The plasminogen activator inhibitor (PAI)-1 promoter 4G/4G genotype is not associated with ischemic stroke in a population of German children. Childhood Stroke Study Group

The Genetic Basis of Strokes in Pediatric Populations and Insight into New Therapeutic Options

Strokes within pediatric populations are considered to be the 10th leading cause of death in the United States of America, with over half of such events occurring in children younger than one year of life. The multifactorial etiopathology that has an influence on stroke development and occurrence signify the importance of the timely recognition of both modifiable and non-modifiable factors for adequate diagnostic and treatment approaches. The early recognition of a stroke and stroke risk in children has the potential to advance the application of neuroprotective, thrombolytic, and antithrombotic interventions and rehabilitation strategies to the earliest possible timepoints after the onset of a stroke, improving the outcomes and quality of life for affected children and their families. The recent development of molecular genetic methods has greatly facilitated the analysis and diagnosis of single-gene disorders. In this review, the most significant single gene disorders associated with pediatric stroke are presented, along with specific therapeutic options whenever they exist. Besides monogenic disorders that may present with stroke as a first symptom, genetic polymorphisms may contribute to the risk of pediatric and perinatal stroke. The most frequently studied genetic risk factors are several common polymorphisms in genes associated with thrombophilia; these genes code for proteins that are part of the coagulation cascade, fibrolysis, homocystein metabolism, lipid metabolism, or platelets. Single polymorphism frequencies may not be sufficient to completely explain the stroke causality and an analysis of several genotype combinations is a more promising approach. The recent steps forward in our understanding of the disorders underlying strokes has given us a next generation of therapeutics and therapeutic targets by which to improve stroke survival, protect or rebuild neuronal connections in the brain, and enhance neural function. Advances in DNA sequencing and the development of new tools to correct human gene mutations have brought genetic analysis and gene therapy into the focus of investigations for new therapeutic options for stroke patients.

Association of SERPINE1 rs1799889 polymorphism with arterial ischemic stroke in children: a systematic review and meta-analysis

Inherited thrombophilias are well-established predisposing factors for venous thromboembolism, but their role in arterial ischemic stroke (AIS) in children, remains unclear. The association between SERPINE1 rs1799889 polymorphism and AIS in children was evaluated by several studies, whereas the results were conflicting. Thus, we performed this meta-analysis to combine and analyze the available studies in order to provide a more accurate result on the association. PubMed, Scopus, EMBASE, SciELO, MedRxiv, China Biology Medicine Disk, DeepDyve, CNKI, and Web of Science were used to identify all relevant articles published up to 30 November 2020, without any restrictions on ethnicity. Summary odds ratios (ORs) with 95% confidence intervals (CIs) were used to determine the strength of the associations. A total of eight case-control studies with 600 cases and 2,156 controls were selected. No significant association between SERPINE1 rs1799889 polymorphism and AIS in children susceptibility was noted. In the stratified analyses by ethnicity, source of controls, genotyping methods, and age groups, there was still no significant association between SERPINE1 rs1799889 polymorphism and AIS risk in children. This study suggested that SERPINE1 rs1799889 polymorphism might be not related to etiology of AIS in children. Moreover, well-designed, large-scale and multicenter clinical studies are required to improve and validate these results.Supplemental data for this article is available online at https://doi.org/10.1080/15257770.2021.1966798 .

The Impact of Sex on Arterial Ischemic Stroke in Young Patients: From Stroke Occurrence to Poststroke Consequences

The male sex has been suggested to predominate in paediatric patients with arterial ischemic stroke (AIS), especially in newborns. The explanation for this phenomenon remains unsatisfactory since it focuses on the analysis of the potential relationship with trauma and arterial dissection. In turn, in some populations of young adults, men suffer from AIS more frequently than women, which may be related to the protective role of oestrogen. On the other hand, certain data indicate that women dominate over men. Some of the disparities in the frequencies of particular symptoms of AIS and poststroke consequences in both children and young adults have been suggested; however, data are scarce. Unfortunately, the low number of studies on the subject does not allow certain conclusions to be drawn. For adults, more data are available for patients aged over 60 years, the results of which are more obvious. The present literature review aimed to discuss available data on the prevalence of AIS, its clinical presentations, and poststroke consequences in regard to the sex of young patients. We considered young patients to be children from birth up to the age of 19 years of life and young adults to be individuals up to the age of 55 years. The role of sex hormones in AIS and possible gender differences in genetic risk factors for AIS were also discussed briefly.

Association of PAI-1 rs1799889 Polymorphism with Susceptibility to Ischemic Stroke: a Huge Meta-Analysis based on 44 Studies

BACKGROUND

the PAI-1 rs1799889 polymorphism has been reported to be associated with susceptibility to ischemic stroke. However, the results of previous studies have been inconsistent or controversial. Hence, we performed a systematic review and meta-analysis to evaluate the association of PAI-1 rs1799889 polymorphism with ischemic stroke risk.

METHODS

A comprehensive literature search was performed on PubMed, Web of Science, Scopus, SciELO, CNKI, and CBD databases up to November 05, 2019. Pooled odds ratio (OR) with 95% confidence interval (CI) were used to access the strength of this association in fixed- or random-effects model.

RESULTS

A total of 44 case-control studies with 8,620 cases and 10,260 controls were selected. Pooled data showed a significant association between PAI-1 rs1799889 polymorphism and ischemic stroke risk in the overall populations (GG vs. AA: OR = 0.791, 95% CI 0.633-0.988, p = 0.039; GA vs. AA: OR = 0.807, 95% CI 0.683-0.953, p = 0.012; and GG+GA vs. AA: OR = 0.795, 95% CI 0.637-0.993, p = 0.043). Subgroup analysis by ethnicity revealed a significant association in Asian and Mixed populations, but not in Caucasians. Moreover, stratified analysis by country of origin revealed an increased risk of ischemic stroke in Chinese populations, but not among Dutch (Netherlands) and Swedish.

CONCLUSIONS

This meta-analysis result suggested that PAI-1 rs1799889 polymorphism was associated with an increased risk of ischemic stroke, especially in Asian and Mixed populations.

Lack of Associations Between PAI-1 and FXIII Polymorphisms and Arterial Ischemic Stroke in Children: A Systematic Review and Meta-Analysis

The role of genetic risk factors for ischemic stroke seems to be in particular significance in pediatric patients. Numerous polymorphic variants of genes encoding proteins, that is, plasminogen activator inhibitor as well as coagulation factors, involved in the coagulation cascade may be related to arterial ischemic stroke (AIS) both in adults and children. We performed systematic review and 2 meta-analyses to assess possible correlations between common plasminogen activator inhibitor (PAI-1) and FXIII polymorphisms and ischemic stroke in children. We searched PubMed to identify available data published before October 2018 using appropriate keywords and inclusion criteria. Finally, 12 case-control studies were included: 8 analyzing PAI-1 polymorphism (600 children with stroke and 2152 controls) and 4-FXIII polymorphism (358 children with stroke and 451 controls). R and Comprehensive Meta-Analysis software were used to analyze the impact of the particular polymorphism in the following models: dominant, recessive, additive, and allelic. No publication bias was observed in both meta-analyses. In case of PAI-1 polymorphism, we observed no relation between 4G4G genotype of 4G allele and ischemic stroke in children. We also demonstrated lack of association between FXIII polymorphism and childhood ischemic stroke. In children with AIS, the PAI-1 and FXIII polymorphisms are not risk factors for the disease.

Thrombophilia risk is not increased in children after perinatal stroke

Thrombophilia in children with perinatal stroke is rare, with rates similar to those in the normal population. Routine testing in childhood is not indicated.

Association of Polymorphisms in Coagulation Factor Genes and Enzymes of Homocysteine Metabolism With Arterial Ischemic Stroke in Children

Despite the identification of a wide range of inherited and acquired risk factors for arterial ischemic stroke (AIS) in children, genetic risk factors are incompletely characterized and may vary among different populations. We investigated the role of individual and combined inherited prothrombotic and intermediate-risk factors in 73 children with perinatal (n = 35) and childhood AIS (n = 38) and 100 age- and sex-matched controls. Ten polymorphisms in 8 candidate genes encoding coagulation and fibrinolytic proteins (factor V [FV] Leiden, FV HR2, factor II [FII] G20210A, β-fibrinogen [β-FBG]-455G>A, factor XIII [FXIII]-A p.Val34Leu, plasminogen activator inhibitor 1 4G/5G), homocysteine metabolism (methylenetetrahydrofolate reductase [MTHFR] C677T, MTHFR A1298C), and intermediate-risk factors (angiotensin-converting enzyme I/D, apoE ∊2-4) were detected using a multilocus genotyping assay. Allele-specific polymerase chain reaction was used for the determination of human platelet alloantigens (HPA-1, HPA-2, HPA-3, and HPA-5). Factor V Leiden was associated with an increased risk of AIS (odds ratio [OR]: 4.72, 95% confidence interval [CI]: 1.22-18.27) and perinatal AIS (OR: 8.29, 95% CI: 1.95-35.24). Human platelet antigen-3b allele carriers had a 2-fold lower risk of AIS (OR: 0.51, 95% CI: 0.26-0.98) and perinatal AIS (OR: 0.40, 95% CI: 0.18-0.92). A 2.21-fold increased risk of childhood AIS (95% CI: 1.03-4.73) was identified in FXIII-A Leu34 allele carriers. Combined FV Leiden/FV HR2, FV Leiden/MTHFR A1298C, FV Leiden/MTHFR C677T/MTHFR A1298C, and FV Leiden/FV HR2/MTHFR A1298C heterozygosity was identified in children with AIS but not in controls, which revealed a statistically significant difference. This case-control study shows that besides already documented association between FV Leiden and AIS, other previously unreported polymorphisms (FXIII-A p.Val34Leu, HPA-3) and several genotype combinations that always include heterozygous FV Leiden can be related to AIS in Croatian population.

Significance of Factor V, Prothrombin, MTHFR, and PAI-1 Genotypes in Childhood Cerebral Thrombosis

The aim of this study was to evaluate the significance of factor V (FV) G1691A, prothrombin G20210A, methylenetetrahydrofolate reductase (MTHFR) C677T, and plasminogen activator inhibitor-1 (PAI-1) 4G/5G genotypes in development of childhood cerebral thrombosis (CT). A total of 113 Turkish children with CT were studied and compared with the control group. The carrier frequency of the factor V G1691A mutation was found to be significantly higher in the patient group (17.7%) than controls (7.4%). The presence of this genotype was associated with a 2.7-fold increased risk of developing CT (95% confidence interval [CI], 1.0—7.0). The prevalence of prothrombin G20210A mutation in 110 patients (4.5%) was insignificantly higher than controls (2.3%) (odds ratio, 2.0; 95% CI, 0.4—10.7). A statistically significant increase in the frequency of homozygous MTHFR C677T genotype was observed in 62 patients (11.3%) compared to controls (4.3%), and this genotype was associated with 2.8-fold increased CT risk (95% CI, 1.0—8.0). The incidence of PAI-1 4G/4G genotype in 65 patients (21.5%) was slightly lower than that of controls (26.0%), but the differences did not reach statistical significance (odds ratio, 0.8; 95% CI, 0.4—1.5). The results of this study suggested that factor V G1691A and MTHFR C677T genotypes may be associated with an increased risk of developing CT in Turkish children.

Association Between Plasminogen Activator Inhibitor-1 Genetic Polymorphisms and Stroke Susceptibility

The plasminogen activator inhibitor-1 (PAI-1) is a candidate gene for stroke based on PAI-1's crucial role in fibrinolytic system. However, association studies have yielded conflicting results regarding the association between PAI-1 polymorphisms and stroke susceptibility. To further elucidate the putative association, we performed a systematic review and meta-analysis to provide a complete picture of the loci investigated for association of PAI-1 polymorphism with stroke risk and to derive a precise estimation. PubMed, Embase, and China National Knowledge Infrastructure (CNKI) databases were searched until June 2015 to identify eligible studies. Forty data sets from 39 studies with a total of 8336 cases and 14,403 controls were included. The most commonly investigated polymorphism was -675 4G/5G, followed by -844 G/A, 11053 T>G, HindIII C/G, and (CA)n. Overall, our meta-analysis provided evidence for the significant association of PAI-1 4G/5G polymorphism with an increased risk of adult but not pediatric ischemic stroke (adult: 4G/4G vs. 4G/5G + 5G/5G, OR = 1.21, 95 % CI = 1.04-1.42). In the subgroup analysis, significant association was detected in Asians (4G/4G vs. 4G/5G + 5G/5G, OR = 1.45, 95 % CI = 1.14-1.85) but not Caucasians. Moreover, we found that -844 G/A but not 11053 T>G polymorphism was associated with an increased risk of ischemic stroke (-844G/A: A/A vs. G/G: OR = 1.32, 95 % CI = 1.01-1.73). A tendency of PAI-1 4G/5G polymorphism towards a decreased risk of hemorrhagic stroke was observed (4G/4G + 4G/5G vs. 5G/5G, OR = 0.77, 95 % CI = 0.59-1.02, P = 0.066). Future well-designed studies in large well-characterized sample size and presenting results stratified by gender, age, and stroke subtype are warranted.

Global fibrinolytic activity, PAI-1 level, and 4G/5G polymorphism in Thai children with arterial ischemic stroke

BACKGROUND

Prolonged euglobulin clot lysis time (ECLT) and increased level of plasminogen activator inhibitor-1 (PAI-1) were reported to be risk factors of arterial ischemic stroke (AIS) by some studies; however, these findings were not supported by other studies. The objective of this study was to determine the association of ECLT, PAI-1 level, and polymorphisms of 4G and 5G of PAI-1 gene to the development of AIS in Thai children.

METHODS

This study included patients aged 1-18 years old. Diagnosis of AIS was confirmed by imaging study. The control group was age- and sex-matched healthy subjects. Demographic data were recorded, and blood was tested for ECLT, PAI-1 level, lipid profiles, fasting blood sugar (FBS), and 4G and 5G polymorphisms of PAI-1 gene.

RESULTS

There were 70 subjects participating in this study, consisting of 30 patients and 40 controls. Demographic data, lipid profiles, and FBS were similar between the 2 groups. Furthermore, ECLT and PAI-1 level did not differ between patient and control groups; however, both showed significant correlation (r = .352, P = .006). The 4G/5G polymorphism was the most common genotype in both patient and control groups (69.0% vs. 80.0%). However, 4G and 5G polymorphisms of PAI-1 gene did not correlate with PAI-1 level in this study (P = .797).

CONCLUSIONS

The PAI-1 level and 4G/5G polymorphism may not be a risk factor of AIS in this population. It was also found that the 4G/5G polymorphism was the most common PAI-1 genotype in this study.

Advances in understanding stroke risk in children--a geneticist's view

The advent of the genomic era has provided novel insights into the genetic architecture of common complex diseases, such as thrombophilia and stroke. Since 2006, a growing number of genome wide association studies (GWAS) for common complex diseases have revealed new candidate loci and genomic regions that play an important role in disease aetiology and progression. While GWAS on the above mentioned traits are abundant in adults, similar studies in paediatric study cohorts are lagging behind. However, genetic research in this important clinical area has gained momentum and starts to provide us with exciting insights into the genetic underpinnings of stroke with paediatric onset. Here we review recent advances in genetic association studies underlying stroke in children and aim to translate the results to clinical utility. These studies comprise candidate gene approaches and GWAS, and represent the current status on what we have learnt about the genetic architecture underlying paediatric stroke, and how this may affect medical practice in the years to come.

Inherited prothrombotic risk factors in children with first ischemic stroke

Stroke in children is a heterogeneous disorder. Over 100 risk factors for stroke have been reported and genetic predisposition to stroke has been established. The most frequently reported risk factors are congenital heart malformations, hemolytic anemias, collagen vascular diseases, some rare inborn metabolic disorders, trauma, infection and thrombophilia. The aim of this article is to provide an overview of investigated inherited prothrombotic risk factors in children with first ischemic stroke. Various prothrombotic risk factors have been investigated in pediatric stroke including elevated homocysteine and lipoprotein (a), antithrombin, protein C and protein S deficiency, Factor V Leiden, Factor II G20210A and plasminogen activator inhibitor-1 4G/5G polymorphism. Despite similar criteria for inclusion of different studies in meta-analyses investigating first ischemic stroke in children, the obtained results were not consistent for all prothrombotic risk factors. The discrepancies found could be explained by methodological issues like different sample sizes, patient populations included and lack of controls. In order to provide the necessary power for randomized control trials, multi-center, multi-national approaches like International Pediatric Stroke Study have been initiated with the aim to describe risk factors for childhood stroke and explore their relationship with presentation, age, geography, and infarct characteristics. Although it is evident from numerous studies that the frequency of inherited prothrombotic factors is increased in pediatric stroke, single thrombophilia does not fully explain stroke in a child as it represents only a mild risk factor. Further studies are needed, as improved understanding of underlying mechanisms will improve primary and secondary prevention of childhood stroke.

The black box of perinatal ischemic stroke pathogenesis

An improved understanding of perinatal stroke epidemiology, classification, neuroimaging, and outcomes has emerged in recent years. Despite this, little is known regarding the pathophysiological mechanisms responsible for most cases. A multitude of possible associations and putative risk factors have been reported, but most lack definitive empirical evidence supporting primary causation. These include obstetrical and maternal factors, perinatal conditions, infectious diseases, prothrombotic abnormalities, cardiac disorders, medications, and many others. The bulk of evidence is weak, dominated by case reports and retrospective case series. Findings from the small number of case-control and cohort studies that exist are limited by heterogeneous populations and methodologies. The single largest barrier to ultimately understanding and potentially improving outcomes from this common and disabling condition is the lack of comprehensive, fully powered risk factor studies required to definitively describe perinatal stroke pathogenesis. This review summarizes current evidence and suggests future directions for research.

Use of intravenous tissue plasminogen activator in a 16-year-old patient with basilar occlusion

Intravenous tissue plasminogen activator (t-PA) is currently approved by the US Food and Drug Administration (FDA) for the treatment of ischemic stroke in patients > 18 years of age who present within 3 hours of stroke onset and meet certain criteria. We report a case of a 16-year-old, previously healthy female who presented with a basilar artery occlusion and pontine ischemic stroke. She was treated with intravenous t-PA approximately 4 hours after the onset of symptoms. The patient demonstrated a remarkable recovery 6 hours after onset of her symptoms and had minimal deficits on discharge from the hospital 1 week later. She was found to have a lupus anticoagulant and was heterozygous for the prothrombin gene G2010A mutation. These were likely contributing causes for her stroke. She was also homozygous for plasminogen activator inhibitor 1 (PAI-1) 4G/4G, which at present is a controversial stroke risk factor.

Genetic polymorphisms for the study of multifactorial stroke

Single-gene disorders explain only a minority of stroke cases. Stroke represents a complex trait, which is usually assumed to be polygenic. On this topic, the role of a wide number of candidate genes has been investigated in stroke through association studies, with controversial results. Therefore, it is difficult for the clinician to establish the validity and the level of clinical applicability of the previously reported associations between genetic factors and stroke. This review is an update and an extensive analysis of the more recent association studies conducted in stroke. We evaluated a number of studies on several candidate genes (including F5, F2, FGA/FGB/FGG, F7, F13A1, vWF, F12, SERPINE1, ITGB3/PLA1/PLA2/ITGA2B, ITGA2, GP1BA, ACE, AGT, NOS3, APOE, LPL, PON1, PDE4D, ALOX5AP, MTHFR, MTR, and CBS), providing a final panel of genes and molecular variants. We categorized this panel in relation to the degree of association with stroke, supported by the results of meta-analyses and case-control studies. Our findings could represent a useful tool to address further molecular investigations and to realize more detailed meta-analyses.

Plasminogen activator inhibitor-1 4G/5G polymorphism and risk of ischemic stroke: a meta-analysis

This study investigated the hypothesis that the insertion/deletion (4G/5G) polymorphism of the plasminogen activator inhibitor type-1 gene affects the risk for ischemic stroke, since results concerning this association have been controversial. We therefore performed a meta-analysis of published data regarding this issue. A comprehensive electronic search was carried out until January 2006. The analysis was performed using random-effects models and meta-regression. Eighteen eligible studies were retrieved (15 case-control studies and three cohort studies). The case-control studies included 3104 cases and 4870 control individuals concerning the contrast of 4G/4G versus remaining genotypes. The 4G pooled allele frequencies in cases and controls were 54.21 and 54.75%, respectively. Overall, the per-allele odds ratio of the 4G allele was 0.98 (95% confidence interval, 0.858-1.121). Regarding genotypes, we derived nonsignificant odds ratios in all contrasts. The subanalysis including the three studies with a prospective design in the 4G/4G versus 5G/5G contrast derived a significant result (relative risk, 0.523; 95% confidence interval, 0.353-0.775), but the estimated effect size was insignificant when cohort and case-control studies were analyzed together (relative risk, 0.848; 95% confidence interval, 0.662-1.087). We failed to demonstrate a significant association between the 4G/5G polymorphism and ischemic stroke under basal conditions. Determination of plasminogen activator inhibitor type-1 function seems of much higher clinical value than determination of the 4G/5G polymorphism. The effect of this genotype on risk of ischemic stroke in acute stressful diseases and the role of cohort studies in genetic epidemiology, however, warrant further investigation.

Prothrombotic risk factors in the evaluation and management of perinatal stroke

The ischemia in children affected by perinatal stroke has long been thought to be driven by nonhematologic maternal and perinatal events. New information from clinical studies, however, tells us that plasma-phase risk factors, such as factor V Leiden, elevated lipoprotein (a), and mutations in MTHFR, may be important in the pathogenesis of perinatal stroke, if not always in the risk of recurrence. With regard to stroke recurrence, this risk is only about 2% according to the largest follow-up study to date, and certainly less than 5%. Nonetheless, when strokes do recur, they tend to be associated with the presence of plasma-phase risk factors in the affected child, suggesting that a small percentage of children with a first perinatal stroke may benefit from anticoagulation therapy, both to prevent stroke recurrence as well as occurence of a second, non-CNS thrombotic event. Counselling of parents with regard to subsequent pregnancies should always include medical management of systemic maternal disorders, such as diabetes, persistently elevated antiphospholipid antibodies, and inherited maternal hypercoagulability states.

Risk factors for perinatal arterial stroke: a study of 60 mother-child pairs

The objective of the present study was to examine demographic, historical, and prothrombotic risk factors in infants with perinatal arterial stroke and their mothers. Risk factors were evaluated in 60 mother-child pairs with perinatal arterial stroke. Prothrombotic factors analyzed included the DNA mutations factor V Leiden, prothrombin 20210, MTHFR C677T and A1298C; serum activity levels for protein C, protein S, and antithrombin III; serum levels of lipoprotein(a); and, in the mothers, antiphospholipid antibodies. Boys predominated, 36:24. There were four twin sets. Sixty percent were term and 22% were post-date. Ten were large for gestational age. Five mothers had abdominal trauma. Nine mothers (15%) had preeclampsia. Emergency caesarean section was performed in 17 cases (28%). Eight placental exams revealed seven with abnormalities. Seizures were the presenting sign in 70%, and 30% presented with early handedness or cerebral palsy. Prothrombotic risk factors were found in 28 of 51 mothers (55%) and 30 of 60 children (50%). Forty-one pairs (68%) had at least one abnormality in mother, child, or both. Long-term sequelae included cerebral palsy (40 of 51; 78%), cognitive impairment (35 of 51; 68%), seizures (23 of 51; 45%), and microcephaly (26 of 51; 51%). Perinatal arterial stroke is the result of multifactorial, synergistic fetal and maternal factors among which the prothrombotic factors, both fetal and maternal, appear significant.

Prothrombotic factors in children with stroke or porencephaly

OBJECTIVE

This study compared the frequencies of genetic and functional coagulation abnormalities in children with arterial ischemic stroke or porencephaly with frequencies in previously published studies.

METHODS

A series of 59 children (age 0-18 years) with arterial ischemic stroke or porencephaly were referred to the National Institutes of Health. A blood sample, buccal smear sample, questionnaire, and pedigree were requested for each child. Blood samples were analyzed for protein C (PC); protein S; antithrombin (AT); activated PC resistance (APCR); lipoprotein (a) [Lp(a)]; lupus anticoagulant; anticardiolipin antibodies; and the methylenetetrahydrofolate reductase C677T (MTHFR), factor V G1619A, factor II G20210A (PT), plasminogen activator inhibitor-1 4G6755G, and tissue factor pathway inhibitor C536T mutations. The frequency of each coagulation abnormality was compared with published international pediatric stroke case and control rates.

RESULTS

At least 1 prothrombotic abnormality was identified in 63% (36 of 57) of children studied, including plasminogen activator inhibitor-1 4G6755G (15 of 56), MTHFR (12 of 56), elevated Lp(a) (12 of 59), APCR (11 of 58), factor V G1619A (5 of 57), PT (3 of 57), PC deficiency (1 of 59), and AT deficiency (1 of 59). The MTHFR mutation, elevated Lp(a), the PT mutation, and AT deficiency rates were similar to rates in cases and more common than control subjects in previously published studies. The rate of children with APCR or multiple abnormalities was higher than in previous pediatric stroke studies. A family history of early thrombosis was identified in one third of the children with a prothrombotic abnormality.

CONCLUSIONS

Two thirds of children in this study had at least 1 of the prothrombotic risk factors tested, and several children had multiple risk factors. These results provide additional evidence that prothrombotic abnormalities are common among children with AIS or porencephaly.

Prothrombotic abnormalities in childhood ischaemic stroke

Childhood ischaemic stroke, incorporating arterial ischaemic stroke and cerebral sinus venous thrombosis, is associated with significant morbidity and mortality in children. The majority of cases in children present with well-recognised risk factors. The appreciation of the role prothrombotic abnormalities have in disease states is developing rapidly. Prothrombotic abnormalities are abnormalities of the coagulation system, fibrinolytic system, endothelial cells or platelets that lead to a reduced threshold for pathological thrombus formation. Our understanding of the role of prothrombotic abnormalities in childhood ischaemic stroke is increasing and has a direct bearing on the development of effective management and prevention strategies. We provide a brief background of prothrombotic abnormalities and review the available literature on prothrombotic markers in childhood ischaemic stroke. Overall, prothrombotic abnormalities have been identified in 20-50% of children presenting with AIS and 33-99% of children with cerebral sinus venous thrombosis. There appear to be a number of associations emerging including an increased frequency of factor V Leiden mutation, elevated lipoprotein (a), protein C deficiency and antiphospholipid antibodies in children presenting with arterial ischaemic stroke. The pathogenic role of prothrombotic abnormalities as predisposing to initial and recurrent childhood ischaemic stroke is becoming increasingly evident. The impact on treatment, however, will only be clarified with carefully designed, multi-institutional prospective studies.

Thrombophilia and first arterial ischaemic stroke: a systematic review

AIMS

To undertake a systematic review of the literature reporting the prevalence of thrombophilia in children with a first arterial ischaemic stroke (AIS).

METHODS

Systematic review of case-control studies reporting data for prevalence of protein C, S, and antithrombin (AT) deficiencies, activated protein C resistance (APCr), total plasma homocysteine >95th centile, the thrombophilic mutations factor V1691 GA, prothrombin 20210GA, and MTHFR C677T in children with first, radiologically confirmed, AIS.

RESULTS

Of 1437 potentially relevant citations, 18 met inclusion criteria. A total of 3235 patients and 9019 controls had been studied. Results of meta-analyses were expressed as pooled odds ratios (OR) relating the prevalence of the thrombophilic condition in children with AIS to that in controls. The pooled OR (and 95% CI) were: protein C deficiency, 6.49 (2.96 to 14.27); protein S deficiency, 1.14 (0.34 to 3.80); AT deficiency, 1.02 (0.28 to 3.67); APCr, 1.34 (0.16 to 11.52); FV1691 GA, 1.22 (0.80 to 1.87); PT20210GA, 1.10 (0.51 to 2.34); MTHFR C677T, 1.70 (1.23 to 2.34); and total plasma homocysteine >95th centile, 1.36 (0.53 to 3.51). There was no statistical heterogeneity within these data.

CONCLUSIONS

All factors examined were more common in children with first AIS than in controls, and significantly so for protein C deficiency and the MTHFR C677T mutation. The implications of thrombophilia for prognosis and recurrence need to be established before clinical recommendations can be made regarding investigation and treatment of children with AIS.

Genotype and allele frequency of PAI-1 promoter polymorphism in healthy subjects from the west of Mexico. Association with biochemical and hematological parameters

We investigated the genotype and allelic frequency of the -675 bp insertion/deletion polymorphism at the PAI-1 gene promoter, in healthy Mexican subjects. It was compared to the lipid profile and hematological parameters, and to other healthy worldwide populations. A Mexican population sample of 110 individuals was studied. Demographic data and clinical characteristics of the subjects were registered. Fasting lipid profile, serum glucose, fibrinogen, hematological parameters and leukocyte genomic DNA isolation from peripheral blood were performed in all the participants. Screening of the PAI-1 genotype was done by PCR and restriction analysis. Genotype 4G/4G, 4G/5G, 5G/5G frequency in Mexican healthy subjects was: 14.55%, 39.09%, 46.36%, respectively, whereas the allelic frequency for 5G allele was 65.9%. A significant lesser frequency for 4G allele and related genotypes (4G/4G and 4G/5G) was established in healthy subjects from Mexico, respect to all the compared populations. A particular genotype and allelic frequency of this PAI-1 polymorphism was established in Mexico. The clinical parameters were not associated according to each genotype of PAI-1.

Is there a genetic basis for pediatric stroke?

PURPOSE OF REVIEW Childhood: stroke is more common than brain tumor, but because there is a wide spectrum in terms of etiology and most centers see only a few cases every year, there have been few large studies of genetic and environmental risk factors until recently. This review focuses on the clinical and radiologic methodology required to distinguish phenotypes in patients, and it focuses on the available data on genetic predisposition.

RECENT FINDINGS

A number of conditions with Mendelian inheritance (eg, sickle cell disease) predispose to childhood stroke, but the search for epistatic polymorphisms that explain why some but not all of these patients are affected has been hampered by our poor understanding of the pathophysiology. Emergency vascular imaging, including arteriography and venography, will almost certainly assist with the description of stroke subtypes with different genetic predisposition in these patients and in the important group of children who were completely healthy before their stroke. Environmental exposure (eg, to infection, hypoxemia, and vitamins) may play a crucial role in modifying genetic expression and must be described carefully in prospective studies.

SUMMARY

Now that much of the work on classifying stroke subtypes in children has been undertaken, international collaboration is likely to lead to identification of the genetic and environmental risk factors, and thus to primary and secondary prevention.

Arterial ischemic stroke in childhood: the role of plasma-phase risk factors

The role of plasma-phase risk factors for stroke in the pediatric age group is presently unclear due to the lack of sufficiently large prospective studies, and due to the fact that these risk factors do not apply uniformly to newborns, children with sickle cell disease, and older children. Available evidence indicates that factor V Leiden, prothrombin 20210A, and lipoprotein (a) are all important in the pathogenesis of arterial ischemic stroke in older children, but the role of other plasma-phase risk factors remains uncertain. The contribution of these risk factors to newborn stroke and the stroke of children with sickle cell disease is similarly unclear, likely because the ischemia in affected children is predominantly due to nonhematologic perinatal events and erythrocyte adhesion to endothelium with obstruction of flow in the cerebral microcirculation, respectively. Evaluation of childhood stroke should, in our view, always be performed from the standpoint of the presenting clinical symptoms, diagnostic imaging, and determination of plasma-phase risk factors. Therapeutic anticoagulation and use of antiplatelet agents at present focus on the older child.