Clinical and laboratory characteristics of children with venous thromboembolism and protein C-deficiency: an observational Israeli-German cohort study

Clinical Impact of Heritable Thrombophilia on Neonatal-Onset Thromboembolism: A Nationwide Study in Japan

OBJECTIVE

To clarify the incidence and genetic risk of neonatal-thromboembolism, we conducted a nationwide study exploring the impact of thrombophilia on neonatal-thromboembolism in Japan.

STUDY DESIGN

A questionnaire survey was conducted for perinatal centers in Japan, focusing on the clinical expression, genotype, treatment, and outcome of patients who developed thromboembolism within 28 days of birth from 2014 to 2018.

RESULTS

The estimated incidence of neonatal-thromboembolism was 0.39 cases per 10 000 live births. Intracranial lesions and purpura fulminans occurred in 66 and 5 of 77 patients, respectively. Fifty-eight (75.3%) infants presented within 3 days after birth. Four (5.2%) died, and 14 (18.2%) survived with disability. At the diagnosis, <20% plasma activity of protein C was noted in 16 infants, protein S (in 2), and antithrombin (in 1). Thirteen genetic tests identified 4 biallelic and 5 monoallelic protein C-variants but no protein S- or antithrombin-variants. Protein C-variants had purpura fulminans (P < .01), ocular bleeding (P < .01), positive-family history (P = .01), and death or disability (P = .03) more frequently than others. Protein C-variants were independently associated with disability (OR 5.74, 95% CI 1.16-28.4, P = .03) but not death. Four biallelic variants had serious thrombotic complications of neurologic disability, blindness, and/or amputation. Three monoallelic variants survived without complications. The only protein C-variant death was an extremely preterm heterozygote infant.

CONCLUSIONS

Monoallelic protein C-variants had a higher incidence of neonatal-thromboembolism than biallelic variants. Thrombophilia genetic testing should be performed in the setting of neonatal-thromboembolism and low protein C to identify the underlying genetic defect.

Neonatal thrombosis: risk factors and principles of prophylaxis

Data analysis on the pathogenesis and risk factors of neonatal thrombosis was carried out. The main risk factor of any neonatal thrombosis is central catheter installment, but other maternal, fetal and neonatal factors should be taken into consideration. We discuss the epidemiology of neonatal thrombosis and the main features of the hemostasis system in newborns, the most significant risk factors, including genetic and acquired thrombophilia. We consider the von Willebrand factor activity and ADAMTS-13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) level in the development of neonatal thrombotic microangiopathy. Finally, we discuss the basic principles of prevented neonatal thrombosis by using low molecular weight heparins.

Severe Protein C Deficiency due to Novel Biallelic Variants in PROC and Their Phenotype Correlation

Severe protein C deficiency due to biallelic PROC mutations is an extremely rare thrombophilia, most commonly presenting during the neonatal period as purpura fulminans. Despite treatment, severe morbidity and mortality are frequent. The current study reports 3 unrelated patients harboring novel homozygous PROC mutations and their clinical phenotypes. We discuss how the cytoprotective activity of protein C and its role in the stabilization of endothelial barriers may account for the unique symptoms of this thrombophilia.

Spontaneous neonatal renal vein thrombosis, a known pathology without clear management guidelines: An overview

Renal vein thrombosis (RVT) was first described in 1837 by Rayer. Although tremendous progress has been achieved in the comprehension of its pathophysiology, its management remains controversial over 20 decades later. Therapeutic modalities vary from supportive measures alone to the utilization of thrombolytic agents whose protocols are derived from adult medicine. This review aims to show how difficult the treatment of RVT still is, especially with regard to the prognosis. The majority of affected neonates end with various renal complications (renal atrophy, dysfunction, hypertension, etc.). Like others, we suggest that simple unilateral RVT be managed conservatively, while thrombolytic agents may be attempted in unilateral RVT with extension to VCI and in bilateral RVT. Further studies are needed to reach appropriate consensual guidelines.

Recurrent stroke: the role of thrombophilia in a large international pediatric stroke population

Risk factors for arterial ischemic stroke in children include vasculopathy and prothrombotic risk factors but their relative importance to recurrent stroke is uncertain. Data on recurrent stroke from databases held in Canada (Toronto), Germany (Kiel-Lübeck/Münster), and the UK (London/Southampton) were pooled. Data were available from 894 patients aged 1 month to 18 years at first stroke (median age, 6 years) with a median follow-up of 35 months. Among these 894 patients, 160 (17.9%) had a recurrence between 1 day and 136 months after the first stroke (median, 3.1 months). Among 288 children with vasculopathy, recurrence was significantly more common [hazard ratio (HR) 2.5, 95% confidence interval (95% CI) 1.92-3.5] compared to the rate in children without vasculopathy. Adjusting for vasculopathy, isolated antithrombin deficiency (HR 3.9; 95% CI: 1.4-10.9), isolated elevated lipoprotein (a) (HR 2.3; 95% CI: 1.3-4.1), and the presence of more than one prothrombotic risk factor (HR 1.9; 95% CI: 1.12-3.2) were independently associated with an increased risk of recurrence. Recurrence rates calculated per 100 person-years were 10 (95% CI: 3-24) for antithrombin deficiency, 6 (95% CI: 4-9) for elevated lipoprotein (a), and 13 (95% CI: 7-20) for the presence of more than one prothrombotic risk factor. Identifying children at increased risk of a second stroke is important in order to intensify measures aimed at preventing such recurrences.

Utility of current thrombophilia screening in young patients with stroke and TIA

Introduction

Approximately 40% of strokes in young adults are cryptogenic. The diagnostic yield of thrombophilia screening remains controversial. We aimed to determine utility of current thrombophilia testing for young patients with stroke and transient ischaemic attack (TIA).

Methods

We present a retrospective review of all patients with stroke and TIA ≤60 years presenting to University College London Hospital stroke unit and daily TIA clinic from 1 January 2015 to 1 August 2016. Consecutive clinical records and thrombophilia tests, including factor V Leiden (FVL), prothrombin G20210A mutation (PGM), antiphospholipid antibody (APA), and protein S, C and antithrombin (AT) levels, were reviewed.

Results

The mean age of 628 patients with stroke and TIA was 49.1 years (SD 9.2). Thrombophilia testing was performed in 360 (57%) patients, including 171 with stroke and 189 with TIA. Positive tests were found in 50 (14%) patients, of whom 24 patients were <50 years. Positive results were found in 36 (10%) with acute ischaemic stroke, 4 (1%) with haemorrhagic stroke and 10 (3%) with TIA. Thirteen patients (4%) had homozygous/heterozygous FVL or PGM, and 27 (7.5%) had positive APA (anticardiolipin antibody, anti-β2 glycoprotein antibody or lupus anticoagulant). Of 27 (7.5%) patients with protein C, S or AT deficiency, 10 (2.8%) had primary deficiency, presumed hereditary with other secondary causes excluded. 9% of patients with protein C, S or AT and 27% with APA were followed by confirmatory testing.

Conclusion

Thrombophilia testing was positive in only 14% of cases overall. Thrombophilia mutations and protein C, S or AT abnormalities were found rarely and were very uncommon in patients with TIA. Follow-up of abnormal results was generally poor for all groups, which further limited the impact of the thrombophilia testing policy.

Thrombophilia testing in children: What and when should be tested?

Venous thrombosis (VTE) in children is gaining increased awareness and apart from underlying medical conditions, recently reported systematic reviews on pediatric VTE (70% provoked) have shown significant associations between thrombosis and presence of inherited thrombophilic risk factors (IT), such as protein C-, protein S- and antithrombin deficiency, mutations of factor 5 (F5: rs6025) and factor 2 (F2: rs1799963), even more pronounced when combined IT were involved. Although we have learned more about the pathophysiology of VTE with the increased discovery of IT evidence is still lacking as to whether IT influence the clinical outcome in pediatric VTE. It still remains controversial as to whether children with VTE or offspring from thrombosis-prone families benefit from IT screening. Thus, IT testing in children should be individualized. If the decision "pro screening" is discussed as an appropriate option in adolescents with unprovoked VTE and in children with a positive family history for VTE screening should be performed in a specialized coagulation unit for acquired or inherited and prothrombotic defects based on the individual population background. Apart from the laboratory assessment for the presence/absence of lupus anticoagulants and antiphospholipid antibodies screening should be performed beyond the acute VTE onset and after withdrawal of anticoagulant medication possibly influencing laboratory results.

Advances in predicting venous thromboembolism risk in children

Paediatric venous thromboembolism (VTE) is a rare disorder but a rising incidence has been observed in recent years, due to improved VTE diagnosis and increased use of central venous catheters in the treatment of severe diseases. Risk assessment strategies are well established for adult patients, however, similar guidelines for paediatric patients are largely lacking. Several risk prediction tools have been reported in recent literature, which make use of established risk factors to assess VTE risk in paediatric subgroups, such as hospitalised children, cancer-diagnosed children and paediatric trauma patients. Although these models suffer several limitations regarding their study size and heterogeneous selection of predictor variables, they offer potential for improving the thromboprophylaxis management in these children. Here, we give an overview on recently reported risk prediction models for paediatric VTE.

Role of protein S deficiency in children with venous thromboembolism

Venous thromboembolism [TE] is a multifactorial disease, and protein S deficiency [PSD] constitutes a major risk factor. In the present study the prevalence of PSD and the clinical presentation at TE onset in a cohort of children is reported. In 367 unselected paediatric patients with TE (age 0.1–18 years) recruited between July 1996 and December 2013, a comprehensive thrombophilia screening was performed along with recording of anamnestic data. Thirty of 367 paediatric patients (8.2 %) derived from 27 families had PSD. Mean age at first TE onset was 14.5 years (range 0.1 to 18). Thrombotic locations were cerebral veins (n=8), calf vein TE (n=3) deep veins (DVT) of the leg (n=12), DVT & pulmonary embolism (n=5) and intra-cardiac veins (n=1) or purpura fulminans (n=1). PSD co-occurred with the factor 5 mutation at rs6025 or the homozygous factor 2 susceptibility variant at rs1799963 in one case each. The Heerlen polymorphism detected in five children presented with milder PSD. In 18 patients (60 %) a concomitant risk factor for TE was identified. A second TE event within primarily healthy siblings occurred in three of 27 PSD families (11.0 %). In this cohort of children with symptomatic TE, the prevalence of PSD adjusted for family status was 7.4 %. Given its clinical implication for patients and family members, thrombophilia testing should be performed and the benefit of medical or educational interventions should be evaluated in this high-risk population.

Risk factors for symptomatic venous and arterial thromboembolism in newborns, children and adolescents - What did we learn within the last 20years?

Venous thrombosis (VTE) in children is increasingly diagnosed, as advanced medical care has increased treatment intensity of hospitalized pediatric patients. The aim of this review was to summarize the data available and to discuss the controversial issue of thrombophilia screening in the light of the pediatric data available. Follow-up data for VTE recurrence in children suggest a recurrence rate between 3% (neonates) and 21% in individuals with unprovoked VTE. Apart from underlying medical conditions, recently reported systematic reviews on pediatric VTE (70% provoked) have shown significant associations between thrombosis and presence of protein C-, protein S- and antithrombin deficiency, factor 5 (F5: rs6025), factor 2 (F2: rs1799963), even more pronounced when combined inherited thrombophilias [IT] were involved. The F2 mutation, protein C-, protein S-, and antithrombin deficiency did also play a significant role at VTE recurrence. Although we have learned more about the pathophysiology of VTE with the increased discovery of IT evidence is still lacking as to whether IT influence the clinical outcome in pediatric VTE. It still remains controversial as to whether children with VTE or offspring from thrombosis-prone families benefit from IT screening. Thus, IT testing in children should be individualized.

Impact of high risk thrombophilia status on recurrence among children and adults with VTE: An observational multicenter cohort study

BACKGROUND

Antithrombin [AT]-, protein C [PC]- or protein S [PS]-deficiency [D] constitutes a major risk factor for venous thromboembolism [VTE]. Primary study objective was to evaluate if the clinical presentation at first VTE onset differs between children and adults and to compare the individual recurrence risk among patients with respect to age at onset and their thrombophilia status ATD, PCD or PSD.

METHODS/PATIENTS/RESULTS

In 137 of 688 consecutively enrolled pediatric and adult VTE patients we calculated the absolute risk of VTE recurrence and event-free-survival adjusted for thrombophilia and positive family VTE history. At first VTE children manifested i) with a lower rate of pulmonary embolism, ii) a higher rate of cerebral vascular events or multiple VTEs, and iii) showed a higher proportion of unprovoked VTE compared to adolescents and adults. Adult patients reported more often a positive VTE history compared to younger study participants. The adjusted odds of recurrence in adults was 2.05 compared to children.

CONCLUSION

At disease manifestation children and adults differ with respect to i) thrombotic locations, ii) percentage of unprovoked versus provoked VTE, and iii) different rates of positive VTE family histories. Furthermore, adults showed a two-fold increase risk of VTE recurrence compared to children.

Thrombophilic Gene Mutations in Relation to Different Manifestations of Venous Thromboembolism: A Single Tertiary Center Study

BACKGROUND

Venous thromboembolism (VTE) is a common and potentially lethal disorder that manifests mainly as deep vein thrombosis (DVT) of the extremities or pulmonary embolism (PE) and occurs as a consequence of genetic and environmental risk factors. We aimed to assess the role of inherited thrombophilia as a causative or additive factor in the development of VTE.

METHODS

The study included 310 patients (female: 154; mean age: 52.3 ± 16.9 years) with a first episode of VTE and 289 age- and sex-matched healthy controls. All participants underwent screening for thrombophilia-associated polymorphisms including factor V Leiden (FVL), prothrombin G20210A (PTG), factor V H1299 R (factor V HR2), factor XIII V34 L, β-fibrinogen-455 G>A, plasminogen activator inhibitor-1 4G/5G, human platelet antigen-1 a/b, methylene tetrahydrofolate reductase (MTHFR) C677 T, MTHFR A1298C, angiotensin-converting enzyme I/D, apolipoprotein B R3500Q, and apolipoprotein E (Apo E). In addition, serum homocysteine (Hcy) levels were measured.

RESULTS

In the patient group, 247 (80%) had isolated DVT, 43 (14%) had DVT plus PE, and 20 (6%) had isolated PE. The mean Hcy levels were similar in VTE subgroups and controls. Compared to controls, patients with isolated DVT, DVT plus PE, and isolated PE showed significantly higher frequencies for the following-heterozygous FVL mutation, isolated DVT (28.3%), DVT plus PE (44.2%), isolated PE (50%), controls (8.3%; P < .001); heterozygous PTG mutation, isolated DVT (11.3%), DVT plus PE (20.9%), isolated PE (25%), controls (5.9%; P < .01); Apo E 2/4, isolated DVT (9.7%), DVT plus PE (9.3%), isolated PE (5%), controls (1%; P < .01).The MTHFR A1298C mutation showed a significantly higher frequency in isolated patients with PE than in those with isolated DVT ( P = .006) and in controls ( P = .008). The frequencies of other genetic mutations or polymorphisms showed similar frequencies in all comparisons. In logistic regression analysis, heterozygous FVL mutation was the only independent predictor of VTE (odds ratio: 3.9, 95% confidence interval: 1.3-11.2; P = .012).

CONCLUSION

Except than FVL, PTG, and Apo E 2/4 mutations, many of aforementioned thrombophilic factors known to be associated with VTE did not demonstrate any relationship with VTE. Heterozygous mutation of FVL was an independent predictor for VTE.

Impact of high-risk thrombophilia status on recurrence among children with a first non-central-venous-catheter-associated VTE: an observational multicentre cohort study

Deficiency of antithrombin (AT), protein C (PC) or protein S (PS) constitutes a major risk factor for venous thromboembolism (VTE). Individuals at high risk for recurrence who benefit from screening need to be identified. The primary study objective was to determine the individual recurrence risk among children with a first non-central-venous-catheter-associated VTE with respect to their thrombophilia status and to evaluate if the clinical presentation at first VTE onset differs between children with AT, PC or PS deficiency versus no thrombophilia. We calculated the absolute risk of VTE recurrence and event-free-survival adjusted for thrombophilia, age, sex and positive family VTE history in 161 consecutively enrolled paediatric VTE patients. The presence of a deficiency relative to no thrombophilia was evaluated as a potential predictor of recurrence. Predictors for recurrence were AT deficiency (hazard ratio/95% CI: 6·5/2·46-17·2) and female gender (2·6/1·1-6·35). The annual recurrence rates (95% CIs) were 5·4% (2·6-10) in AT-deficient children, 1·3% (0·3-3·8) in patients with PC deficiency, 0·7% (0·08-2·4) in the PS-deficient cohort and 0·9% (0·4-1·8) in patients with no thrombophilia. Positive family VTE history or combined thrombophilias did not predict recurrence. Given the overall annual incidence rate of recurrence of 1·5% we suggest screening for AT deficiency in children with VTE.

[Haemostatic disorders in children]

Haemorrhagic and thrombotic events occur in both children and adults. The underlying causes are congenital or acquired disorders. In contrast to haemorrhagic disorders, inherited thrombotic disorders nearly exclusively in association with additional external risk factors lead to thrombotic events predominantly during the newborn period and adolescence. It is necessary to be aware of age-specific properties of coagulation in order to correctly interpret clinical and laboratory findings and to provide optimal care for children with haemorrhagic and thrombotic complications.

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.