation with unfractionated heparin or low-molecular weight heparin, followed by secondary anticoagulation prophylaxis with low-molecular weight heparin or warfarin in 165 (43%).

Results

Of 396 children enrolled, 12 died immediately and 22 (6%) had recurrent VT (13 cerebral; 3%) at a median of 6 months (range 0·1–85). Repeat venous imaging was available in 266 children. Recurrent VT only occurred in children whose first CVT was diagnosed after age 2 years; the underlying medical condition had no effect. In Cox regression analyses, non-administration of anticoagulant before relapse (hazard ratio [HR] 11·2 95% CI 3·4–37·0; p<0·0001), persistent occlusion on repeat venous imaging (4·1, 1·1–14·8; p=0·032), and heterozygosity for the G20210A mutation in factor II (4·3, 1·1–16·2; p=0·034) were independently associated with recurrent VT. Among patients who had recurrent VT, 70% (15) occurred within the 6 months after onset.

Conclusion

Age at CVT onset, non-administration of anticoagulation, persistent venous occlusion, and presence of G20210A mutation in factor II predict recurrent VT in children. Secondary prophylactic anticoagulation should be given on a patient-to-patient basis in children with newly identified CVT and at high risk of recurrent VT. Factors that affect recanalisation need further research.

Genetic prothrombotic mutations are common in neonates but are not associated with umbilical catheter-associated thrombosis

OBJECTIVE

To evaluate the prevalence of hereditary prothrombotic mutations, and their effect on the incidence and severity of umbilical arterial or venous catheter (UAC or UVC)-associated thrombosis.

STUDY DESIGN

All neonates with a UAC or UVC were studied prospectively for the presence, severity and timing of thrombosis with duplex Doppler ultrasound scan. Genetic testing for factor V Leiden (FVL), prothrombin mutation (PTm) and methylene-tetrahydrofolate reductase (MTHFR) mutations was performed using PCR and restriction fragment length polymorphism assays.

RESULT

Umbilical catheter (UC)-associated thrombosis developed in 16/53 (31%) neonates; 23% of UACs and 22% of UVCs were associated with thrombosis. The prevalence of a significant prothrombotic mutation was present in 10/51 (20%) of infants: FVL (8%), MTHFR667 homozygosity (10%), MTHFR1298 homozygosity (2%) and PTm (0%). There was no increase in the risk of UC-associated thrombus in patients carrying these prothrombotic mutations; our study had the power to detect a 2.5-fold increased risk of thrombosis for any of these significant mutations. In addition, MTHFR667 heterozygosity was found in 41% of infants and MTHFR1298 heterozygosity in 52% and also were not associated with increased risk of UC-associated thrombus. The risk of MTHFR double heterozygosity (db het) was 14%, the risk of a significant or db het was 17/51 (33%) and the risk of any mutation was 90%.

CONCLUSION

Prothrombotic genetic mutations are common in our Neonatal Intensive Care Unit population but do not appear to increase the risk of UC-associated thrombosis.

Efficacy of family history in determining thrombophilia risk

STUDY OBJECTIVE

This retrospective study sought to examine the importance of family history of cardiovascular disease (CVD) or venous thromboembolism (VTE) in predicting risk for an inherited thrombophilia.

DESIGN/METHODS

A cohort of 88 adolescent females who had a thrombophilia panel in the last three years was identified for this retrospective chart review. Family history data of CVD or VTE were collected in addition to laboratory results from the thrombophilia screen.

SETTING

Adolescent patients who had a thrombophilia screen within the last three years at University OB-GYN Associates, Louisville, KY.

RESULTS

Within the cohort (n=88), 21% of patients were found to have a documented thrombophilia. At least 47% of individuals diagnosed with thrombophilia had more than one screening abnormality. A family history of VTE was noted to have a positive predictive value (PPV) of 40% and a negative predictive value (NPV) of 88% for detection of thrombophilia. Patients with a family history of CVD alone carried a PPV of 24% and NPV of 100%. Finally, among individuals with both family history risk factors, PPV was strengthened at 52% while NPV remained unchanged.

CONCLUSIONS

Within the last decade, inherited thrombophilias have gained more clinical interest. While thrombophilia disease prevalence data is available for the adult population, there remains a paucity of data in adolescents. Our results reinforce the importance for screening adolescent females, prior to contraceptive administration, if family history risk factors exist.

Myocardial infarction in an adolescent: anomalous origin of the left main coronary artery from the right coronary sinus in association with combined prothrombotic defects

We present the case of a 15-year-old boy with clinical features of an acute myocardial infarction. Angiography revealed a complete obstruction of the left main coronary artery. A coronary-aorto-bypass graft was undertaken immediately. Cardiac computed tomography demonstrated an anomalous origin of the left main coronary artery from the right coronary sinus of the aorta. A thrombophilic state with a heterozygote genotype for prothrombin G20210 mutation, a C677T methylenetetrahydrofolate reductase gene mutation, and a protein C type 1 deficiency was detected. No other embolic source could be identified. The patient recovered with persistent left ventricular dysfunction. He is now taking the anticoagulant warfarin. Combined prothrombotic defects in combination with additional risk factors such as coronary anomalies can lead to myocardial infarction even in children and adolescents.

Role of elevated alpha2-macroglobulin revisited: results of a case-control study in children with symptomatic thromboembolism

OBJECTIVE

alpha(2)-Macroglobulin (alpha2MG) is a broad-spectrum protease inhibitor that is known to neutralize alpha-thrombin, plasmin, and activated protein C, which suggests that it has anticoagulant as well as procoagulant properties. The present study was conducted to evaluate the role of alpha2MG in children with venous thromboembolism [VTE: paradoxical embolism causing ischemic stroke (IS) or deep-vein thrombosis (DVT)].

METHODS

alpha2MG levels measured after acute VTE onset in white patients were compared with data obtained from age- and gender-matched healthy controls. In addition, to compare the rate of elevated alpha2MG and prothrombotic risk factors [factor V G1691A, prothrombin G20210A, raised lipoprotein (a)] between patients and controls and to evaluate the interaction between elevated alpha2MG levels and other thrombophilias, odds ratios (ORs) together with 95% confidence intervals (CIs) were estimated using a logistic regression model. The model was adjusted for age and fibrinogen.

RESULTS

alpha2MG levels were significantly higher in patients than in controls (320/139-524 vs. 302/109-406; P = 0.005). In the group of patients (IS n = 103; DVT n = 92), the risk of symptomatic thromboembolism was significantly increased with elevated alpha2MG levels, with a gradual increase per mg dL(-1). In addition, when elevated alpha2MG levels > 90th percentile were compared with values below the cut-off, including established prothrombotic risk factors in the multivariate analysis, patients had a significantly increased OR/95% CI for fibrinogen-adjusted alpha2MG levels (IS, 5.9/1.9-18.3; DVT, 7.2/2.1-24.4).

CONCLUSIONS

The procoagulant properties of elevated alpha2MG levels independently increase the odds of stroke and DVT in white children.

The influence of risk factors in promoting thrombosis during childhood: the role of acquired factors

Thrombo-embolism in childhood is a multifactorial disorder. The present study is a case-control study that investigated the role of genetic and acquired risk factors in 60 children with thrombosis and compared the results with the controls. Acquired and inherited risk factors precipitating thrombosis were present in 75 and 40% of the thrombotic children, respectively. The most frequent acquired risk factor was infection (58%). Of the genetic factors, factor V G20210A was the most common (38%). The comparison of the genetic and acquired risk factors in thrombotic versus nonthrombotic settings identified that acquired factors played a more significant role in causing thrombosis (OR:14.44; 95% CI: 7.05-29.94, p < .001). This study has clearly suggested that the prevention of acquired risk factors, particularly infection, could decrease the risk of thrombosis in pediatric cases.

Iliofemoral Deep Vein Thrombosis in Childhood; Developing a Management Protocol

OBJECTIVE

To develop an evidence-based protocol for the management of iliofemoral deep vein thrombosis (IDVT) in childhood.

METHODS

A search of the literature was undertaken. All publications pertaining to IDVT in childhood were analysed and then categorised according to their level of evidence. Recommendations were then made on the basis of this.

RESULTS

The commonest presenting symptoms were pain and swelling in the affected limb (evidence level II). Predisposing risk factors of special significance in children included the recent use of a venous access device, malignancy, prothrombotic disorders, infection, surgery and congenital venous anomalies (evidence level II). The most frequently described imaging modalities were B-mode ultrasonography, duplex, venography, and helical CT (evidence level III). The mainstay of treatment was anticoagulation with LMWH alone or followed by warfarin (evidence level I). Early clot removal through catheter-directed thrombolysis or surgical thrombectomy has been shown to be beneficial (evidence level II/III). There is little evidence for the benefit of early mobilisation and compression therapy in childhood.

CONCLUSION

Level I evidence relating to IDVT in childhood is sparse. The possibility of IDVT should be considered when examining a child with a swollen and painful limb. Imaging should be with duplex ultrasound, followed by spiral CT to include assessment of the IVC. A thrombophilia screen should be taken prior to anticoagulation with LMWH (and warfarin). Thrombolysis should be considered in cases of extensive IDVT.

Elevated alpha1-antitrypsin is a risk factor for arterial ischemic stroke in childhood

Alpha1-antitrypsin (alpha1-AT) is a physiological inhibitor of activated protein C (APC) and therefore decreased APC activity. APC itself causes an anticoagulant effect by inactivating factors Va and VIIIa. The present case-control study was performed to evaluate the role of the elevated alpha1-AT concentration in pediatric patients with ischemic stroke (IS). alpha1-AT concentrations were measured along with established prothrombotic risk factors 6-12 months after the acute thrombotic onset in 81 Caucasian children with IS aged 1 month to 18 years. The cutoff values defined as age-dependent 90th percentiles were obtained from 229 healthy controls. Median (range) values of alpha1-AT were significantly higher in patients compared with control subjects [122.0 mg/dl (61.4-224.0) vs. 114.0 mg/dl (66.8-156.0); p = 0.016]. In addition, 14 of the 81 patients (17.3%) compared with 10 of the 162 controls (6.2%) had alpha1-AT concentrations above the 90th age-dependent percentiles (p = 0.012). Multivariate analysis performed in a 1:2 matched case-control setting adjusted for the presence of established prothrombotic risk factors showed a significantly increased odds ratio (OR) and 95% confidence interval (CI) for patients with elevated alpha1-AT >90th percentiles and IS (OR/CI: 4.0/1.64-9.92; p = 0.0024). Data shown here give evidence that total alpha1-AT concentrations above the 90th age-dependent percentiles independently increase the risk of IS 4.0-fold in Caucasian children.

Long-term treatment of thrombosis with enoxaparin in pediatric and adolescent patients

Thrombosis is a rare event in childhood and adolescence. Nevertheless, increasing numbers of invasive diagnostic and therapeutic procedures also result in increasing numbers of thromboses in pediatric cases, necessitating effective antithrombotic treatment regimens. In recent years, low-molecular-weight heparins (LMWH) in particular have been proved to be a safe and effective alternative to unfractioned heparins. However, the application of LMWH in pediatric patients has not been supported by a single controlled study so far. Furthermore, there is no official approval of these drugs for children. In this pilot study 27 children with deep venous thromboses (DVT) were treated with the LMWH enoxaparin at a dosage of 1.5 mg/kg body weight b.i.d. in neonates and infants and 1 mg/kg body weight b.i.d. in children. This dosage was lowered for prophylaxis if therapeutic success was achieved. The aim of the study was to investigate both, efficacy with respect to patency rates and safety during acute and long-term follow-up. Sufficient therapeutic success required a rapid production of anti-Xa target activity and was reached in 85% of the treated patients, who showed patency of the affected vessel at last follow-up. The mean duration of treatment with full dosage was 16.5 days, followed by prophylaxis over a mean duration of 9.8 months. Rethrombosis or adverse events including heparin-induced thrombocytopenia were not observed in any patient. In conclusion, enoxaparin provides an effective and safe alternative to unfractioned heparins in the treatment of thrombosis in infancy, childhood and adolescence.

Legg-perthes disease and heritable thrombophilia

The etiology of Perthes' disease is unclear. Recent reports have suggested that inheritable thrombophilic disorders may be one of its pathogenetic causes. The G20210A prothrombin gene, factor V Leiden, and MTHFR C677T mutations have been identified as predisposing genetic factors for thrombosis. Ninety children diagnosed with Perthes' disease were studied. A family history of thrombosis and any other personal thromboembolic events were researched. PCR and endonuclease digestion were used to analyze factor V Leiden, prothrombin G20210A, and MTHFR C677T. Two hundred healthy donors were included as a control group. No patient had a family or personal history of early thrombotic events. Four children with Perthes' disease (4.4%) were heterozygous for G20210A polymorphism compared with controls (odds ratio: 2.07; 95% confidence interval: 0.40-8.46). No association between factor V Leiden and Perthes' disease was observed. Three patients (3.33%) were heterozygous for factor V Leiden (odds ratio: 1.36; 95% confidence interval: 0.32-5.84). The prevalence of different genotypes of C677T MTHFR did not show statistical differences compared with controls. Eleven patients were homozygous for this polymorphism (odds ratio: 1.02; 95% confidence interval: 0.42-2.44). This study does not support the screening of this group of polymorphism in patients with Perthes' disease.

Prothrombin G20210A mutation in Turkish children with thrombosis and the frequency of prothrombin C20209T

The prothrombin G20210A mutation has been described as the second most common genetic risk factor in thrombotic patients. Recently a new prothrombin gene variant namely prothrombin C20209T has also been found to be associated with thrombosis. In the present study the frequency of these two thrombin variants have been searched in two different groups. Group 1: A total of 377 children with thrombosis were analyzed during 7 years between January 1997 and 2004 and screened for prothrombin G20210A mutation. Twenty-four of 387 children (6.3%) with thrombosis were diagnosed as having PT G20210A mutation. The mean age of the patients was 6.1 years (median: 6 years, range: 4 months to 17 years, 15 male, 9 female). Six of 24 children were below 2 years of age (25%). Fifteen of 24 children (62.5%) had arterial thrombosis, most of whom (93.3%) had cerebral infarct. Group 2: The prothrombin C20209T variant has been analyzed in 200 thrombotic patients and in 200 healthy subjects. None of the thrombotic patients and healthy individuals carried the prothrombin C20209T variant. In conclusion, arterial thrombosis as the cerebral infarct is the most prominent type of thrombosis in children with prothrombin G20210A mutation. It seems that the prothrombin C20209T variant is not an important risk factor for the population studied.

Thromboembolic Diseases in Neonates and Children

Acquired and inherited prothrombotic risk factors increase the risk of thrombosis in neonates, infants and children. After suffering thrombosis white paediatric patients should be screened for common gene mutations, i.e. the factor V G1691A, factor II G20210A and MTHFR C677T genotypes, rare inherited prothromboticrisk factors, i.e. deficiencies of protein C,protein S, and antithrombin, plasminogen, probably inherited risk factors, i.e. fibrinogen, factor VIIIC, factor XII, new candidates, i.e. elevation of lipoprotein (a),and fasting homocysteine concentrations (3-6 months after thrombotic onset). Data interpretation is based on age-dependent reference ranges or the identification of causative gene mutations/polymorphisms with respect to individual ethnic backgrounds.

Analysis of some clinical and laboratory aspects of adolescent patients with thrombosis

A total of 360 pediatric patients aged 1 month to 18 years were diagnosed as having thrombosis between January 1998 and April 2003. Of these patients, those aged 11-18 years (n=131) were regarded as adolescents and the rest as children. The proportion of adolescents in the whole group excluding the neonates was 36%. The peak age of diagnosis in adolescents was 11-14 years, comprising 58% of all thrombotic events in adolescents. In 73% of the adolescents, there was at least one risk factor. The four most common underlying disorders were infection, malignancy, connective tissue and cardiac disorders, in decreasing order of frequency. In children, on the other hand, infection was followed by congenital heart disease, malignancy and liver disease. Three common types of thrombosis in adolescents were deep venous thrombosis, cerebro-vascular events and portal venous thrombosis, while cerebro-vascular events were the most common in children. The frequency of factor V G1691A mutation in the adolescents (22.1%) was significantly higher than that found in a group of healthy controls (7.4%) and this mutation was associated with a 3.6-fold increase in the risk of developing thrombosis (95% confidence interval, 1.4-9.0). The carrier frequency of prothrombin G20210A mutation (3.1%) in adolescents did not differ significantly from that of the healthy population (2.3%) and no association was observed between this mutation and a risk of developing thrombosis in this group (odds ratio, 1.3; 95% confidence interval, 0.2-7.5). The rate of recurrent thrombosis was 6%.

Analysis of pediatric thrombotic patients in Turkey

This study analyzes the data of thrombotic children who were followed up in different pediatric referral centers of Turkey, to obtain more general data on the diagnosis, risk factors, management, and outcome of thrombosis in Turkish children. A simple two-page questionnaire was distributed among contact people from each center to standardize data collection. Thirteen pediatric referral centers responded to the invitation and the total number of cases was 271. All children were diagnosed with thromboembolic disease between January 1995 and October 2001. Median age at time of first thrombotic event was 7.0 years. Of the children 4% of the cases were neonates, 12% were infants less than 1 year old, and 17% were adolescents. Thromboembolic event was mostly located in the cerebral vascular system (32%), deep venous system of the limbs, femoral and iliac veins (24%), portal veins (10%), and intracardiac region (9%). Acquired risk factors were present in 86% of the children. Infection was the most common underlying risk factor. Inherited risk factors were present in 30% of the children. FVL was the most common inherited risk factor. Acquired and inherited risk factors were present simultaneously in 19% of the patients. Eleven children had a history of familial thrombosis. Due to the local treatment preferences, the treatment of the children varied greatly. Outcome of the 142 patients (52%) was reported: 88 (62%) patients had complete resolution, 47 (33%) had complications, 12 (9%) had recurrent thrombosis, and 34 (24%) died. Three children (2.1%) died as a direct consequence of their thromboembolic disease. The significant morbidity and mortality found in this study supports the need for multicentric prospective clinical trials to obtain more generalizable data on management and outcome of thrombosis in Turkish children.

Protein C system defects in Indian children with thrombosis

As ethnic variations are known to exist in inherited genetic defects, the clinico-haematological profile of Indian children with thrombophilia may be different from that of Caucasians. The aim of the study was to analyse the phenotypic and genotypic causes of thrombophilia in Indian children. Forty patients with arterial (21 patients) and venous (19 patients) thrombosis were the subjects of the study. Their age ranged from 6 days to 15 years. All of the patients were initially screened by Pro C Global assay. Activated protein C resistance (APCR) was measured. In cases with low Pro C Global values, protein C (PC), protein S (PS) and factor V G1691A, prothrombin G20210A and MTHFR C677T polymorphism were tested in all 40 cases. Of the 21 patients with arterial thrombosis, 4 (19%) had PC deficiency, 7 (33.3%) had PS deficiency and 1 (4.8%) had combined deficiency of PC and PS. Of the 19 patients with venous thrombosis, 5 (26.3%) each had PC and PS deficiency and 4 (21%) had combined PC and PS deficiency. Heterozygous factor V G1691A defect was seen in one (4.8%) patient with arterial thrombosis and three (15.8%) patients with venous thrombosis. Heterozygous MTHFR C677T polymorphism was seen in five (23.8%) patients with arterial thrombosis and in four (21%) patients with venous thrombosis. Prothrombin G20210A polymorphism was absent in all patients and controls. Protein C system defect is common in Indian children with thrombosis.

Renal venous thrombosis in neonates: prothrombotic risk factors and long-term follow-up

The present study was designed to evaluate prothrombotic risk profiles in 59 consecutively recruited white neonates with renal venous thrombosis (RVT). The rates of prothrombotic risk factors (PRs)—for example, the factor V (FV) 1691G&gt; A mutation, the factor II (FII) 20210G&gt; A variant, antithrombin (AT), protein C (PC), protein S (PS), elevated lipoprotein(a) (Lp(a)), total fasting plasma homocysteine (tHcy) levels, and anticardiolipin antibodies (ACAs)—were compared with those of 118 healthy control children. At onset, 32 (54.2%) of the 59 neonates showed underlying clinical conditions; 40 (67.8%) of them and 23 (85.2%) of the 27 infants with idiopathic RVT showed at least one PR. Univariate analysis revealed significantly elevated odds ratios/95% confidence intervals (ORs/95% CIs) for FV and Lp(a). Additionally, PC/AT deficiency and ACAs were found significantly more often in the patient group (P = .04). Multivariate analysis calculated significant ORs/95% CIs only for FV (OR, 9.4; 95% CI, 3.3-26.6) and elevated Lp(a) (OR, 7.6; 95% CI, 2.4-23.8). Of the 59 neonates investigated, 53 revealed renal atrophy, and 13 children additionally suffered from severe arterial hypertension. In conclusion, the present study demonstrates the significance of genetic PR—especially the FV mutation and elevated Lp(a)—for the etiology of neonatal RVT.

The factor V G1691A mutation is a risk for porencephaly: A case-control study

This study was initiated to investigate prothrombotic risk factors in children with porencephaly. 76 porencephalic and 76 healthy infants were investigated for factor V (FV) G1691A mutation, factor II G20210A variant, methylenetetrahydrofolate reductase (MTHFR) C677T genotype, lipoprotein (a), protein C, protein S, and antithrombin. Only the FV mutation (p = 0.005) and combinations of two or three different risk factors (p = 0.003) were significantly associated with porencephaly. These data give evidence that the FV G1691A mutation and a combination of prothromboic factors play a major role in the development of childhood porencephaly.

[Non-Hodgkin's lymphoma with protein S deficiency]

Venous thrombosis is rare in children. It can be either acquired or of constitutional origin. Thrombosis during non-Hodgkin lymphoma remains exceptional and is usually locally associated to the tumoral process, raising the issue of its tumoral or cruoric nature. The treatment is based on anticoagulation concomitantly to chemotherapy. We report on a 4-year-old boy admitted for mediastinal non-Hodgkin lymphoma, who developed a thrombosis of the superior vena cava associated to protein S-deficiency. The mechanism of thrombosis may have been multifactorial: associated protein S-deficiency, vascular compression, tumoral process and chemotherapy.

Pediatric venous thromboembolic disease in one single center: congenital prothrombotic disorders and the clinical outcome

To learn more about the frequencies of congenital prothrombotic disorders in pediatric venous thromboembolism (VTE) and the outcome of this disease, we evaluated consecutive patients from 0 to 18 years with objectively diagnosed VTE at a single tertiary center over a 12-year period. We included 100 patients, with a median age at diagnosis of 1.0 year (range 2 days to 17 years). At least one underlying clinical condition was present in 96% of the patients. Factor (F)V G1691A mutation was present in 13%, FII G20210A mutation in 3%, antithrombin deficiency in 1%, protein C deficiency in 1% and protein S deficiency in 1% of the tested patients. Combined defects were present in 2.6% of the 77 patients with a complete work-up. Positive family history appeared to be the only predictor for positive testing for congenital disorders (OR 14.9, 95% CI 1.9-113). The overall mortality rate was 20%. The cumulative recurrence-free survival was 92% after 1 year of follow-up, and 82% after 7 years. The incidence and severity of the post-thrombotic syndrome was analyzed in a subgroup of 33 patients with VTE of the lower extremities. Twenty-three (70%) patients developed PTS: moderate in three and mild in 20 patients. In conclusion, congenital prothrombotic disorders seem to play a role in the development of pediatric VTE, and the risk of complications of this disease is high.