Factor V Leiden and genetic defects of thrombophilia in childhood porencephaly

Can Functional Polymorphisms in VEGF and MMP Predict Intraventricular Hemorrhage in Extremely Preterm Newborns?

BACKGROUND

The pathophysiology of intraventricular hemorrhage (IVH) is multifactorial. This study attempts to identify genetic and clinical factors contributing to IVH in newborns with a focus on those born ≤28 weeks of gestation.

METHODS

This was a prospective study of 382 consecutive newborns admitted to the neonatal intensive care unit. DNA purification was conducted using standard methods. TaqMan SNP assays were conducted for functional polymorphisms in VEGF (RS699947, RS2010963, RS3025039, and RS1570360) and MMP2 (RS243685 and RS2285053) genes. An RFLP assay was done for a polymorphism in MMP9 (RS3918242).

RESULTS

The GG genotype in VEGF RS1570360 (p = 0.013) and the CC genotype in VEGF RS699947 (p = 0.036) were associated with a lower incidence of IVH amongst newborns ≤28 weeks of gestation. Chorioamnionitis, Caucasian race, and patent ductus arteriosus were associated with a higher incidence of IVH. A binary logistic regression analysis of clinical and SNP data that was significant from bivariate analysis demonstrated that VEGF RS1570360 was significantly associated with IVH (p = 0.017).

CONCLUSION

This study demonstrated that the GA/AA genotype in VEGF RS1570360 and the AA/AC genotype in VEGF RS699947 were associated with higher incidence rates of IVH in newborns ≤28 weeks of gestation. A future study is warranted to comprehensively examine VEGF polymorphisms in association with IVH.

Evolution of Factor V Leiden

Factor V Leiden is a procoagulant mutation associated with venous and arterial thrombosis and pregnancy complications. Its high prevalence of 5% in Caucasians suggests that there are evolutionary benefits as well. Carriers are indeed reported to have various advantageous phenotypes related to haemostasis, inflammation and fertility: less acute blood loss; less menstrual blood loss; decreased risk of intracranial haemorrhage; milder phenotypes of haemophilia; higher survival in and lower susceptibility to severe sepsis; higher survival in acute respiratory distress syndrome; less severe diabetic nephropathy and higher fecundity in both men and women. Not all these associations come from high quality adequately powered studies and many have not been confirmed by further research. The evolutionary influence of the alleged associations varies and is difficult to establish, partly due to a shift over time in risk factors of the diseases concerned. For most of the phenotypes possible mechanistic explanations can be provided. The procoagulant phenotype and perhaps also certain pregnancy complications follow from activated protein C (APC) resistance. Elevated APC levels possibly mediate anti-inflammatory effects. Higher sperm counts and more successful embryo implantation seem to play a role in the increased fecundity.

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.

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.

Pathogenesis and prevention of intraventricular hemorrhage

Intraventricular hemorrhage (IVH) is a major neurologic complication of prematurity. Pathogenesis of IVH is attributed to intrinsic fragility of germinal matrix vasculature and to the fluctuation in the cerebral blood flow. Germinal matrix exhibits rapid angiogenesis orchestrating formation of immature vessels. Prenatal glucocorticoid exposure remains the most effective means of preventing IVH. Therapies targeted to enhance the stability of the germinal matrix vasculature and minimize fluctuation in the cerebral blood flow might lead to more effective strategies in preventing IVH.

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.

Cerebral palsy in siblings caused by compound heterozygous mutations in the gene encoding protein C

We report two sisters with extensive bilateral periventricular haemorrhagic infarction (PVHI) causing cerebral palsy (CP). The older sister presented at 20 months with cortical visual blindness, spastic diplegia, and purpura fulminans. The younger sister presented aged 3 days old with apnoeas and multifocal seizures. She subsequently had global developmental delay, cortical visual blindness, spastic quadriplegia, epilepsy, and purpura fulminans at age 2 years. Neuroimaging of both siblings showed bilateral PVHI consistent with bilateral cerebral intramedullary venous thrombosis occurring at under 28 weeks' gestation for the older sister and around time of birth for the younger sister. At latest follow-up, the older sister (13y) has spastic diplegia at Gross Motor Function Classification System (GMFCS) level II, and the younger sister (10y) has spastic quadriplegia at GMFCS level IV. Both sisters showed partial quantitative reduction in plasma protein C antigen and severe qualitative reduction in plasma protein C anticoagulant activity. They were heterozygous for two independent mutations in the protein C gene (PROC). There was no other risk factor for CP. To our knowledge, this is the first family reported with compound heterozygous PROC mutations as the likely genetic cause of familial CP. This report adds to the list of known monogenic causes of CP.

Neonatal thrombo-embolism: risk factors, clinical features and outcome

BACKGROUND

There are few data with respect to prothrombotic risk factors in neonates.

AIM

To determine the associated risk factors, clinical features and outcome in newborn infants diagnosed with thrombo-embolism.

METHODS

Case records of 25 infants (17 full-term and eight preterm) diagnosed with thrombo-embolism between January 2005 and April 2008 in a neonatal intensive care unit were reviewed.

RESULTS

Of the 25 infants, 18 cases of venous (72%) and seven of arterial (28%) thrombo-embolism were recorded; in 18 it was associated with central catheterisation. The sites of thrombosis were portal vein (15), right renal vein (one), right femoral vein (one), multiple veins (one), right femoral artery (3), right iliac artery (2), bilateral iliac and renal arteries (one) and left renal artery (one). Hereditary thrombotic mutations were detected in three patients and anticardiolipin antibody was detected in one, none of whom had been catheterised. The remaining three non-catheterised patients had perinatal risk factors. Venous catheter placement was undertaken in 12 patients (48%), eleven of whom had: umbilical venous catheterisation for exchange transfusion (9), partial exchange transfusion (one) and venous access (one), and one had femoral venous catheterisation for an angiographic study. Arterial catheterisation was undertaken in seven patients (28%) (one infant had both umbilical venous and arterial catheters) for angiographic studies (5) and blood sampling (2). Of the 18 catheterised patients (72%), thrombophilic studies were undertaken in 13 and none had abnormal results. Additional perinatal risk factors were present in 18 patients (72%) and included prematurity (8), congenital heart disease (8), septicaemia (5), dehydration (3), respiratory distress syndrome (3), polycythemia (2), meconium aspiration syndrome (one), pneumonia (one), maternal diabetes (one), necrotising enterocolitis (one) and perinatal asphyxia (one). Although most of the patients recovered after anticoagulant or fibrinolytic therapy, the five (20%) deaths were associated mainly with underlying diseases.

CONCLUSION

The most important risk factor for thrombo-embolic events in neonates is placement of central catheters and some perinatal prothrombotic conditions. Nevertheless, hereditary or acquired thrombophilic risk factors may also be a cause of thrombo-embolism.

Prenatal stroke

The main focus of this chapter is the comprehensive description of the neuropathology, the imaging correlates and underlying mechanisms of prenatal stroke. We describe established prenatal stroke in subgroups similar to postnatal stroke: arterial (forebrain or hindbrain) infarction, venous thrombosis, primary lobar haemorrhage. This longitudinal classification should facilitate the study of risk factors and mechanisms. Forebrain lesions of arterial type present as porencephaly, (hemi)hydranencephaly, multicystic encephalopathy or schizencephaly. Venous prenatal forebrain stroke presents as simple porencephaly (in some of genetic nature) and sinus thrombosis. A list of rare porencephaly-like conditions is added for differentiation from arterial and venous porencephaly. Hindbrain infarctions (so far the only reported variants seem to be of arterial nature) present as brainstem disconnection, focal brainstem destruction, uni- or bilateral cerebellar destruction and focal spinal cord ischaemia. Prenatal intracranial haemorrhage and congenital brain infection should be considered in the differential diagnosis of prenatal stroke.

Association of preterm birth with brain malformations

This study investigates the rate of preterm birth in babies with congenital brain defects. Autopsy case reports of congenital brain anomalies were obtained from the literature. The control cases were from a large registry, a published report from the Metropolitan Atlanta Congenital Defects Program. From 428 publications, 1168 cases were abstracted that had autopsy studies of congenital brain defects and information on the gestational age (GA) at birth. The control data from Atlanta included 7738 infants with significant birth defects of any kind and 264,392 infants without birth defects. In the autopsy cases with brain defects, the mean GA was 36.6 wk, whereas the Atlanta data showed a mean GA of 39.3 wk for infants with no defects and a significantly shorter gestation of 38.1 wk (p < 0.0001) for infants with defects. In the Atlanta data, the rate of preterm birth was 9.3% for those with no defects compared with 21.5% (p < 0.0001) for those with defects. In the autopsy cases with brain defects, the rate of preterm birth was even greater (33.1%, p < 0.0001). In conclusion, these data show an association of brain defects with preterm births.

The diagnosis, management, and postnatal prevention of intraventricular hemorrhage in the preterm neonate

Intraventricular hemorrhage (IVH) occurs in 20% to 25% of very low birthweight preterm neonates and may be associated with significant sequelae. Infants who have IVH are at risk for posthemorrhagic hydrocephalus and periventricular leukomalacia; as many as 75% of those who have parenchymal involvement of hemorrhage suffer significant neurodevelopmental disability. Because of the prevalence of IVH and the medical and societal impact of this disease, many postnatal pharmacologic prevention strategies have been explored. Randomized clinical prevention trials should provide long-term neurodevelopmental follow-up to assess the impact of preterm birth, injury, and pharmacologic intervention on the developing brain.

Maternal thrombophilias are associated with specific placental lesions

Maternal floor infarction (MFI), massive perivillous fibrin deposition (MPVFD), and fetal thrombotic vasculopathy (FTV) are specific placental lesions with associations to recurrent adverse fetal outcomes and with maternal thrombophilia. We studied the frequency of a range of acquired and genetic maternal thrombophilias in MFI (40 cases), MPVFD (87 cases), FTV (7 cases), and FTV+MPVFD (4 cases). Thrombophilias were identified in 16 (40%), 20 (23%), 5 (71%), and 2 (50%) of these lesions, respectively. Seventy-seven percent of the identified thrombophilias were genetic, and 23% were acquired. The most common genetic thrombophilia was protein S deficiency, which constituted 14 of the 36 genetic thrombophilias (39%). We advocate full maternal thrombophilia testing when the diagnosis of MFI, MPVFD, and FTV is made by placental pathology examination. Because of the possible contribution of paternal thrombophilic mutations to the fetal genotype, it would be desirable to test the whole family as well.

Diffuse multicystic encephalomalacia in a preterm baby due to homozygous methylenetetrahydrofolate reductase 677 C-->T mutation

Methylenetetrahydrofolate reductase catalyzes the formation of 5-methyltetrahydrofolate from 5,10-methylentetrahydrofolate and produces folate for the methylation of homocysteine to methionine. Due to insufficient conversion of homocysteine to methionine, plasma homocysteine levels increase in methylenetetrahydrofolate reductase deficiency. Homocysteine is an amino acid that contains a neurotoxic sulfur molecule and can induce neuronal apoptosis. Methylenetetrahydrofolate reductase deficiency is 1 of the etiological factors that causes neurological symptoms and signs in the newborn and childhood period. Here, we report a premature baby with prenatal onset diffuse multicystic encephalomalacia and cerebellar atrophy due to homozygous methylenetetrahydrofolate reductase mutation.

Ischemic perinatal stroke: summary of a workshop sponsored by the National Institute of Child Health and Human Development and the National Institute of Neurological Disorders and Stroke

Ischemic perinatal stroke is a disorder associated with significant long-term neurologic morbidity. With an estimated incidence of 1 in 2300 to 5000 births, stroke is more likely to occur in the perinatal period than at any time in childhood. The incidence of ischemic perinatal stroke ranks second only to that of strokes in the elderly population. Although ischemic perinatal stroke is a well-recognized disorder, many aspects remain to be studied. There is no consensus on its terminology, definition, or classification. Several risk factors have been identified, but their precise roles in causing stroke are not well understood. There are no reliable predictors of ischemic perinatal stroke on which to base prevention or treatment strategies. To review these important issues and propose a research agenda, the National Institute of Child Health and Human Development and the National Institute of Neurological Disorders and Stroke convened a workshop in August 2006. This article provides a summary of the workshop.

Two cousins with neonatal stroke, PAI-1 4G variant and MTHFR A1298C mutation

The authors describe 2 female cousins with neonatal stroke. One was heterozygous for the plasminogen activator inhibitor-1 4G variant and compound heterozygous for the A1298C and C677T methylenetetrahydrofolate reductase mutations. Her cousin was homozygous for the plasminogen activator inhibitor-1 4G variant and heterozygous for the methylenetetrahydrofolate reductase A1298C and factor V Leiden mutations.

Placental histopathologic features in patients with thrombophilic mutations

The purpose of this article is to review the histopathologic findings in the placenta of women with a known thrombophilic mutation. The findings range from normal to severe pathologic features including decidual vasculopathy, placental infarctions, syncytial knotting, maternal floor infarction, fetal thrombotic vasculopathy, vasculitis, and chronic villitis. They are, however, not pathognomonic of thrombophilic states, nor are necessarily markers of perinatal damage. The prospective evaluation of cases with known thrombophilic mutations and the application of tissue microarray examination of the placenta may allow identification of major histopathologic features and molecular parameters associated with maternal and/or fetal thrombophilic states. This may assist clinicians in their consultation with patients and optimize management in future pregnancies.

Different additional risk factors for cerebral infarctions associated with the factor V Leiden mutation in a family

Several cases with cerebral infarctions associated with the factor V Leiden mutation have been reported. However, bearing in mind the large number of asymptomatic individuals with the factor V Leiden mutation, additional risk factors for cerebral infarctions should be considered. In this report, two siblings with cerebral infarctions associated with a combination of heterozygous factor V Leiden mutation and different additional exogenous and endogenous thrombogenic risk factors are described. Respiratory problems in the perinatal period and increased lipoprotein (a) concentrations in the first patient and an episode of gastroenteritis from Shigella infection and persistent high titers of serum anticardiolipin and beta(2)-glycoprotein I antibodies in the second patient were recorded as additional thrombogenic risk factors. Furthermore, both patients were found to be heterozygous for the methylenetetrahydrofolate reductase gene C677T mutation. These findings suggest that even in the same family, different additional thrombogenic risk factors can be present in infants with cerebral infarctions associated with the factor V Leiden mutation. An extensive search of additional circumstantial and genetic thrombogenic risk factors should be useful for prophylaxis and prognosis of these infants with cerebral infarctions associated with the factor V Leiden mutation and of their related family members. To our knowledge, the second patient in this study is the first patient reported to have cerebral infarctions associated with the combination of the factor V Leiden mutation and persistent high titers of serum beta(2)-glycoprotein I antibodies.

Neonatal porencephaly and adult stroke related to mutations in collagen IV A1

OBJECTIVE

The objective of this study was to describe leukoencephalopathy, lacunar infarcts, microbleeds and macrobleeds in the context of a collagen IV A1 mutation.

METHODS

We examined a family with autosomal dominant porencephaly, in whom a defect in collagen IV A1 was detected recently. The patients underwent neurological, ophthalmological, and cardiological examinations and magnetic resonance imaging of the brain. Electron microscopy of a skin biopsy was performed. Extensive laboratory screening was performed for thrombophilia and increased bleeding tendency.

RESULTS

The porencephaly was symptomatic in the infantile period in two patients, whereas it led to only minor neurological dysfunction in their affected mother. However, she experienced development of recurrent strokes in her 40s. In addition to the porencephaly, all patients had a leukoencephalopathy, which was most severe in the mother. Her magnetic resonance imaging results also showed lacunar infarcts, macrobleeds and a multitude of microbleeds. No other risk factors for recurrent stroke were found. Electron microscopy showed interruptions of the basement membrane of skin capillaries and inhomogeneous thickening of the basement membrane with pools of basement membrane fragments.

INTERPRETATION

Leukoencephalopathy, ischemic infarcts, microbleeds, and macrobleeds are indicative of an underlying microangiopathy, of which the best-known causes are hypertension, cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy, and cerebral amyloid angiopathy. Mutations in collagen IV A1, a major component of the vascular basement membrane, appear to be another risk factor.

Schizencephaly: heterogeneous etiologies in a population of 4 million California births

Schizencephaly is a rare congenital brain defect characterized by gray matter lined clefts of the cerebral mantle, frequently accompanied by other defects of the CNS such as absence of the corpus callosum. This study in a California population of >4 million births from 1985-2001 found a population prevalence of 1.54/100,000. Among 63 cases, there was an association with young parental age in isolated schizencephaly (RR 3.9 mothers; 5.8 fathers), which was also seen in mothers but not fathers of non-isolated cases (RR 3.2). Monozygotic twins may also be at increased risk for schizencephaly (RR 2.1). One third of cases had a non-CNS abnormality, over half of which could be classified as secondary to vascular disruption, including gastroschisis, bowel atresias, and amniotic band disruption sequence. Other apparent rare causes included chromosomal aneuploidy, non-random associations, and unusual syndromes. Our observations suggest that schizencephaly has heterogeneous etiologies many of which are vascular disruptive in origin.

Novel mutations in three families confirm a major role of COL4A1 in hereditary porencephaly

BACKGROUND

Porencephaly (cystic cavities of the brain) is caused by perinatal vascular accidents from various causes. Several familial cases have been described and autosomal dominant inheritance linked to chromosome 13q has been suggested. COL4A1 is an essential component in basal membrane stability. Mouse mutants bearing an in-frame deletion of exon 40 of Col4a1 either die from haemorrhage in the perinatal period or have porencephaly in survivors. A report of inherited mutations in COL4A1 in two families has shown that familial porencephaly may have the same cause in humans.

OBJECTIVE

To describe three novel COL4A1 mutations.

RESULTS

The three mutations occurred in three unrelated Dutch families. There were two missense mutations of glycine residues predicted to result in abnormal collagen IV assembly, and one mutation predicted to abolish the traditional COL4A1 start codon. The last mutation was also present in an asymptomatic obligate carrier with white matter abnormalities on brain magnetic resonance imaging.

CONCLUSIONS

This observation confirms COL4A1 as a major locus for genetic predisposition to perinatal cerebral haemorrhage and porencephaly and suggests variable expression of COL4A1 mutations.

Genetic risk factors associated with thrombosis in children with congenital neurologic disorders

Thromboembolic events during the perinatal period are responsible for irreversible brain damage owing to cerebral hypoxia and neuronal necrosis. We investigated the presence of thrombophilia risk factors in children with congenital neurologic disorders. Nineteen children (9 males and 10 females), aged 1 to 14 years (median 4.5 years), who had presented with symptoms and signs of congenital neurologic disorders were studied. Thirty-five age-matched healthy children recruited from the same geographic area served as controls. Three patients of 19 (15.8%) were carrying the factor V Leiden mutation compared with 2 children among the controls (5.7%). One patient was heterozygous for the prothrombin G20210A variant (5.2%) compared with one child who was heterozygous among the controls. Three patients were homozygous (15.8%) and 11 were heterozygous (57.9%) for the C677T 5,10-methylenetetrahydrofolate reductase gene mutation compared with 4 (11.5%) and 18 (51.4%), respectively, among the controls. Three patients of 19 (15.8%) were carrying more than one mutation. We found 18 mutations in 79% (15/19) of the patients and 25 mutations in 69% (24/35) of the healthy children. Among the individuals carrying the homozygous 677TT 5,10-methylenetetrahydrofolate reductase genotype, we found 7 mutations in 32% (6/19) of the patients and 7 mutations in 20% (7/35) of the healthy children (P > .05). In one patient, lupus anticoagulant and antiphospholipid antibodies of IgG isotype were detected. Reduced activities of protein C, protein S, or antithrombin III were not observed in either the patient or the control group. Although, among our cases, we found some well-known risk factors associated with thrombosis in adults, the pathogenesis of these clinical entities remains obscure.

Thromboembolic Diseases in Neonates and Children

Acquired and inherited prothrombotic risk factors increase the risk of thrombosis in neonates, infants and children. After suffering thrombosis white paediatric patients should be screened for common gene mutations, i.e. the factor V G1691A, factor II G20210A and MTHFR C677T genotypes, rare inherited prothromboticrisk factors, i.e. deficiencies of protein C,protein S, and antithrombin, plasminogen, probably inherited risk factors, i.e. fibrinogen, factor VIIIC, factor XII, new candidates, i.e. elevation of lipoprotein (a),and fasting homocysteine concentrations (3-6 months after thrombotic onset). Data interpretation is based on age-dependent reference ranges or the identification of causative gene mutations/polymorphisms with respect to individual ethnic backgrounds.

Antithrombotic Therapy in Children*

This article about antithrombotic therapy in children is part of the 7th American College of Chest Physicians Conference on Antithrombotic and Thrombolytic Therapy: Evidence-Based Guidelines. Grade 1 recommendations are strong and indicate that the benefits do, or do not, outweigh the risks, burden, and costs. Grade 2 suggests that individual patients' values may lead to different choices (for a full understanding of the grading see Guyatt et al, CHEST 2004; 126:179S-187S). Among the key recommendations in this article are the following. In neonates with venous thromboembolism (VTE), we suggest treatment with either unfractionated heparin or low-molecular-weight heparin (LMWH), or radiographic monitoring and anticoagulation therapy if extension occurs (Grade 2C). We suggest that clinicians not use thrombolytic therapy for treating VTE in neonates, unless there is major vessel occlusion that is causing the critical compromise of organs or limbs (Grade 2C). For children (ie, > 2 months of age) with an initial VTE, we recommend treatment with i.v. heparin or LMWH (Grade 1C+). We suggest continuing anticoagulant therapy for idiopathic thromboembolic events (TEs) for at least 6 months using vitamin K antagonists (target international normalized ratio [INR], 2.5; INR range, 2.0 to 3.0) or alternatively LMWH (Grade 2C). We suggest that clinicians not use thrombolytic therapy routinely for VTE in children (Grade 2C). For neonates and children requiring cardiac catheterization (CC) via an artery, we recommend i.v. heparin prophylaxis (Grade 1A). We suggest the use of heparin doses of 100 to 150 U/kg as a bolus and that further doses may be required in prolonged procedures (both Grade 2 B). For prophylaxis for CC, we recommend against aspirin therapy (Grade 1B). For neonates and children with peripheral arterial catheters in situ, we recommend the administration of low-dose heparin through a catheter, preferably by continuous infusion to prolong the catheter patency (Grade 1A). For children with a peripheral arterial catheter-related TE, we suggest the immediate removal of the catheter (Grade 2C). For prevention of aortic thrombosis secondary to the use of umbilical artery catheters in neonates, we suggest low-dose heparin infusion (1 to 5 U/h) (Grade 2A). In children with Kawasaki disease, we recommend therapy with aspirin in high doses initially (80 to 100 mg/kg/d during the acute phase, for up to 14 days) and then in lower doses (3 to 5 mg/kg/d for > or = 7 weeks) [Grade 1C+], as well as therapy with i.v. gammaglobulin within 10 days of the onset of symptoms (Grade 1A).

The factor V G1691A mutation is a risk for porencephaly: A case-control study

This study was initiated to investigate prothrombotic risk factors in children with porencephaly. 76 porencephalic and 76 healthy infants were investigated for factor V (FV) G1691A mutation, factor II G20210A variant, methylenetetrahydrofolate reductase (MTHFR) C677T genotype, lipoprotein (a), protein C, protein S, and antithrombin. Only the FV mutation (p = 0.005) and combinations of two or three different risk factors (p = 0.003) were significantly associated with porencephaly. These data give evidence that the FV G1691A mutation and a combination of prothromboic factors play a major role in the development of childhood porencephaly.

Stroke in newborn infants

The few days before and after birth are a time of special risk for stroke in both mother and infant, probably related to activation of coagulation mechanisms in this critical period. Arterial ischaemic stroke around the time of birth is recognised in about one in 4000 full-term infants, and may present with neurological and systemic signs in the newborn. Neonatal seizures are most commonly the clinical finding that triggers assessment. In other children, perinatal stroke is recognised only retrospectively, with emerging hemiparesis or seizures after the early months of life. Risk factors for perinatal stroke include hereditary or acquired thrombophilias and environmental factors. Perinatal stroke underlies an important share of congenital hemiplegic cerebral palsy, and probably some spastic quadriplegic cerebral palsy and seizure disorders. There is much to be learned about the natural history of perinatal stroke, and there are as yet no evidence-based strategies for prevention or treatment.

Hereditary porencephaly: clinical and MRI findings in two Dutch families

Familial porencephaly is a rare disorder causing motor impairment, hemiplegia, mental retardation and epilepsy in variable degrees. Two families with porencephaly and apparently dominant inheritance are reported. Brain MRI findings are reviewed and described in seven affected individuals. Most patients also show white matter abnormalities in the cerebral hemisphere, also contralateral to the cystic lesion. In the first family an obligate carrier was identified who did not have a cystic lesion but clear abnormalities of the white matter. Although a predisposition for thrombophilia has previously been reported, we did not observe any genetic, environmental or epigenetic predisposition for the porencephaly. The lesions are most compatible with a deep venous thrombosis/ischemic event occurring in a late stage of pregnancy, not necessarily aggravated by perinatal asphyxia.

Challenge of conducting trials of neuroprotection in the asphyxiated term infant

There has been much progress in understanding the pathogenesis of hypoxic-ischemic brain injury in the near-term and term infant. Although gaps in our knowledge base persist, advances over the past two decades have led to the development of specific brain oriented therapies directed at critical events contributing to tissue damage. The primary goal of these interventions is to prevent or attenuate neurologic and developmental sequelae of brain injury. Examples of current potential treatments include modest reductions in brain temperature, receptor antagonists of excitatory neurotransmitters, reductions in O2 free radicals, blockade of inflammatory mediators, and inhibition of apoptotic pathways. At present, some of these treatments have sufficient animal data that demonstrate benefit, to justify moving experiments from the laboratory to the clinical arena. Modest hypothermia represents the neuroprotective intervention that has been investigated in the most complete fashion for the newborn, and there are multiple ongoing clinical trials testing its efficacy. This review will address specific challenges that are pertinent to the evaluation of any neuroprotective therapy implemented shortly after birth. Specific issues to be covered include the therapeutic window, establishing a diagnosis of hypoxic-ischemic encephalopathy, patient selection, characteristics of an effective therapy, safety considerations, appropriate outcome variables, and sample size considerations. Since clinical trials of brain hypothermia are in progress, many of these issues will be addressed from the perspective of this specific intervention.

Maternal thrombophilia and neonatal thrombosis

In neonates and infants, numerous clinical and environmental conditions lead to elevated thrombin generation and subsequent thrombus formation. Genetic prothrombotic defects (protein C, protein S and antithrombin deficiency, mutations of coagulation factor V and factor II, elevated lipoprotein (a)) have been established as risk factors of thromboembolic events in neonates and infants. The interpretation of the laboratory evaluation relies on age-dependent normal reference values. Because appropriate clinical trials are missing in these age groups, treatment recommendations are adapted from small-scale studies in neonates and infants and from guidelines relating to adult patient protocols. Secondary long-term anticoagulation should be administered on an individual basis.

Prothrombotic factors in neonates with cerebral thrombosis and intraventricular hemorrhage

AIM

To investigate whether the factor V Leiden mutation (FVL), the prothrombin gene G20210A variant or the methylenetetrahydrofolate reductase (MTHFR) C677T genotype are risk factors for central nervous system (CNS) thrombosis or intraventricular hemorrhage (IVH) in neonates.

METHODS

Thirteen full-term infants with cerebral infarct documented with magnetic resonance imaging were assessed with the whole spectrum of assays for thrombophilia including the three DNA-based prothrombotic factors. The frequency of congenital defects was compared with that observed in 38 healthy full-term infants. The genetic defects were also assessed in 55 premature neonates, gestational age <32 wk, 17 of whom developed IVH, grade II-IV. The remaining 38 premature neonates without IVH were used as controls.

RESULTS

In the CNS thrombosis group: a prothrombotic factor was detected in 53% of patients and an underlying disease or a triggering event in 61.5%. The frequency of FVL in thrombosed neonates was higher (23%) than in the group of healthy full-term infants (10.5%), although it did not reach statistical significance. IVH developed in 30.9% of premature neonates. Apart from several maternal or neonatal risk factors for IVH, FII G20210A was found in a considerably higher prevalence in the cohort of neonates with IVH (12%) than in those without (2%), although the difference was not statistically significant.

CONCLUSION

The pathogenesis of cerebral thrombosis or IVH in neonates is multifactorial. Along with underlying diseases or triggering events, congenital prothrombotic factors (FVL or FII G20210A) showed a trend towards a higher frequency in full-term infants with CNS thrombosis or premature neonates with IVH than in controls. However, their contribution to neonatal cerebral thrombosis or IVH remains to be determined.

Neuroimaging fails to identify asymptomatic carriers of familial porencephaly

Familial porencephaly is a rare condition usually transmitted as an autosomal dominant trait with incomplete penetrance. We describe a new family in which six members across four generations had congenital hemiplegia. Cerebral imaging was performed in three patients and showed porencephaly in all cases. In order to provide effective genetic counseling, three asymptomatic carriers were investigated by cerebral computerized tomography (three patients) and cerebral magnetic resonance imaging (one patient). These investigations failed to show any congenital abnormalities. We conclude that cerebral imaging is unreliable to detect obligate carriers of familial porencephaly.

Pediatric thrombosis

Although thrombosis is less frequent in children than in adults, it represents a significant source of morbidity and mortality. Multiple factors. both genetic and acquired. contribute to the development of thrombosis in chiidren. Thrombosis in a child warrants investigation of potential underlying prothrombotic conditions. The risk of thrombosis in children with heterozygous deficiencies is not clearly defined, but it appears that children who are heterozygous for more than one risk factor or who have a combination of inherited and acquired defects are at higher risk for thrombosis. Treatment of thrombosis primarily involves a rapidly acting anticoaguiant such as heparin or LMWH to prevent extension, and long-term anticoagulation with warfarin may be instituted to prevent recurrence. Thrombolytic therapy with recombinant tissue plasminogen activator also appears to be safe and effective in children. Prospective and multicenter studies are still needed to clarify the contribution of specific prothrombotic disorders to childhood TE so that evidence-based treatment recommendations can be made.

Diagnostic studies for thrombophilia in women on hormonal therapy and during pregnancy, and in children

OBJECTIVE

To review the role of acquired and inherited prothrombotic risk factors that increase the risk of thrombosis in oral contraceptive users, during pregnancy, and in neonates, infants, and children; and to determine by the consensus opinion of recognized experts in the field which risk factors should be determined in which individuals at which time.

DATA SOURCES

Review of the medical literature and current clinical practice by a panel of experts in the field of thrombophilia.

DATA EXTRACTION AND SYNTHESIS

The experts made an extensive review of the published literature and prepared a draft manuscript, which included preliminary recommendations. The draft manuscript was circulated to participants in the College of American Pathologists Conference XXXVI: Diagnostic Issues in Thrombophilia prior to the conference. The manuscript and recommendations were then presented at the conference for discussion. Recommendations were accepted if a consensus of the 26 experts attending the conference was reached. The results of the discussion were used to revise the manuscript into its final form.

CONCLUSIONS

This report reviews the options for testing for thrombophilic states in women using oral contraceptives, during pregnancy, and in neonates and children. General guidelines for testing in these clinical situations are provided, along with citation of the appropriate supporting literature.

Thromboembolic disease and antithrombotic therapy in newborns

This update uses an evidence based approach to analyze and present the epidemiology of neonatal thrombosis, etiologies, currently used techniques for diagnosis with their limitations, and current therapeutic approaches. In addition, the approaches to both prevention and optimal therapies are discussed. In Section I Dr. Paul Monagle addresses the epidemiology of neonatal thrombosis outside of the central nervous system in both arterial and venous locations, and those that occur in utero. The specific contributions of catheters and congenital prothrombotic disorders are delineated. Dr. Monagle also describes currently used techniques for the diagnosis of thrombotic events as well as their limitations and the current therapeutic approaches. In Section II, Dr. Gabrielle deVeber reviews the epidemiology of neonatal thrombosis within the central nervous system, in both arterial and venous locations and those that occur in utero. The neurological presentation, risk factors including congenital prothrombotic disorders, anatomical distribution, diagnostic tests, use of antithrombotic therapy and neurologic outcome of neonates with either sinovenous thrombosis or arterial ischemic stroke are discussed. In Section III, Dr. Anthony Chan reviews the current approaches to the prevention and treatment of neonatal thrombosis. Information on the differences in the response of neonates compared to adults to antithrombotic therapy and new approaches to the prevention and treatment of thrombosis in neonates are emphasized.

Epidemiology of perinatal stroke

Perinatal stroke has become increasingly recognized, but the incidence is probably underestimated because of variation in the presentation, evaluation, and diagnosis. Based on estimates from population-based studies of infants with seizures, perinatal stroke occurs in approximately 1 in 4000 term births. Most perinatal strokes involve the middle cerebral artery and are caused by thromboembolism from an intracranial or extracranial vessel, the heart, or the placenta. Cardiac disorders, coagulation abnormalities, and infection are risk factors for stroke in the perinatal period. This article discusses the epidemiology of ischemic stroke occurring in the perinatal and neonatal period, including cerebrovascular events that are diagnosed during the perinatal period and those diagnosed retrospectively, when evidence of hemiparesis or postneonatal seizures leads to later evaluation and neuroimaging.

Cerebrovascular disorders in children with the factor V Leiden mutation

Since 1995, at least 128 children with a cerebrovascular disorder, cerebral palsy, or both and the factor V Leiden mutation have been reported. The majority of these strokes were in the first year of life, many of them in the perinatal period. Two thirds had an additional exogenous risk factor for thrombosis, and 42% had another recognized endogenous prothrombotic risk factor in combination with the mutation. We review the association of the factor V Leiden mutation and a cerebrovascular disorder in children younger than 16 years of age and describe the clinical features of 8 children with cerebral palsy and the Leiden mutation. This mutation should be considered in the evaluation of children with a stroke or its sequelae, including infants with perinatal stroke.

Prothrombotic disorders and abnormal neurodevelopmental outcome in infants with neonatal cerebral infarction

BACKGROUND AND PURPOSE

The aim of this study was to evaluate the occurrence of prothrombotic disorders in a well-characterized cohort of infants with neonatal stroke and to document any association of prothrombotic disorders with the type of infarct seen on magnetic resonance imaging (MRI) and clinical outcome.

METHODS

Twenty-four infants with perinatal cerebral infarction confirmed by neonatal MRI were enrolled in the study. All the infants and, when possible, both parents were tested to identify inherited and acquired prothrombotic disorders.

RESULTS

None of the infants had a significant bleeding diathesis, but 10 (42%) had at least 1 prothrombotic risk factor. Five children showed heterozygosity for factor V Leiden, and 6 had high factor VIIIc concentrations. There was a striking association between the occurrence of these abnormalities and both the presence of cerebral hemorrhage on MRI and poor neurologic outcome. Eight of the 11 patients (73%) with hemiplegia or global developmental delay had factor V Leiden and/or raised factor VIIIc, whereas only 1 of the 13 patients (8%) with normal outcome had any prothrombotic risk factors. In particular, all 5 infants with factor V Leiden had hemiplegia, compared with only 4 of the 19 infants without factor V Leiden (21%).

CONCLUSIONS

These data suggest that the presence of prothrombotic risk factors and, in particular, of the factor V Leiden mutation, is significantly associated with poor outcome after perinatal cerebral infarction.

Symptomatic ischemic stroke in full-term neonates : role of acquired and genetic prothrombotic risk factors

BACKGROUND AND PURPOSE

The present multicenter case-control study was prospectively designed to assess the extent to which single and combined clotting factor abnormalities influence the onset of symptomatic ischemic stroke in full-term neonates.

METHODS

Lipoprotein (Lp)(a); the factor V (FV) G1691A mutation; the prothrombin (PT) G20210A variant; the methylenetetrahydrofolate reductase (MTHFR) T677T genotype; antithrombin; protein C; protein S; and anticardiolipin antibodies (ACAs) were investigated in 91 consecutively recruited neonatal stroke patients and 182 age- and sex-matched healthy controls.

RESULTS

Sixty-two of 91 stroke patients (68.1%) had at least 1 prothrombotic risk factor compared with 44 control subjects (24.2%) (odds ratio [OR]/95% confidence interval [CI], 6.70/3.84 to 11.67). An increased Lp(a) level (>30 mg/dL) was found in 20 patients and 10 controls (OR/95% CI, 4.84/2. 16 to 10.86); FV G1691A was present in 17 patients and 10 controls (OR/95% CI, 3.95/1.72 to 9.0); the PT G20210A variant was detected in 4 patients and 4 controls (OR/95% CI, 2.04/0.49 to 8.3); the MTHFR TT677 genotype was found in 15 patients and 20 controls (OR/95% CI, 1.59/0.77 to 3.29); and protein C type I deficiency was found in 6 neonates. Neither antithrombin deficiency nor protein S deficiency was found in the neonatal patients studied. Acquired IgG ACAs were found in 3 cases. Additional triggering factors, ie, asphyxia, septicemia, maternal diabetes, and perinatally acquired renal venous thrombosis, were reported in 54.0% of patients.

CONCLUSIONS

Besides acquired triggering factors, the data presented here suggest that genetic prothrombotic risk factors play a role in symptomatic neonatal stroke.

Postoperative stroke in a child with cerebral palsy heterozygous for factor V Leiden

A 5-year-old with spastic quadraparetic cerebral palsy suffered multiple strokes after extensive orthopedic surgery. Coagulation testing was undertaken to determine whether a familial thrombophilia was present. The patient was found to be heterozygous for factor V Leiden. Factor V Leiden may be a risk factor for central nervous system events in special-needs children, particularly when common medical conditions create additional procoagulant risks.

A pilot study of the possible role of familial defects in anticoagulation as a cause for terminal limb reduction malformations

Terminal limb deficiency defects affect between three and eight babies per 10000 births and are an important cause of disability. Established causes for these malformations include single gene disorders, chromosome abnormalities, teratogens, and amniotic bands. However, the etiology remains unknown in a significant proportion of cases. Several authors have hypothesized that vascular accidents, either bleeds or vessel occlusions, may underlie a substantial number of cases; but, for the most part, the origin of such events remains obscure. Over the past several years, an increasing number of genetic thrombophilias have been recognized and have been associated with increased risks of peri- and post-natal occlusive disease, and with higher rates of recurrent pregnancy loss. The hypothesis to be examined in this pilot study was whether the inherited thrombophilias might be associated with a vascular cause of some terminal limb deficiency defects. Towards that end, protein C, protein S, antithrombin III, factor V Leiden mutation, prothrombin (G20210A) variant, methylenetetrahydrofolate reductase variant, plasma homocysteine, anticardiolipin IgM and IgG antibodies, and lipoprotein (a) were measured in 24 mother-child pairs in which the child had a terminal limb defect. The results provided some evidence that there may be an excess of thrombophilias present in such families and that they may play some etiological role in a subset of these types of limb malformations.

Lipoprotein (a) and Genetic Polymorphisms of Clotting Factor V, Prothrombin, and Methylenetetrahydrofolate Reductase Are Risk Factors of Spontaneous Ischemic Stroke in Childhood

Ischemic stroke is a rare event in childhood. In approximately one third of cases no obvious underlying cause or disorder can be detected. We investigated the importance of genetic risk factors of venous thromboembolism in childhood or stroke in adulthood as risk factors for spontaneous ischemic stroke in children. One hundred forty-eight Caucasian infants and children (aged 0.5 to 16 years) with stroke and 296 age-matched controls from the same geographic areas as the patients were analyzed for increased lipoprotein (a) [Lp(a)] levels >30 mg/dL; for the presence of the factor V (FV) G1691A mutation, the prothrombin (PT) G20210A variant, and the TT677 genotype of methylenetetrahydrofolate reductase (MTHFR); and deficiencies of protein C, protein S, and antithrombin. The following frequencies (patients v controls), odds ratios (ORs), and confidence intervals (CIs) of single risk factors were found: Lp(a) >30 mg/dL (26.4% v 4.7%; OR/CI, 7.2/3.8 to 13.8; P < .0001), FV G1691A (20.2% v 4%; OR/CI, 6/2.97 to 12.1; P < .0001), protein C deficiency (6% v 0.67%; OR/CI, 9.5/2 to 44.6; P = .001), PT G20210A (6% v 1.3%; OR/CI, 4.7/1.4 to 15.6; P = .01), and the MTHFR TT677 genotype (23.6% v 10.4%; OR/CI, 2.4/1.53 to 4.5; P < .0001). A combination of the heterozygous FV G1691A mutation with increased Lp(a) (n = 11) or the MTHFR TT677 genotype (n = 5) was found in 10.8% of cases, but only 0.3% of controls (OR/CI, 35.75/4.7 to 272;P < .0001). Increased Lp (a) levels, the FV G1691A mutation, protein C deficiency, the prothrombin G20210A variant, and the MTHFR TT677 are important risk factors for spontaneous ischemic stroke in childhood.

Lipoprotein (a) and Genetic Polymorphisms of Clotting Factor V, Prothrombin, and Methylenetetrahydrofolate Reductase Are Risk Factors of Spontaneous Ischemic Stroke in Childhood

Ischemic stroke is a rare event in childhood. In approximately one third of cases no obvious underlying cause or disorder can be detected. We investigated the importance of genetic risk factors of venous thromboembolism in childhood or stroke in adulthood as risk factors for spontaneous ischemic stroke in children. One hundred forty-eight Caucasian infants and children (aged 0.5 to 16 years) with stroke and 296 age-matched controls from the same geographic areas as the patients were analyzed for increased lipoprotein (a) [Lp(a)] levels &gt;30 mg/dL; for the presence of the factor V (FV) G1691A mutation, the prothrombin (PT) G20210A variant, and the TT677 genotype of methylenetetrahydrofolate reductase (MTHFR); and deficiencies of protein C, protein S, and antithrombin. The following frequencies (patients v controls), odds ratios (ORs), and confidence intervals (CIs) of single risk factors were found: Lp(a) &gt;30 mg/dL (26.4% v 4.7%; OR/CI, 7.2/3.8 to 13.8; P &lt; .0001), FV G1691A (20.2% v 4%; OR/CI, 6/2.97 to 12.1; P &lt; .0001), protein C deficiency (6% v 0.67%; OR/CI, 9.5/2 to 44.6; P = .001), PT G20210A (6% v 1.3%; OR/CI, 4.7/1.4 to 15.6; P = .01), and the MTHFR TT677 genotype (23.6% v 10.4%; OR/CI, 2.4/1.53 to 4.5; P &lt; .0001). A combination of the heterozygous FV G1691A mutation with increased Lp(a) (n = 11) or the MTHFR TT677 genotype (n = 5) was found in 10.8% of cases, but only 0.3% of controls (OR/CI, 35.75/4.7 to 272;P &lt; .0001). Increased Lp (a) levels, the FV G1691A mutation, protein C deficiency, the prothrombin G20210A variant, and the MTHFR TT677 are important risk factors for spontaneous ischemic stroke in childhood.

Causes of cerebral palsy

Risk factors for cerebral palsy in term or near-term children include intrauterine exposure to infection or inflammation and disorders of coagulation. Interruption of the oxygen supply during birth contributes approximately 6% of spastic cerebral palsy. Low Apgar score, need for resuscitation, and seizures are nonspecific indicators of neonatal illness that do not identify cause. Although not entirely consistent, current evidence suggests that in utero infection may predispose very preterm and more mature infants to cerebral palsy and that antenatal exposure to steroids may be somewhat protective. Recognition of a broader set of causal possibilities encourages hope for new strategies for the prevention of cerebral palsy.

The neurologically impaired child and alleged malpractice at birth

Controlled studies, improved epidemiologic and statistical techniques, and an increase in biological information on mechanisms of fetal and neonatal brain injury or maldevelopment have led to a better, although still imperfect, understanding of the cause of developmental disabilities. The role of asphyxia during the birth process is smaller than was once believed. Intrauterine exposure to infection, autoimmune and coagulation disorders, and problems specific to multiple pregnancies are risk factors for cerebral palsy. Electronic fetal monitoring and other observations during birth are unsatisfactory management guides, having enormously high rates of false-positive identification. There is no evidence that caesarean section can prevent cerebral palsy in term infants.