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the Childhood Stroke Study GroupBackground-The present study was performed to assess the association of prothrombotic risk factors and underlying conditions (infections, vascular trauma, immobilization, malignancies, autoimmune diseases, renal diseases, metabolic disorders, obesity, birth asphyxia, cardiac malformations, and use of prothrombotic drugs) with cerebral venous thrombosis (CVT) in children. Methods and Results-From 1995 to 2002, 149 pediatric patients aged newborn to Ͻ18 years (median 6 years) with CVT were consecutively enrolled. In patients and in 149 age-and gender-matched children with similar underlying clinical conditions but without CVT, the factor V G1691A mutation, the factor II G20210A variant, lipoprotein(a) [Lp(a)], protein C, protein S, antithrombin, and antiphospholipid antibodies, as well as associated clinical conditions, were investigated. Eighty-four (56.4%) of the patients had at least 1 prothrombotic risk factor compared with 31 control children (20.8%; PϽ0.0001). In addition, 105 (70.5%) of 149 patients with CVT presented with an underlying predisposing condition. On univariate analysis, factor V, protein C, protein S, and elevated Lp(a) were found to be significantly associated with CVT. However, in multivariate analysis, only the combination of a prothrombotic risk factor with an underlying condition (OR 3.9, 95% CI 1.8 to 8.6), increased Lp(a) (OR 4.1, 95% CI 2.0 to 8.7), and protein C deficiency (OR 11.1, 95% CI 1.2 to 104.4) had independent associations with CVT in the children investigated. Conclusions-CVT in children is

SummaryBackgroundThe 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.MethodsWe 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%).ResultsOf 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.ConclusionAge 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.

for the Childhood Stroke Study GroupBackground and Purpose-The present study was performed to evaluate the rate of recurrent symptomatic thromboembolism with respect to prothrombotic risk factors and underlying clinical conditions. Methods-In a series of 215 consecutively enrolled neonates with arterial ischemic stroke (AIS), the factor V G1691A mutation, factor II G20210A variant, methylenetetrahydrofolate reductase (MTHFR) T677T genotype, lipoprotein (Lp) (a), antithrombin, protein C, protein S, and anticardiolipin antibodies (ACA) were investigated. Patient median follow-up was 3.5 years (range, 1 to 8 years). Results-During follow-up, 7 infants and children (3.3%) showed recurrent symptomatic thromboembolism (AIS, nϭ4; venous sinus thrombosis, nϭ2; deep vein thrombosis of the leg, nϭ1). The factor V mutation, factor II variant, elevated Lp(a) Ͼ30 mg/dL, protein C deficiency, and protein S or antithrombin deficiency were associated with first stroke onset.

Alterations in hemostasis leading to symptomatic thromboembolism have been observed in patients with acute lymphoblastic leukemia (ALL) receiving Escherichia coli asparaginase (CASP) combined with steroids. Moreover, hereditary prothrombotic risk factors are associated with an increased risk for venous thromboembolism in pediatric ALL patients treated according to the BFM 90/95 protocols (including CASP combined with prednisone during induction therapy). To assess whether the thromboembolic risk associated with established prothrombotic risk factors is modified by treatment modalities (prednisone or dexamethasone), the present analysis was performed. Three hundred thirty-six consecutively recruited leukemic children treated according to different BFM protocols (PRED group, n ‫؍‬ 280, 60 mg/m 2 prednisone; DEXA group, n ‫؍‬ 56, 10 mg/m 2 dexamethasone during induction therapy) were studied. Study end point was the onset of symptomatic vascular accidents during induction therapy. Cumulative thromboembolism-free survival was significantly reduced in children in the PRED group (thrombosis frequency, 10.4%) compared with children in the DEXA group (thrombosis frequency, 1.8%; P ‫؍‬ .028). Although no significant difference was found in the overall prevalence of prothrombotic risk factors, 46.5% of patients in the PRED group who experienced thromboembolic events were carriers of a prothrombotic risk factor, whereas no carrier in the DEXA group had a thromboembolism. At the time of maximum CASP activity, fibrinogen and activities of antithrombin, plasminogen, and protein S were significantly reduced in the PRED group. No significant correlation could be found between CASP activity and levels of coagulation factors. In conclusion, the use of dexamethasone instead of prednisone, administered with CASP, significantly reduced the onset of venous thromboembolism. (Blood. 2003;101:2529-2533)

The reported incidence of thromboembolism in children with acute lymphoblastic leukemia (ALL) treated with L-asparaginase, vincristine, and prednisone varies from 2.4% to 11.5%. The present study was designed to prospectively evaluate the role of the TT677 methylenetetrahydrofolate reductase (MTHFR) genotype, the prothrombin G20210A mutation, the factor V G1691A mutation, deficiencies of protein C, protein S, antithrombin, and increased lipoprotein (a) concentrations in leukemic children treated according to the ALL-Berlin-Frankfurt-Muenster (BFM) 90/95 study protocols with respect to the onset of vascular events. Three hundred and one consecutive leukemic children were enrolled in this study. Fifty-five of these 301 subjects investigated had one established single prothrombotic risk factor: 20 children showed the TT677 MTHFR genotype; 5 showed the heterozygous prothrombin G20210A variant; 11 were carriers of the factor V G1691A mutation (heterozygous, n = 10; homozygous, n = 1); 4 showed familial protein C, 4 protein S, and 2 antithrombin type I deficiency; 9 patients were suffering from familially increased lipoprotein (a) [Lp(a)] concentrations (>30 mg/dL). In addition, combined prothrombotic defects were found in a further 10 patients: the FV mutation was combined with the prothrombin G20210A variant (n = 1), increased Lp(a) (n = 3), protein C deficiency (n = 1), and homozygosity for the C677T MTHFR gene mutation (n = 1). Lp(a) was combined with protein C deficiency (n = 2) and the MTHFR TT 677 genotype (n = 2). Two hundred eighty-nine of the 301 patients were available for thrombosis-free survival analysis. In 32 (11%) of these 289 patients venous thromboembolism occurred. The overall thrombosis-free survival in patients with at least one prothrombotic defect was significantly reduced compared with patients without a prothrombotic defect within the hemostatic system (P < .0001). In addition, a clear-cut positive correlation (P < .0001) was found between thrombosis and the use of central lines. However, because the prothrombotic defects diagnosed in the total childhood population studied were all found within the prevalences reported for healthy Caucasian individuals, the interaction between prothrombotic risk factors, ALL treatment, and further environmental factors is likely to cause thrombotic manifestations.

The factor V (FV) G1691A mutation, the prothrombin (PT) G20210A variant, the methylenetetrahydrofolate reductase (MTHFR) T677T genotype, together with fasting homocysteine (HCY) concentration, lipoprotein (Lp)(a), anti‐thrombin (AT), protein C (PC), protein S (PS) and anti‐cardiolipin antibodies were investigated in 65 consecutively recruited infants (neonate to < 12 months) with renal venous thrombosis (RVT; n = 31), portal vein thrombosis (PVT; n = 24) or hepatic vein thrombosis (HVT n = 10), and 100 age‐ and sex‐matched healthy controls. FV G1691A was found in 14 babies (heterozygous: RVT n = 9, PVT n = 4; homozygous HVT n = 1) and five controls, the MTHFR TT677 genotype together with increased HCY in four infants with thrombosis (RVT n = 2; PVT n = 1; HVT n = 1) compared with one control, and the PT G20210A variant was present in one control only. PC type I deficiency was diagnosed in three patients (RVT n = 2; PVT n = 1) and AT deficiency in two patients (RVT n = 1; PVT n = 1). Three neonates with spontaneous thrombosis showed FV G1691A combined with Lp(a) and the FV G1691A was combined with the PT G20210A genotype in two infants. Additional triggering factors were reported in 27 patients (41·5%). The overall odds ratios (ORs) and 95% confidence intervals (CIs) with respect to the different thrombosis locations were: RVT (OR/CI: 10·9/3·85–31·1; P < 0·0001), PVT (5·47/1·7–17·6; P < 0·0007) and HVT (3·3/0·58–18·7; P = 0·18). The data presented here suggest that genetic prothrombotic risk factors also play an important role in abdominal venous thrombosis during infancy.

Objective-To evaluate the role of factor (F) VIII in children with non-cancer related venous thrombosis (DVT), post-thrombotic syndrome (PTS) or recurrent DVT. Methods and Results-FVIII levels were measured in White patients and age-and gender-matched healthy controls.Heritability of factor VIII was estimated in 99 pedigrees by the variance component method implemented in SOLAR. Key Words: factor VIII and children Ⅲ body mass index Ⅲ venous thrombosis Ⅲ post-thrombotic syndrome Ⅲ recurrent thrombosis