Prothrombotic polymorphisms, mutations, and their association with pediatric non-cardioembolic stroke in Asian-Indian patients

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.

MTHFR A1298C gene polymorphism on stroke risk: an updated meta-analysis

Background

Previous studies have shown the effect of MTHFR A1298C gene polymorphism on stroke risk. But the results of published studies remained inconclusive and controversial. So we conducted a meta-analysis to accurately estimate the potential association between MTHFR A1298C gene polymorphism and stroke susceptibility.

Methods

A systematic literature search on Embase, Pubmed, Web of Science, Cochrane Library, China National Knowledge Infrastructure (CNKI) and WanFang electronic database identified 40 articles including 5725 cases and 8655 controls. Strength of association was evaluated by pooled odds ratio (OR), 95% confidence interval (CI) and p value. Funnel plots and Begger’s regression test were applied for testing the publication bias. Statistical analysis of all data was performed by Stata 12.0.

Results

The meta-analysis results indicated a significant relationship between MTHFR gene A1298C polymorphisms and stoke risk under the C allelic genetic model (OR = 1.19, 95%CI = 1.07–1.32, p = 0.001), dominant genetic model (OR = 1.19, 95%CI = 1.06–1.33, p = 0.004) and recessive genetic model (OR = 1.43, 95%CI =1.15–1.77, p = 0.001). In subgroup analysis, we discovered obvious correlation in three genetic model of Asian, stroke type, adult by ethnicity, population, stroke type, source of control and case size. Additionally, in studies of control from hospital and case size equal 100, obvious correlation was also found in the three genetic model.

Conclusions

Our meta-analysis results indicated that there was evidence to support the correlation between MTHFR A1298C polymorphism and stroke susceptibility, especially in adults and ischemic stroke.

Relationship between methylenetetrahydrofolate reductase (MTHFR) gene (A1298C) polymorphism with the risk of stroke: A systematic review and meta-analysis

Studies on relationship between methylenetetrahydrofolate reductase gene (MTHFR) gene A1298C polymorphism with the risk of ischemic as well as hemorrhagic stroke have shown discordant results. Present meta-analysis was aimed to clarify the relationship between MTHFR gene A1298C polymorphism with risk of stroke. A comprehensive literature search for all published articles was performed in electronic database including PubMed, EMbase, Cochrane Library, Trip Databases, Worldwide Science, CINAHL, and Google Scholar up to 31st  December 2019. Pooled odds ratio (ORs) with 95% confidence interval (CIs) under dominant, recessive, and allelic models was calculated. Sensitivity analysis was also performed to detect the heterogeneity. In our meta-analysis, a total of 20 studies with 19 case control studies involving 2871 ischemic stroke (IS) cases and 3984 controls and 3 studies with 201 hemorrhagic stroke cases and 1349 controls were included. Our findings suggest that there was a significant relationship between MTHFR gene A1298C gene polymorphism with risk of ischemic stroke (dominant model: OR = 1.32, 95% CI = 1.06-1.66, recessive model: OR = 1.45, 95% CI = 1.06-1.99 and allelic model: OR = 1.35, 95% CI = 1.00-1.84, respectively). However, no significant relationship between MTHFR gene A1298C gene polymorphism with the risk of hemorrhagic stroke. Findings of this meta-analysis concludes that MTHFR gene A1298 C polymorphism could be capable of increasing stroke susceptibility in Asian, but not in Caucasian population. Genotyping of MTHFR gene A1298C polymorphism may be used as a predictor for the occurrence of ischemic stroke.

Is the 1298A>C polymorphism in the MTHFR gene a risk factor for arterial ischaemic stroke in children? The results of meta-analysis

An elevated level of homocysteine is a risk factor for vascular diseases, brain atrophy and several other disorders. The 1298A>C polymorphism (rs1801131) leads to mildly decreased MTHFR activity. Previously, it was observed that the MTHFR 1298A>C polymorphism in combined analysis with the MTHFR 677C>T polymorphism increases homocysteine levels. However, conflicting results on its relation to ischaemic stroke in children can be found. We conducted a meta-analysis to analyse possible connections between the MTHFR 1298A>C polymorphism and ischaemic stroke in paediatric patients. We identified available data published before December 2016 using appropriate keywords and searching PubMed as well as the references cited in the found articles. Eight case-control studies were included in the meta-analysis (426 children with stroke and 778 controls). Statistical analyses were made using R and Comprehensive Meta-Analysis softwares to investigate the impact of polymorphism in four models: dominant, recessive, additive and allelic. No publication bias was observed in the meta-analysis. We demonstrated no relationship between the 1298A>C polymorphism and ischaemic stroke in children in the case of recessive, additive and allelic models. However, the results of the dominant model analysis should be treated with caution due to the sensitivity analysis results. After omitting one of the included study, we observed a significant association between the carriers of the MTHFR C allele (cases with AC + CC genotypes) and ischaemic stroke in children (OR 1.35 95% CI 1.02-1.79, p = 0.035 in a fixed effects model). In conclusion, the 1298A>C polymorphism in the MTHFR gene is not a risk factor for ischaemic stroke in paediatric patients.

An extremely rare complication following frontoorbital advancement: infarction of the recurrent artery of Heubner

Many intracranial as well as extracranial complications can be seen following craniosynostosis surgeries. In this article, we would like to share an extremely rare complication of the infarction of the recurrent artery of Heubner, occurred following frontoorbital advancement. In this case, an 18-month-old male patient underwent supraorbital bar and frontal bone remodeling surgery for nonsyndromic metopic suture synostosis. The preoperative neurosurgical evaluation revealed no signs of increased intracranial pressure. On the 3rd postoperative day, the patient developed asymmetric smile and weakness on the left extremities. Computerized tomography showed a hypodense infarction region around the right basal ganglia and internal capsule, concordant with the region supplied by the recurrent artery of Heubner. The patient's symptoms started to regress on the 2nd day of enoxaparine treatment and he was discharged on 12th postoperative day with almost no signs of the event. In this paper, we presented an unlikely complication after frontoorbital advancement. Keeping in mind the long operating time and the proximity of the procedure to the central nervous system, assessment of the neurological function of the patients both before and after the operation and rapid intervention in case of development of neurologic symptoms are of great importance.

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.

Systematic review: hereditary thrombophilia associated to pediatric strokes and cerebral palsy

OBJECTIVES

This review aimed to organize and consolidate the latest knowledge about mutations and genetic polymorphisms related to hereditary thrombophilia and their potential association with pediatric stroke and cerebral palsy (CP).

SOURCES

Scientific articles published from 1993 to 2013, written in Portuguese, English, French, and Spanish, were selected and reviewed. The publications were searched in electronic databases, and also in the collections of local libraries. The terms "hereditary thrombophilia", "polymorphisms", "mutation", "pediatric strokes", and "cerebral palsy" were used for the research.

SUMMARY OF THE FINDINGS

The search in databases and in the bibliographic references retrieved 75 articles for inclusion in this review. Studies that investigated hereditary thrombophilias and their associations to CP and arterial and venous pediatric stroke presented contradictory results. The meta-analysis and case-control studies that showed positive results for this association described only slightly increased relative risks and sometimes had questionable conclusions. The association of two or more hereditary thrombophilias, or the association between thrombophilia and other specific clinical risk factors, suggest a higher risk of CP and pediatric stroke than isolated hereditary thrombophilia.

CONCLUSIONS

Larger, multicenter studies should be developed in order to elucidate the role of mutations leading to hereditary thrombophilia and the development of CP and pediatric stroke. The complex and multifactorial etiology of CP and stroke makes this an arduous and difficult task; however, the benefits generated by these studies are immeasurable.

Methylenetetrahydrofolate reductase gene A1298C polymorphism in pediatric stroke--case-control and family-based study

Moderate hyperhomocysteinemia is one of the risk factors of pediatric stroke. Methylenetetrahydrofolate reductase (MTHFR) is an important enzyme, which regulates homocysteine metabolism, and some polymorphisms of gene encoding this enzyme are associated with a decreased activity of the enzyme. The aim of the study was to assess an association between the A1298C polymorphism and pediatric stroke. We also evaluated a possible synergistic effect of A1298C and C677T polymorphisms of this gene. The study group consisted of 88 children after ischemic stroke, 142 of their parents and 111 controls. The A1298C polymorphism was genotyped using the restriction fragment length polymorphism method. We used 2 study designs: a case-control model and a family-based association test. The Statistica 7.1 and EpiInfo 6 softwares were used in all analyses. We did not observe any statistically significant differences either in the transmission of the A allele in the family-based test or in the frequency of the A allele in the patients group compared with the controls. We also did not notice any significant additive or synergistic effects between the A1298C and C677T polymorphisms. An analysis of the results obtained in this study and a critical review of previously published studies indicate that the A1298C polymorphism of the MTHFR gene is not related to ischemic stroke in children.

Quantitative assessment of association between rs1801133 polymorphism and susceptibility to stroke

Methylenetetrahydrofolate reductase (MTHFR) is an important enzyme involved in folate metabolism, which is essential for DNA synthesis and methylation. Genetic variations in the MTHFR gene seem to contribute to a decreased activity of MTHFR, ultimately confer increased susceptibility to stroke. To assess the association between this polymorphism and stroke risk, we conducted a comprehensive meta-analysis based on 73 eligible studies. A total of 73 studies, including 10,225 cases and 13,800 controls identified between 1999 and 2012, were selected through researching the PubMed, MEDLINE, EMBASE, Cochrane Library, Web of Science, and Chinese Biomedical Chinese National Knowledge Infrastructure and Literature database databases. Odds ratios (ORs) with corresponding 95% confidence intervals (CIs) were used to assess the association. Overall, a significant elevated risk of stroke risk was associated with the rs1801133 polymorphism in all genetic models (homozygote model: OR 1.296, 95% CI 1.109-1.514; dominant model: OR 1.179, 95% CI 1.058-1.315; recessive model: OR 1.209, 95% CI 1.063-1.375; allele comparison model: OR 1.154, 95% CI 1.061-1.256). In the stratified analyses, significantly increased stroke risks were indicated among Asians in all genetic models (homozygote model: OR 1.726, 95% CI 1.314-2.267; dominant model: OR 1.535, 95% CI 1.282-1.838; recessive model: OR 1.452, 95% CI 1.160-1.818; allele comparison model: OR 1.403, 95% CI 1.211-1.626).The present meta-analysis suggests that rs1801133 polymorphism contributes to the risk of stroke, of note, in Asian populations.

Genetic variations in the thrombin-activatable fibrinolysis inhibitor gene and risk of cardiovascular disease: a systematic review and meta-analysis

BACKGROUND

An imbalance between coagulation and fibrinolytic system plays an important role in the pathogenesis of arterial thrombosis. It has been identified that elevated plasma thrombin-activatable fibrinolysis inhibitor (TAFI) concentration, an anti-fibrinolytic factor, is associated with an increased risk of cardiovascular disease (CVD). But the effect of genetic variations in TAFI gene on the risk of CVD is inconclusive.

OBJECTIVES

To investigate the associations between two variants Ala147Thr(rs3742264) and Thr325Ile(rs1926447) in TAFI and the risk of CVD.

METHODS

Systematic review and meta-analysis of eligible studies published before January 2014. Coronary heart disease(CHD) and stroke are regarded as end-points of CVD.

RESULTS

A total of 18 articles including 23 studies were enrolled. Among these articles were 19 studies of Ala147Thr and 15 of Thr325Ile variants, comprising 4,977 CVD patients and 8,082 controls together with 4,890 cases and 8,311 controls, respectively. There were no significant associations between Ala147Thr variant and CVD under allele, dominant, recessive genetic models. Similar results were observed when end-point, ethnicity, sample size, genotyping method were taken into account. Likewise, meta-analysis of Thr325Ile variant did not show significant associations with CVD under three genetic models. Nevertheless, in sub-analysis based on end-point, the TT(Ile/Ile) genotype was associated with a 25% higher risk of coronary heart disease(CHD) (OR=1.25, 95%CI, 1.02-1.54; P=0.03) compared with TC+CC(Thr/Ile+Thr/Thr) genotype(recessive model).

CONCLUSIONS

The present meta-analysis failed to confirm the influence of Ala147Thr and Thr325Ile variants on the susceptibility to CVD. However, potentially increased risk of CHD was detected in Ile325 allele carriers under recessive model.

The role of genetic risk factors in arterial ischemic stroke in pediatric and adult patients: a critical review

The incidence of arterial ischemic stroke (AIS) in childhood (about 2-13 per 100,000 children a year) is much lower than the incidence in the adult population. Still, adverse outcomes of acute brain ischemia in childhood include death (10% of AIS children), neurological sequel, epileptic seizures (over 50%) and recurrence (over 20%). The knowledge of childhood stroke etiopathogenesis is still insufficient and the diagnostic and therapeutic procedures--controversial. Risk factors for childhood stroke differ from those observed in adults due to differing exposure to external risk factors. The most frequently reported risk factors for pediatric ischemic stroke are cerebral arteriopathies and vascular malformations, cardiac diseases, infections, traumas and metabolic diseases. Because of its multifactorial etiology pediatric AIS probably has a multigenic inheritance pattern. The genetic susceptibility to AIS may be determined by specific polymorphic variants encoding markers of hemostasis regulation and they are some of the most important targets in searching for genetic determinants in pediatric AIS. The authors have reviewed the recent literature on risk factors of childhood ischemic stroke with the focus on genetic factors like polymorphisms of genes encoding coagulation factors II, V, VII and XIII, MTHFR, fibrinogen beta, and compared them with the results performed in adult patients.

Detailed analysis of gene polymorphisms associated with ischemic stroke in South Asians

The burden of stroke is disproportionately high in the South Asian subcontinent with South Asian ethnicity conferring a greater risk of ischemic stroke than European ancestry regardless of country inhabited. While genes associated with stroke in European populations have been investigated, they remain largely unknown in South Asians. We conducted a comprehensive meta-analysis of known genetic polymorphisms associated with South Asian ischemic stroke, and compared effect size of the MTHFR C677T-stroke association with effect sizes predicted from homocysteine-stroke association. Electronic databases were searched up to August 2012 for published case control studies investigating genetic polymorphisms associated with ischemic stroke in South Asians. Pooled odds ratios (OR) for each gene-disease association were calculated using a random-effects model. We identified 26 studies (approximately 2529 stroke cases and 2881 controls) interrogating 33 independent genetic polymorphisms in 22 genes. Ten studies described MTHFR C677T (108 with TT genotype and 2018 with CC genotype) -homocysteine relationship and six studies (735 stroke cases and 713 controls) described homocysteine-ischemic stroke relationship. Risk association ORs were calculated for ACE I/D (OR 5.00; 95% CI, 1.17–21.37; p = 0.03), PDE4D SNP 83 (OR 2.20; 95% CI 1.21–3.99; p = 0.01), PDE4D SNP 32 (OR 1.57; 95% CI 1.01–2.45, p = 0.045) and IL10 G1082A (OR 1.44; 95% CI, 1.09–1.91, p = 0.01). Significant association was observed between elevated plasma homocysteine levels and MTHFR/677 TT genotypes in healthy South Asians (Mean difference (ΔX) 5.18 µmol/L; 95% CI 2.03–8.34: p = 0.001). Our results demonstrate that the genetic etiology of ischemic stroke in South Asians is broadly similar to the risk conferred in Europeans, although the dataset is considerably smaller and warrants the same clinical considerations for risk profiling.

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 TT genotype of methylenetetrahydrofolate reductase 677C>T polymorphism increases the susceptibility to pediatric ischemic stroke: meta-analysis of the 822 cases and 1,552 controls

The 677C>T polymorphism within methylenetetrahydrofolate reductase (MTHFR) gene is related to an elevated level of homocysteine. Thus it may be considered as a genetic risk factor in ischemic stroke. Apparently studies of this type of polymorphism in childhood stroke have shown conflicting results. We performed meta-analysis of all the data that are available in relation with MTHFR polymorphism and the risk of ischemic stroke in children. We searched PubMed (last search dated December 2010) using "MTHFR polymorphism", "ischemic stroke" "child", "children", "pediatric stroke" as keywords and reference lists of studies and reviews on the topic. Finally, 15 case-control studies corresponded to the inclusion criteria for meta-analysis. These studies involved the total number of 822 children and adolescents after ischemic stroke and 1,552 control subjects. Fixed or random effects models were used depending on the heterogeneity between the studies. The association between ischemic stroke and 677C>T polymorphism within MTHFR gene was observed in three of the studies. The pooled analysis showed that TT genotype of MTHFR gene is more common in stroke patients than in controls (p = 0.0402, odds ratio = 1.57, 95 % confidence interval 1.02-2.41). The Egger's test did not reveal presence of a publication bias. The results based on a sizeable group of cases and controls have proved that the 677C>T polymorphism in MTHFR gene is associated with the development of ischemic stroke in children.

Where will the next generation of stroke treatments come from?

Remarkable progress has occurred over the last two decades in stroke interventions. Many have been developed on the basis of their efficacy in other disorders. This "inheritance" approach should continue, but two areas where completely novel therapeutic targets might emerge are the stimulation of neuroplasticity and unraveling the genetic code of stroke heterogeneity (Table 2). For the former, the next steps are to identify small-molecule, nontoxic compounds that most effectively enhance plasticity in animal models, and then subject them to clinical trial in humans. For the latter, more and larger-scale cooperative GWASs in carefully phenotyped stroke populations are required to better understand the polygenic nature of cerebrovascular disease. Then, the physiological relevance of genetic abnormalities can be determined in in vitro and in vivo systems before candidate compounds are developed.