Is there a genetic basis for pediatric stroke?

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.

Genetic mapping and exome sequencing identify 2 mutations associated with stroke protection in pediatric patients with sickle cell anemia

Stroke is a devastating complication of sickle cell anemia (SCA), occurring in 11% of patients before age 20 years. Previous studies of sibling pairs have demonstrated a genetic component to the development of cerebrovascular disease in SCA, but few candidate genetic modifiers have been validated as having a substantial effect on stroke risk. We performed an unbiased whole-genome search for genetic modifiers of stroke risk in SCA. Genome-wide association studies were performed using genotype data from single-nucleotide polymorphism arrays, whereas a pooled DNA approach was used to perform whole-exome sequencing. In combination, 22 nonsynonymous variants were identified and represent key candidates for further in-depth study. To validate the association of these mutations with the risk for stroke, the 22 candidate variants were genotyped in an independent cohort of control patients (n = 231) and patients with stroke (n = 57) with SCA. One mutation in GOLGB1 (Y1212C) and another mutation in ENPP1 (K173Q) were confirmed as having significant associations with a decreased risk for stroke. These mutations were discovered and validated by an unbiased whole-genome approach, and future studies will focus on how these functional mutations may lead to protection from stroke in the context of SCA.

Pediatric stroke: a review

Stroke is relatively rare in children, but can lead to significant morbidity and mortality. Understanding that children with strokes present differently than adults and often present with unique risk factors will optimize outcomes in children. Despite an increased incidence of pediatric stroke, there is often a delay in diagnosis, and cases may still remain under- or misdiagnosed. Clinical presentation will vary based on the child's age, and children will have risk factors for stroke that are less common than in adults. Management strategies in children are extrapolated primarily from adult studies, but with different considerations regarding short-term anticoagulation and guarded recommendations regarding thrombolytics. Although most recommendations for management are extrapolated from adult populations, they still remain useful, in conjunction with pediatric-specific considerations.

Ischemic stroke in infants and children: practical management in emergency

Stroke is a rare disease in children, with an estimated incidence 13/100000 and a significant impact on morbidity and mortality. Clinical presentation and risk factors, present in almost half of pediatric patients, are not the same as in adults. The diagnosis of stroke in children is often delayed because signs and symptoms can be subtle and nonspecific. History and clinical examination should exclude underlying diseases or predisposing factors. Neuroimaging is crucial in defining diagnosis. Other tests might be necessary, according to the clinical picture. We present here the most recent practical directions on how to diagnose and manage arterial stroke in children, according to different international guidelines on the subject.

Treatment challenges in pediatric stroke patients

Aim. In this study we presented our experience of 18 years on the etiology, risk factors, prophylactic and acute treatment, the effect of treatment to recurrence rate of patients with stroke. Methods. The population included 108 patients who had been treated for stroke at Pediatric Neurology Department of Ankara University with the diagnosis of arterial ischemic stroke and sinovenous thrombosis between January 1992 and August 2010. Forty-one girls (38%) and 67 boys (62%) with mean symptom age 3.1 ± 4.04 years, (0–18 years old) were followed up with a mean period of 4.9 ± 3.78 years (0–17 years). Results. 30 patients had no risk factors, 34 patients had only one risk factor and 44 patients had multiple risk factors. Recurrence was seen in three patients. There was no any statistical correlation between the recurrence of stroke and the existence of risk factors (P = .961). Seventeen patients received prophylactic treatment; 2 of them without any risk factors, 3 had one risk factor, 12 patients, who constituted the majority of our patients, had multiple risk factors (P = .024). Conclusion. With this study we showed that the right prophylaxis for right patients reduces the rate of recurrence.

Diagnosis and management of pediatric arterial ischemic stroke

Pediatric stroke is among the top 10 causes of death in children and an important cause of chronic morbidity, with an incidence of 3.3/100,000 children/year. Risk factors associated with stroke in children include cardiac diseases, hematologic and vascular disorders, and infection. Clinical presentation varies depending on age, underlying cause, and stroke location. Antithrombotics and anticoagulants are used in the treatment of pediatric stroke; however, there are no established guidelines for the use of these agents in children. In this article we review the cause, pathophysiology, clinical presentation, diagnosis, acute management, secondary prevention, and outcome of children with stroke. The approach to patients with sickle cell disease and Moyamoya disease is also discussed. Up to date studies to determine the optimal acute treatment of childhood stroke and secondary prevention and risk factor modification are critically needed.

Inherited prothrombotic risk factors in children with stroke, transient ischemic attack, or migraine

OBJECTIVE

The aim of this study was to investigate the prevalence and possible association of inherited prothrombotic risk factors in children with stroke, transient ischemic attack, or migraine.

METHODS

We performed genotypic analysis for factor V G1691A, factor II G20210A, methylenetetrahydrofolate reductase C677T, and 4 common platelet glycoprotein polymorphisms (human platelet alloantigen-1, -2, -3, and -5) in 150 children <18 years of age with established diagnoses of stroke, transient ischemic attack, or migraine. Children were classified into 5 groups, namely, childhood arterial ischemic stroke (N = 33), perinatal arterial ischemic stroke (N = 26), hemorrhagic stroke (N = 20), transient ischemic attack (N = 36), and migraine (N = 35). The control group consisted of 112 children < or =18 years of age from the same geographical region who had no history of neurologic or thromboembolic diseases.

RESULTS

Heterozygosity for factor V G1691A was associated with approximately sevenfold increased risk for arterial ischemic stroke, perinatal arterial ischemic stroke, and transient ischemic attack. Increased risk for transient ischemic attack was found in carriers of the human platelet alloantigen-2b allele, human platelet alloantigen-5a/b genotype, and combined human platelet alloantigen-2b and human platelet alloantigen-5b genotype. The presence of the human platelet alloantigen-2b allele was associated with a 2.23-fold increased risk for migraine, whereas carriers of the human platelet alloantigen-3b allele had a lower risk for arterial ischemic stroke than did carriers of the human platelet alloantigen-3a allele.

CONCLUSIONS

Factor V G1691A has an important role in susceptibility to arterial ischemic stroke, both in the perinatal/neonatal period and in childhood, as well as transient ischemic attacks. A minor impact of human platelet alloantigen polymorphisms suggests that platelet glycoprotein polymorphisms may increase the risk of transient ischemic attacks and migraine, but this should be confirmed in larger studies.

Therapy Insight: stroke risk and its management in patients with sickle cell disease

Children with sickle cell disease, a chronic hemolytic anemia, present with a wide variety of neurological syndromes, including ischemic and hemorrhagic stroke, transient ischemic attacks, 'soft neurological signs', seizures, headache, coma, visual loss, altered mental status, cognitive difficulties, and covert or 'silent' infarction. Those with ischemic stroke usually have stenosis or occlusion of the distal internal carotid and proximal middle cerebral arteries. Indefinite transfusion prevents recurrence in most patients who have had a stroke, and can prevent first stroke in those with high transcranial Doppler velocities. High white cell count, low hemoglobin and oxyhemoglobin desaturation predict neurological complications. Other risk factors for overt ischemic stroke include hypertension, previous transient ischemic attack, covert infarction and chest crisis. For hemorrhagic stroke, aneurysms are common in adults but not children, who often present with hypertension after transfusion or corticosteroids. Seizures are particularly common in patients with cerebrovascular disease and covert infarction; the latter is also associated with hyposplenism and infrequent pain. Factors associated with cognitive difficulties include thrombocytosis, infarction, large-vessel disease, and perfusion abnormality on neuroimaging. As well as investigating the role of genes and the possibility that hydroxyurea or blood pressure control reduce neurological complications, we should explore the modifiable effects of poor nutrition, chronic infection, hemolysis and oxyhemoglobin desaturation on stroke risk.

Mutations and Polymorphisms in Genes Affecting Haemostasis Components in Children with Thromboembolic Events

The distribution of mutations/polymorphisms in genes affecting haemostasis [factor V Leiden (FVL), FV H1298R (FVR(2)), FII 20210A, b-Fib 455G-->A, FXIII V34L, PAI-1 4G, HPA-1b] among 141 children with thrombosis at various sites and 103 controls was compared. Additionally, the carriage of these mutations/polymorphisms was associated with the levels of their corresponding proteins in thrombosed children. Thrombosis was more frequent in boys (p = 0.021). No studied mutation/polymorphism was found to be a risk factor for thrombosis, except for FVL (odds ratio 3.8, 95% CI 1.4-10.6). The risk of thrombosis for FVL carriers was twice as high in children with an idiopathic thrombosis (odds ratio 5.4) than in thrombosed children with an underlying disease or a triggering event (odds ratio 2.7). FVL carriers had an odds ratio of 5.9 (95% CI 1.8-19.6) when FVR(2) was absent. In thrombosed children, the activated protein C resistance ratio was significantly lower in the presence of FVL (p < 0.001). Prothrombin and fibrinogen levels, although higher in FII 20210A and b-Fib 455G-->A carriers, did not reach statistical significance.

Moyamoya syndrome in a child with trisomy 12p syndrome

A female, 2 years and 7 months of age, was admitted to the hospital with stupor and nystagmus following projectile vomiting. She had been prenatally diagnosed with trisomy 12p with a familial pericentric inversion of chromosome 12 originating from her mother. She manifested developmental delay and some dysmorphic features of the face and limbs compatible with the clinical features of trisomy 12p. Four-vessel cerebral angiography revealed severe stenosis and occlusion of the supraclinoid portion of the right and left internal carotid arteries with numerous collateral vessels in the vicinity of the occlusion. These features are consistent with moyamoya syndrome. This report presents the first case of moyamoya syndrome with trisomy 12p with a familial pericentric inversion of chromosome 12.

Computed tomography of pediatric stroke

The causes of stroke in the children are varied. Magnetic resonance imaging (MRI) is generally accepted as the study of choice for definitive diagnosis of ischemic injury. However, often times MRI is not immediately available in the acute setting. This review highlights some of the major causes of stroke in children and the current role of computed tomography (CT), and more specifically, CT angiography in the pediatric setting.

Identification of Patients With Childhood Moyamoya Diseases Showing Temporary Hypertension After Anesthesia by Preoperative Multifractal Hurst Analysis of Heart Rate Variability

OBJECTIVE

This study was performed to determine whether the preoperative multifractal Hurst analysis of heart rate variability might identify and characterize childhood patients with moyamoya disease (MMD) who showed temporary postoperative hypertension.

METHODS

We studied 59 childhood patients with MMD. Thirty were classified as hypertensive group when the mean arterial pressure in the postoperative recovery room was 120% or greater than that during the preoperative period and 29 were classified as normotensive group. The 2 groups were compared with respect to preoperative indices of heart rate variability including frequency-domain measures, approximate entropy, and very short-term multifractal Hurst exponents of RR intervals (RRI). Using preoperative indices that showed significant differences, discriminant analysis was performed to identify postoperative hypertensive patients.

RESULTS

Only exponents of the order > or =3 (H3alpha, H4alpha, and H5alpha) were significantly lower in the hypertensive group than in the normotensive group. Frequency-domain measures, approximate entropy, and the exponents of the order < or =2 were not significantly different in the 2 groups. Discriminant analysis using all of the three exponents correctly identified 27/30 (90%) of the postoperative hypertensive patients.

CONCLUSIONS

Preoperative very short-term multifractal Hurst analysis of RRI variability identified 90% of childhood MMD patients who developed postoperative hypertension. The preoperative characteristic of RRI variability was the reduced smoothness at the 8-second-long, local RRI regions within which a very large change of RRI occurs.

Mutations and polymorphisms in genes affecting hemostasis proteins and homocysteine metabolism in children with arterial ischemic stroke

BACKGROUND

The pathogenesis of thrombosis in childhood seems to be multifactorial implicating genetic and environmental factors.

AIM

To compare the distributions of mutations/polymorphisms in genes affecting hemostasis (factor V Leiden - FVL, FV H1298R-FVR2, FII 20210A, b-Fib 455G>A, FXIII V34L, PAI-1 4G, HPA-1b) or homocysteine metabolism (MTHFR C677T, MTHFR A1298C) among 90 children with arterial ischemic stroke (AIS) and 103 controls, and to associate the carriage of these mutations/polymorphisms with their corresponding proteins in children with AIS.

RESULTS

AIS was more frequent in boys (p < 0.01). No studied mutation/polymorphism was found to be a risk factor for AIS, except for FVL [odds ratio 4.2 (95% CI 1.5-12.1)], the presence of which was even higher in 31 children with congenital AIS [odds ratio 6.82 (95% CI 2.0-22.8)]. FVL carriers had an odds ratio of 5.76 (95% CI 1.6-6.4) when FVR2 was absent. In thrombosed children, activated protein C resistance, prothrombin and fibrinogen levels were higher in the presence of FVL, FII20210A or b-Fib 455G-->A, respectively. Double heterozygotes in both MTHFR C677T and A1298T or homozygotes in one had significantly elevated homocysteine levels.

CONCLUSION

Except for FVL, no definite conclusion could be reached regarding the involvement of the studied mutations/polymorphisms in childhood AIS.

Promoting children's health through understanding of genetics and genomics

PURPOSE

To describe the effects of genetics and genomics on children's health care.

ORGANIZING CONSTRUCT

The breakthroughs in the Human Genome Project have great potential for disease prediction, treatment, and prevention in the health care of children with chronic health conditions. Most childhood conditions based on a single gene are influenced by a complex interaction of genetic and environmental factors.

METHODS

A review of the literature was conducted to determine the most common childhood diseases linked to genetic causes.

FINDINGS

Two examples were selected to depict how a health professional would use genetic knowledge to provide holistic health promotion and disease prevention.

CONCLUSIONS

Knowledge of the interaction of the genetic profile coupled with a person's lifestyle, work environment, and family context provide a more holistic picture of a person's health profile. The clinical implications are that this knowledge will provide opportunities for health professionals to advise families on individualized treatment options or to tailor health promotion to future disease states based on genes and their interaction with the environment.

Thrombosis during infancy and childhood: what we know and what we do not know

Despite underlying illnesses, children have a greater chance to survive and are expected to live 6 to 8 decades following an episode of venous or arterial thrombosis. The disproportionate benefits of preventing thrombosis and its sequelae in pediatric patients are evident. Therefore, it is necessary to develop appropriate strategies for diagnosis and management of thromboembolic events in children and to understand their acute and long-term effects. There still are many unanswered questions and clinical trials are being designed to help study these important issues.