The association of genetic polymorphisms with cerebral palsy: a meta-analysis

Causation in cerebral palsy: Parental beliefs and associated emotions

AIM

To better understand parents' beliefs about causation in cerebral palsy (CP) and the emotions related to those beliefs.

METHOD

We surveyed 226 parents of children with CP aged 1 to 18 years, recruited from the Victorian Cerebral Palsy Register, to evaluate their beliefs about the causes of CP, including genetic causes, causes specific to their own child, and their attitudes and emotions in relation to these.

RESULTS

Although 92% of participants reported that understanding the causes of their child's CP was important, uncertainty about the cause was expressed by 13%. The most frequently endorsed causal factors, in general and in their own child respectively, were intrapartum hypoxia (81%, 36%) or brain damage (69%, 22%), brain damage during pregnancy (73%, 28%), and preterm birth (66%, 28%). Genetic causes were deemed relevant by 13% of participants and hospital or professional error by 16%. Parents shared related feelings of anger (59%), sadness (80%), guilt (61%), and confusion (53%); parental anger was more likely when their child's CP was attributed to intrapartum events.

INTERPRETATION

Substantial parental interest in understanding the causes of CP, together with uncertainty about the causes, parents' causal attributions, and significant emotional sequelae, highlight a strong need for provision of information and support for families of children recently diagnosed with CP.

WHAT THIS PAPER ADDS

Understanding the causes of their child's cerebral palsy (CP) was important to parents. Parents most often endorsed intrapartum factors as a cause of CP. Parents reported experiencing strong emotions about the causes of their child's CP.

Candidate genes related to acute cerebral circulatory disorders in Preeclampsia in the Kazakh Population

BACKGROUND

The purpose of this study is to conduct a comparative analysis of the population frequencies of alleles and genotypes of polymorphic variants of coagulation and fibrinolysis genes SERPINE1 rs1799889, ITGA2 rs1126643, THBD rs1042580, FII rs1799963, FV rs6025, FVII rs6046, angiogenesis and endothelial dysfunction PGF rs12411, FLT1 rs4769612, KDR rs2071559, ACE rs4340, GWAS associated with the development of acute cerebral circulatory disorders in preeclampsia, in an ethnically homogeneous population of Kazakhs with previously studied populations of the world.

METHODS

The genomic database was analysed based on the results of genotyping of 1800 conditionally healthy individuals of Kazakh nationality ∼2.5 million SNPs using OmniChip 2.5 M Illumina chips at the DECODE Iceland Genomic Center as part of the joint implementation of the project "Genetic Studies of Preeclampsia in Populations of Central Asia and Europe" (InterPregGen) within the 7th Framework Programme of the European Commission under Grant Agreement No. 282540.

RESULT

The study discovered a significantly higher population frequency of carrying the unfavorable rs1126643 allele of the ITGA2 gene polymorphism when compared with European populations. The population frequencies of carrying minor alleles of the SERPINE1 (rs179988) and KDR (rs2071559) genes in the Kazakh population were significantly lower when compared with the previously studied populations of Europe and Asia. An intermediate frequency of unfavorable minor alleles between European and Asian populations was found in Kazakhs for gene polymorphisms: FV rs6025, PGF rs12411, and ACE rs4340. The genomic analysis determined the choice of polymorphisms for their further replicative genotyping in patients with ACCD in PE in the Kazakh population.

CONCLUSION

The obtained results will serve as a basis for the development of effective methods of early diagnosis and treatment of PE in pregnant women, carriers of unfavorable genotypes.

Cerebral palsy and related neuromotor disorders: Overview of genetic and genomic studies

Cerebral palsy (CP) is a debilitating condition characterized by abnormal movement or posture, beginning early in development. Early family and twin studies and more recent genomic investigations clearly demonstrate that genetic factors of major effect contribute to the etiology of CP. Most copy number variants and small alterations of nucleotide sequence that cause CP arise as a result of de novo mutations, so studies that estimate heritability on basis of recurrence frequency within families substantially underestimate genetic contributions to the etiology. At least 4% of patients with typical CP have disease-causing CNVs, and at least 14% have disease-causing single nucleotide variants or indels. The rate of pathogenic genomic lesions is probably more than twice as high among patients who have atypical CP, i.e., neuromotor dysfunction with additional neurodevelopmental abnormalities or malformations, or with MRI findings and medical history that are not characteristic of a perinatal insult. Mutations of many different genetic loci can produce a CP-like phenotype. The importance of genetic variants of minor effect and of epigenetic modifications in producing a multifactorial predisposition to CP is less clear. Recognizing the specific cause of CP in an affected individual is essential to providing optimal clinical management. An etiological diagnosis provides families an "enhanced compass" that improves overall well-being, facilitates access to educational and social services, permits accurate genetic counseling, and, for a subset of patients such as those with underlying inherited metabolic disorders, may make precision therapy that targets the pathophysiology available. Trio exome sequencing with assessment of copy number or trio genome sequencing with bioinformatics analysis for single nucleotide variants, indels, and copy number variants is clinically indicated in the initial workup of CP patients, especially those with additional malformations or neurodevelopmental abnormalities.

The NESHIE and CP Genetics Resource (NCGR): A database of genes and variants reported in neonatal encephalopathy with suspected hypoxic ischemic encephalopathy (NESHIE) and consequential cerebral palsy (CP)

Neonatal encephalopathy (NE) with suspected hypoxic ischaemic encephalopathy (HIE) (NESHIE) is a complex syndrome occurring in newborns, characterised by altered neurological function. It has been suggested that genetic variants may influence NESHIE susceptibility and outcomes. Unlike NESHIE, for which a limited number of genetic studies have been performed, many studies have identified genetic variants associated with cerebral palsy (CP), which can develop from severe NESHIE. Identifying variants in patients with CP, as a consequence of NESHIE, may provide a starting point for the identification of genetic variants associated with NESHIE outcomes. We have constructed NCGR (NESHIE and CP Genetics Resource), a database of genes and variants reported in patients with NESHIE and CP (where relevant to NESHIE), for the purpose of collating and comparing genetic findings between the two conditions. In this paper we describe the construction and functionality of NCGR. Furthermore, we demonstrate how NCGR can be used to prioritise genes and variants of potential clinical relevance that may underlie a genetic predisposition to NESHIE and contribute to an understanding of its pathogenesis.

Relationship Between TNF-α and the Risk of Cerebral Palsy: A Systematic Review and Meta-Analysis

Objective

We performed a meta-analysis to investigate the relationship between blood tumor necrosis factor-alpha (TNF-α) levels and the risk of cerebral palsy (CP) in children.

Methods

PubMed, Web of Science, Cochrane Library and Ovid databases were searched from the date of database inception to 26 April 2022. Data were extracted and pooled from observational studies related to TNF-α and the risk of CP in children. Quality was assessed using the Newcastle-Ottawa Scale. We used the inverse variance method with a random-effects model to estimate the odds ratios with 95% confidence intervals (CIs), and stratified analyses and sensitivity analysis were utilized to analyse heterogeneity.

Results

Nine studies with 1,117 cases and 3,563 controls were included in our meta-analysis. The quality of the literature was good, and no publication bias was noted. According to the random-effects model, blood TNF-α levels were associated with the risk of CP (OR 1.82; 95% CI, 1.25–2.66) in a heterogeneous set of studies (I2 = 81.2%, p = 0.000).

Conclusion

Our findings indicate that elevated TNF-α levels in the blood are associated with an increased risk of CP. The association of TNF-α with CP requires further investigation.

Sex-specific cytokine responses and neurocognitive outcome after blood transfusions in preterm infants

BACKGROUND

The objective of this study was to determine sex-specific differences in inflammatory cytokine responses to red blood cell (RBC) transfusion in preterm infants in the neonatal period and their relationship to later neurocognitive status.

METHODS

Infants with a birth weight <1000 g and gestational age 22-29 weeks were enrolled in the Transfusion of Prematures (TOP) trial. The total number of transfusions was used as a marker of transfusion status. Nineteen cytokines and biomarkers were analyzed from 71 infants longitudinally during the neonatal period. Twenty-six infants completed the Bayley Scales of Infant & Toddler Development, 3rd Edition (Bayley-III) at 12 months' corrected age.

RESULTS

Nine cytokine levels were significantly elevated in proportion to the number of transfusions received. Of those, one cytokine showed a sex-specific finding (p = 0.004): monocyte chemoattractant protein-1, MCP-1, rose substantially in females (8.9% change per additional transfusion), but not in males (-0.8% change). Higher concentrations of MCP-1 exclusively were associated with worse Bayley-III scores: decreased cognitive raw scores (p = 0.0005) and motor scaled scores (p < 0.0001).

CONCLUSIONS

This study provides evidence of a sex-specific difference in the inflammatory response to RBC transfusions during neonatal life, with MCP-1 levels rising only in females and inversely correlating with neurocognitive status at 12 months old.

IMPACT

It is important to understand the risk factors for abnormal neurodevelopment in preterm infants, including anemia and RBC transfusion, in order to improve outcomes and provide potential targets for therapy. Our study investigates and provides the first evidence of sex-specific differences in inflammatory cytokine responses to RBC transfusions in preterm infants in the neonatal period, and their relationship to later cognitive outcomes. This study critically suggests that different transfusion thresholds may have a sex-specific effect on neurodevelopment: females have worse cognitive outcomes with increased number of transfusions, while males have worse outcomes with lower number of transfusions.

South Indian children's neurodevelopmental outcomes after Group B Streptococcus invasive disease: A case cohort study

Background

This study is part of a multicountry matched-cohort study designed to estimate the risk of long-term neurodevelopmental impairment (NDI) of children exposed to invasive group B Streptococcus (iGBS). The specific objective of this paper is to compare NDI across domains of iGBS survivors with a matched non iGBS group in our population.

Methods

Survivors of iGBS in a South Indian hospital were identified and recruited between January 2020 and April 2021. Cases were compared with age- and gender-matched non iGBS children. Participants were assessed using Bayley Scales of Infant and Toddler Development–3rd edition (BSID-III), Wechsler Preschool and Primary Scale of Intelligence–4th edition (WPPSI-IV), Wechsler Intelligence Scale for Children–5th edition (WISC-V), Child Behavior Checklist (CBCL), and Bruininks-Oseretsky Test of Motor Proficiency, 2nd edition (BOT-2), depending on age.

Results

Our cohort comprised 35 GBS-exposed and 65 matched non iGBS children, aged 1–14 years. The iGBS-exposed group had 17 (48.6%) children with impairment in ≥1 domain compared to 25 (38%) in the non iGBS group (unadjusted OR, 1.51; 95% CI, .65–3.46), 9 (26%) children with “multi-domain impairment” compared to 10 (15.4%) in the non iGBS group (unadjusted OR, 1.90; 95% CI, .69–5.24), and 1 (2.9%) child with moderate to severe impairment compared to 3 (4.6%) in the non iGBS group (unadjusted OR, .60; 95% CI, .06–6.07). In the iGBS group, more children had motor impairments compared with the non iGBS group (unadjusted OR, 10.7; 95% CI, 1.19–95.69; P = .034).

Conclusions

Children with iGBS seem at higher risk of developing motor impairments compared with a non iGBS group.

The Role of Neuroimaging and Genetic Analysis in the Diagnosis of Children With Cerebral Palsy

Cerebral magnetic resonance imaging (MRI) is considered an important tool in the assessment of a child with cerebral palsy (CP), as it is abnormal in more than 80% of children with CP, disclosing the pathogenic pattern responsible for the neurological condition. MRI, therefore, is recommended as the first diagnostic step after medical history taking and neurological examination. With the advances in genetic diagnostics, the genetic contribution to CP is increasingly discussed, and the question arises about the role of genetic testing in the diagnosis of cerebral palsy. The paper gives an overview on genetic findings reported in CP, which are discussed with respect to the underlying brain pathology according to neuroimaging findings. Surveillance of Cerebral Palsy in Europe (SCPE) classifies neuroimaging findings in CP into five categories, which help to stratify decisions concerning genetic testing. Predominant white and gray matter injuries are by far predominant (accounting for around 50 and 20% of the findings). They are considered to be acquired. Here, predisposing genetic factors may play a role to increase vulnerability (and should especially be considered, when family history is positive and/or causative external factors are missing). In maldevelopments and normal findings (around 11% each), monogenic causes are more likely, and thus, genetic testing is clearly recommended. In the miscellaneous category, the precise nature of the MRI finding has to be considered as it could indicate a genetic origin.

Genetic Factors of Nitric Oxide's System in Psychoneurologic Disorders

According to the recent data, nitric oxide (NO) is a chemical messenger that mediates functions such as vasodilation and neurotransmission, as well as displaying antimicrobial and antitumoral activities. NO has been implicated in the neurotoxicity associated with stroke and neurodegenerative diseases; neural regulation of smooth muscle, including peristalsis; and penile erections. We searched for full-text English publications from the past 15 years in Pubmed and SNPedia databases using keywords and combined word searches (nitric oxide, single nucleotide variants, single nucleotide polymorphisms, genes). In addition, earlier publications of historical interest were included in the review. In our review, we have summarized information regarding all NOS1, NOS2, NOS3, and NOS1AP single nucleotide variants (SNVs) involved in the development of mental disorders and neurological diseases/conditions. The results of the studies we have discussed in this review are contradictory, which might be due to different designs of the studies, small sample sizes in some of them, and different social and geographical characteristics. However, the contribution of genetic and environmental factors has been understudied, which makes this issue increasingly important for researchers as the understanding of these mechanisms can support a search for new approaches to pathogenetic and disease-modifying treatment.

Sex-Specific Genetic Susceptibility to Adverse Neurodevelopmental Outcome in Offspring of Pregnancies at Risk of Early Preterm Delivery

OBJECTIVE

To evaluate sex-specific genetic susceptibility to adverse neurodevelopmental outcome (ANO, defined as cerebral palsy [CP], mental, or psychomotor delay) at risk for early preterm birth (EPTB, < 32 weeks).

STUDY DESIGN

Secondary case-control analysis of a trial of magnesium sulfate (MgSO4) before anticipated EPTB for CP prevention. Cases are infants who died by the age of 1 year or developed ANO. Controls, matched by maternal race and infant sex, were neurodevelopmentally normal survivors. Neonatal DNA was evaluated for 80 polymorphisms in inflammation, coagulation, vasoregulation, excitotoxicity, and oxidative stress pathways using Taqman assays. The primary outcome for this analysis was sex-specific ANO susceptibility. Conditional logistic regression estimated each polymorphism's odds ratio (OR) by sex stratum, adjusting for gestational age, maternal education, and MgSO4-corticosteroid exposures. Holm-Bonferroni corrections, adjusting for multiple comparisons (p < 7.3 × 10-4), accounted for linkage disequilibrium between markers.

RESULTS

Analysis included 211 cases (134 males; 77 females) and 213 controls (130 males; 83 females). An interleukin-6 (IL6) polymorphism (rs2069840) was associated with ANO in females (OR: 2.6, 95% confidence interval [CI]: 1.5-4.7; p = 0.001), but not in males (OR: 0.8, 95% CI: 0.5-1.2; p = 0.33). The sex-specific effect difference was significant (p = 7.0 × 10-4) and was unaffected by MgSO4 exposure. No other gene-sex associations were significant.

CONCLUSION

An IL6 gene locus may confer susceptibility to ANO in females, but not males, after EPTB.

Glutamate Transport and Preterm Brain Injury

Preterm birth complications are the leading cause of child death worldwide and a top global health priority. Among the survivors, the risk of life-long disabilities is high, including cerebral palsy and impairment of movement, cognition, and behavior. Understanding the molecular mechanisms of preterm brain injuries is at the core of future healthcare improvements. Glutamate excitotoxicity is a key mechanism in preterm brain injury, whereby the accumulation of extracellular glutamate damages the delicate immature oligodendrocytes and neurons, leading to the typical patterns of injury seen in the periventricular white matter. Glutamate excitotoxicity is thought to be induced by an interaction between environmental triggers of injury in the perinatal period, particularly cerebral hypoxia-ischemia and infection/inflammation, and developmental and genetic vulnerabilities. To avoid extracellular build-up of glutamate, the brain relies on rapid uptake by sodium-dependent glutamate transporters. Astrocytic excitatory amino acid transporter 2 (EAAT2) is responsible for up to 95% of glutamate clearance, and several lines of evidence suggest that it is essential for brain functioning. While in the adult EAAT2 is predominantly expressed by astrocytes, EAAT2 is transiently upregulated in the immature oligodendrocytes and selected neuronal populations during mid-late gestation, at the peak time for preterm brain injury. This developmental upregulation may interact with perinatal hypoxia-ischemia and infection/inflammation and contribute to the selective vulnerability of the immature oligodendrocytes and neurons in the preterm brain. Disruption of EAAT2 may involve not only altered expression but also impaired function with reversal of transport direction. Importantly, elevated EAAT2 levels have been found in the reactive astrocytes and macrophages of human infant post-mortem brains with severe white matter injury (cystic periventricular leukomalacia), potentially suggesting an adaptive mechanism against excitotoxicity. Interestingly, EAAT2 is suppressed in animal models of acute hypoxic-ischemic brain injury at term, pointing to an important and complex role in newborn brain injuries. Enhancement of EAAT2 expression and transport function is gathering attention as a potential therapeutic approach for a variety of adult disorders and awaits exploration in the context of the preterm brain injuries.

Meta-Analysis of Factor V, Factor VII, Factor XII, and Factor XIII-A Gene Polymorphisms and Ischemic Stroke

Numerous studies examined the association between factors FV, FVII, FXII, and FXIII-A gene polymorphisms and ischemic stroke, but conclusive evidence is yet to be obtained. Thus, this meta-analysis aimed to investigate the novel association of FV rs1800595, FVII rs5742910, FXII rs1801020, and FXIII-A rs5982 and rs3024477 polymorphisms with ischemic stroke risk. A systematic review was performed on articles retrieved before June 2018. Relevant data were extracted from eligible studies and meta-analyzed using RevMan version 5.3. The strength of association between studied polymorphisms and ischemic stroke risk was calculated as odds ratios and 95% confidence intervals, by applying both fixed- and random-effect models. A total of 25 studies involving 6100 ischemic stroke patients and 9249 healthy controls were incorporated in the final meta-analysis model. Specifically, rs1800595, rs5742910, rs1801020, rs5982, and rs3024477 consisted of 673, 3668, 922, 433, and 404 cases, as well as 995, 4331, 1285, 1321, and 1317 controls, respectively. The pooled analysis indicated that there was no significant association of FV rs1800595, FVII rs5742910, FXII rs1801020, FXIII-A rs5982, and FXIII-A rs3024477 polymorphisms with ischemic stroke risk, under any genetic models (dominant, recessive, over-dominant, and allelic). The present meta-analysis concluded that FV rs1800595, FVII rs5742910, FXII rs1801020, and FXIII-A rs5982 and rs3024477 polymorphisms are not associated with ischemic stroke risk.

Genetic Variation, Magnesium Sulfate Exposure, and Adverse Neurodevelopmental Outcomes Following Preterm Birth

OBJECTIVE

To evaluate the association of magnesium sulfate (MgSO4) exposure and candidate gene polymorphisms with adverse neurodevelopmental outcomes following preterm birth.

STUDY DESIGN

We performed a nested case-control analysis of a randomized trial of maternal MgSO4 before anticipated preterm birth for the prevention of cerebral palsy (CP). Cases were children who died within 1 year of life or were survivors with abnormal neurodevelopment at age 2 years. Controls were race- and sex-matched survivors with normal neurodevelopment. We analyzed 45 candidate gene polymorphisms in inflammation, coagulation, and vascular regulation pathways and their association with (1) psychomotor delay, (2) mental delay, (3) CP, and (4) combined outcome of death/CP. Logistic regression analyses, conditional on maternal race and child sex, and adjusted for treatment group, gestational age at birth and maternal education, were performed.

RESULTS

Four hundred and six subjects, 211 cases and 195 controls, were analyzed. The strongest association was for IL6R (rs 4601580) in which each additional copy of the minor allele was associated with an increased risk of psychomotor delay (adjusted odds ratio 3.3; 95% confidence interval, 1.7-6.5; p < 0.001).

CONCLUSION

Candidate gene polymorphisms are associated with death and adverse neurodevelopmental outcomes following preterm birth. MgSO4 may abrogate this genotype association for some loci.

De novo and rare inherited copy-number variations in the hemiplegic form of cerebral palsy

Purpose

Hemiplegia is a subtype of cerebral palsy (CP) in which one side of the body is affected. Our earlier study of unselected children with CP demonstrated de novo and clinically relevant rare inherited genomic copy-number variations (CNVs) in 9.6% of participants. Here, we examined the prevalence and types of CNVs specifically in hemiplegic CP.

Methods

We genotyped 97 unrelated probands with hemiplegic CP and their parents. We compared their CNVs to those of 10,851 population controls, in order to identify rare CNVs (<0.1% frequency) that might be relevant to CP. We also sequenced exomes of “CNV-positive” trios.

Results

We detected de novo CNVs and/or sex chromosome abnormalities in 7/97 (7.2%) of probands, impacting important developmental genes such as GRIK2, LAMA1, DMD, PTPRM, and DIP2C. In 18/97 individuals (18.6%), rare inherited CNVs were found, affecting loci associated with known genomic disorders (17p12, 22q11.21) or involving genes linked to neurodevelopmental disorders.

Conclusion

We found an increased rate of de novo CNVs in the hemiplegic CP subtype (7.2%) compared to controls (1%). This result is similar to that for an unselected CP group. Combined with rare inherited CNVs, the genomic data impacts the understanding of the potential etiology of hemiplegic CP in 23/97 (23.7%) of participants.

The genetic basis of cerebral palsy

Although prematurity and hypoxic-ischaemic injury are well-recognized contributors to the pathogenesis of cerebral palsy (CP), as many as one-third of children with CP may lack traditional risk factors. For many of these children, a genetic basis to their condition is suspected. Recent findings have implicated copy number variants and mutations in single genes in children with CP. Current studies are limited by relatively small patient numbers, the underlying genetic heterogeneity identified, and the paucity of validation studies that have been performed. However, several genes mapping to intersecting pathways controlling neurodevelopment and neuronal connectivity have been identified. Analogous to other neurodevelopmental disorders such as autism and intellectual disability, the genomic architecture of CP is likely to be highly complex. Although we are just beginning to understand genetic contributions to CP, new insights are anticipated to serve as a unique window into the neurobiology of CP and suggest new targets for intervention.

Interleukin-6 promoter polymorphism interacts with pain and life stress influencing depression phenotypes

Interleukin-6 (IL-6) has emerged as a potent biomarker for depression as its elevated plasma levels in patients with clinical depression have been confirmed by meta-analyses. Increased plasma IL-6 concentration was associated with various psychological stress factors and physical disorders accompanied by pain. Another modulator of the IL-6 level is rs1800795, a promoter polymorphism in the IL-6 gene which is able to influence its expression rate. Therefore, we examined in a Hungarian population sample of 1053 volunteers with European origins if rs1800795 polymorphism can affect depression symptoms measured by Zung Self-rating Depression Scale (ZSDS), and Brief Symptom Inventory (BSI). We also investigated the interactions of the polymorphism with reported painful physical conditions and Recent Negative Life Events (RLE) measured by the List of Life Threatening Experiences. Rs1800795 significantly interacted with both RLE and painful condition on depressive symptoms measured by ZSDS and BSI using different heritability models, while no main effects of the polymorphism were identified. After correction for multiple testing only the rs1800795 × RLE interaction effect (recessive model) remained significant on the BSI score, while both RLE and painful conditions significantly interacted on the ZSDS. In conclusion, the functional IL-6 rs1800795 polymorphism in interaction with various stress factors increases the risk of depression and has a greater impact on symptoms measured by the ZSDS. Thus, IL-6 and other cytokines may be more relevant in the development of somatic symptoms compared to affective signs of depression, delineating a specific genotype–phenotype relationship in this heterogeneous disorder.

Plasma Tumor Necrosis Factor-alpha (TNF-α) Levels Correlate with Disease Severity in Spastic Diplegia, Triplegia, and Quadriplegia in Children with Cerebral Palsy

Background

Inflammatory responses in utero and in neonates have been involved in the development of white matter lesions. This study aimed to investigate the role of tumor necrosis factor-alpha (TNF-α) in spastic cerebral palsy.

Material/Methods

Plasma TNF-α was measured by ELISA in 54 children with spastic cerebral palsy and 28 aged-matched controls. Both groups were split into age subgroups (1–3 vs. 4–12). Gross motor function and activities of daily living were assessed on enrollment and after 6 months of rehabilitation.

Results

TNF-α was higher in patients with cerebral palsy than in controls in young (P<0.001) and older subjects (P<0.001). TNF-α levels were comparable in both control subgroups (P=0.819). Younger patients with cerebral palsy had significantly higher TNF-α levels compared with older ones (P<0.001). Pre-rehabilitation TNF-α levels correlated with improvements in activities of daily living after rehabilitation (P<0.001).

Conclusions

Children with cerebral palsy showed higher plasma levels of TNF-α than controls. In addition, pre-treatment TNF-α levels were correlated with the improvements after rehabilitation therapy.

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.

A systematic appraisal of field synopses in genetic epidemiology: a HuGE review

Evidence from genetic association studies is accumulating rapidly. Field synopses have recently arisen as an unbiased way of systematically synthesizing this evidence. We performed a systematic review and appraisal of published field synopses in genetic epidemiology and assessed their main findings and methodological characteristics. We identified 61 eligible field synopses, published between January 1, 2007, and October 31, 2013, on 52 outcomes reporting 734 significant associations at the P < 0.05 level. The median odds ratio for these associations was 1.25 (interquartile range, 1.15-1.43). Egger's test was the most common method (n = 30 synopses) of assessing publication bias. Only 12 synopses (20%) used the Venice criteria to evaluate the epidemiologic credibility of their findings (n = 449 variants). Eleven synopses (18%) were accompanied by an online database that has been regularly updated. These synopses received more citations (P = 0.01) and needed a larger research team (P = 0.02) than synopses without an online database. Overall, field synopses are becoming a valuable tool for the identification of common genetic variants, especially when researchers follow relevant methodological guidelines. Our work provides a summary of the current status of the field synopses published to date and may help interested readers efficiently identify the online resources containing the relevant genetic evidence.

Mutations in γ adducin are associated with inherited cerebral palsy

OBJECTIVE

Cerebral palsy is estimated to affect nearly 1 in 500 children, and although prenatal and perinatal contributors have been well characterized, at least 20% of cases are believed to be inherited. Previous studies have identified mutations in the actin-capping protein KANK1 and the adaptor protein-4 complex in forms of inherited cerebral palsy, suggesting a role for components of the dynamic cytoskeleton in the genesis of the disease.

METHODS

We studied a multiplex consanguineous Jordanian family by homozygosity mapping and exome sequencing, then used patient-derived fibroblasts to examine functional consequences of the mutation we identified in vitro. We subsequently studied the effects of adducin loss of function in Drosophila.

RESULTS

We identified a homozygous c.1100G>A (p.G367D) mutation in ADD3, encoding gamma adducin in all affected members of the index family. Follow-up experiments in patient fibroblasts found that the p.G367D mutation, which occurs within the putative oligomerization critical region, impairs the ability of gamma adducin to associate with the alpha subunit. This mutation impairs the normal actin-capping function of adducin, leading to both abnormal proliferation and migration in cultured patient fibroblasts. Loss of function studies of the Drosophila adducin ortholog hts confirmed a critical role for adducin in locomotion.

INTERPRETATION

Although likely a rare cause of cerebral palsy, our findings indicate a critical role for adducins in regulating the activity of the actin cytoskeleton, suggesting that impaired adducin function may lead to neuromotor impairment and further implicating abnormalities of the dynamic cytoskeleton as a pathogenic mechanism contributing to cerebral palsy.

Sequencing of the IL6 gene in a case-control study of cerebral palsy in children

Background

Cerebral palsy (CP) is a group of nonprogressive disorders of movement and posture caused by abnormal development of, or damage to, motor control centers of the brain. A single nucleotide polymorphism (SNP), rs1800795, in the promoter region of the interleukin-6 (IL6) gene has been implicated in the pathogenesis of CP by mediating IL-6 protein levels in amniotic fluid and cord plasma and within brain lesions. This SNP has been associated with other neurological, vascular, and malignant processes as well, often as part of a haplotype block.

Methods

To refine the regional genetic association with CP, we sequenced (Sanger) the IL6 gene and part of the promoter region in 250 infants with CP and 305 controls.

Results

We identified a haplotype of 7 SNPs that includes rs1800795. In a recessive model of inheritance, the variant haplotype conferred greater risk (OR = 4.3, CI = [2.0-10.1], p = 0.00007) than did the lone variant at rs1800795 (OR = 2.5, CI = [1.4-4.6], p = 0.002). The risk haplotype contains one SNP (rs2069845, CI = [1.2-4.3], OR = 2.3, p = 0.009) that disrupts a methylation site.

Conclusions

The risk haplotype identified in this study overlaps with previously identified haplotypes that include additional promoter SNPs. A risk haplotype at the IL6 gene likely confers risk to CP, and perhaps other diseases, via a multi-factorial mechanism.

Genetic and clinical contributions to cerebral palsy: a multi-variable analysis

AIM

This study aims to examine single nucleotide polymorphism (SNP) associations with cerebral palsy in a multi-variable analysis adjusting for potential clinical confounders and to assess SNP-SNP and SNP-maternal infection interactions as contributors to cerebral palsy.

METHODS

A case control study including 587 children with cerebral palsy and 1154 control children without cerebral palsy. Thirty-nine candidate SNPs were genotyped in both mother and child. Data linkage to perinatal notes and cerebral palsy registers was performed with a supplementary maternal pregnancy questionnaire. History of known maternal infection during pregnancy was extracted from perinatal databases.

RESULTS

Both maternal and fetal carriage of inducible nitric oxide synthase SNP rs1137933 were significantly negatively associated with cerebral palsy in infants born at less than 32 weeks gestation after adjustment for potential clinical confounders and correction for multiple testing (odds ratio 0.55, 95% confidence interval 0.38-0.79; odds ratio 0.57, 95% confidence interval 0.4-0.82, respectively). Analysis did not show any statistically significant SNP-SNP or SNP-maternal infection interactions after correction for multiple testing.

CONCLUSIONS

Maternal and child inducible nitric oxide synthase SNPs are associated with reduced risk of cerebral palsy in infants born very preterm. There was no evidence for statistically significant SNP-SNP or SNP-maternal infection interactions as modulators of cerebral palsy risk.

Association of Interleukin 6 gene polymorphisms with genetic susceptibilities to spastic tetraplegia in males: a case-control study

BACKGROUND

Cerebral palsy (CP) is a group of non-progressive motor impairment and permanent disorders causing limitation of activity and abnormal posture. It may be caused by infection (such as chorioamnionitis), asphyxia or multiple genetic factors. The Interleukin 6 gene (IL6) was suggested to be involved in the susceptibilities to CP risk as a kind of proinflammatory cytokine.

OBJECTIVE

To explore the genetic association between the polymorphisms of the IL6 gene and CP in the Chinese population.

METHODS

A total of 542 CP patients and 483 healthy control children were recruited in this study to detect five single nucleotide polymorphisms (rs1800796, rs2069837, rs2066992, rs2069840, and rs10242595) in the IL6 locus. Genotyping of SNPs was performed by the MassArray platform-based genotyping approach. The SHEsis program was applied to analyze the genotyping data.

RESULTS

Of the five selected SNPs, no significant allelic and genotypic association was found between CP patients and controls. However, subgroup analysis found significant differences in allele frequencies between spastic tetraplegia in males compared with controls at rs1800796 (OR=1.39, P=0.033, P=0.099 after SNPSpD correction) and rs2069837 (OR=1.58, P=0.012, P=0.035 after SNPSpD correction). The frequencies of the C allele of rs1800796 and the A allele of rs2069837 were greater in males with spastic tetraplegia than in the controls. The two SNPs haplotype rs1800796 (G) - rs2069837 (G) were also associated with a decreased risk of spastic tetraplegia in males (OR=0.619, P=0.009, P=0.027 after Bonferroni correction).

CONCLUSION

Genetic variation of the IL6 gene may influence susceptibility to spastic tetraplegia in males and its role in cerebral palsy deserves further evaluation in a large-scale and well-designed study.

Genetic risk factors for perinatal arterial ischemic stroke

The cause of perinatal arterial ischemic stroke is unknown in most cases. We explored whether genetic polymorphisms modify the risk of perinatal arterial ischemic stroke. In a population-based case-control study of 1997-2002 births at Kaiser Permanente Northern California, we identified 13 white infants with perinatal arterial ischemic stroke. Control subjects included 86 randomly selected white infants. We genotyped polymorphisms in nine genes involved in inflammation, thrombosis, or lipid metabolism previously linked with stroke, and compared genotype frequencies in case and control individuals. We tested several polymorphisms: tumor necrosis factor-α -308, interleukin-6, lymphotoxin A, factor V Leiden, methyltetrahydrofolate reductase 1298 and 667, prothrombin 20210, and apolipoprotein E ε2 and ε4 alleles. Patients with perinatal arterial ischemic stroke were more likely than control subjects to demonstrate at least one apolipoprotein E ε4 allele (54% vs 25%, P = 0.03). More patients with perinatal arterial ischemic stroke carried two ε4 alleles than did control subjects (15% vs 2%, P = 0.09), although this finding lacked statistical significance. Proinflammatory and prothrombotic polymorphisms were not associated with perinatal arterial ischemic stroke. The apolipoprotein E polymorphism may confer genetic susceptibility for perinatal arterial ischemic stroke. Larger population-based studies are required to confirm this finding.

The interleukin-6 -174G/C polymorphism and prostate cancer risk: a systematic review and meta-analysis

OBJECTIVE

This systematic review and meta-analysis was undertaken to integrate previous findings and summarize the effect size of the association of interleukin-6 (IL-6) genetic polymorphism -174G/C with susceptibility to prostate cancer (PCa).

METHODS

All eligible studies of IL-6 -174G/C polymorphism and PCa risk were collected from the following electronic databases: PubMed and the Cochrane Library, with the last report up to June 1, 2011. Statistical analyses were performed by Review Manage version 5.0 and Stata 10.0.

RESULTS

A total of 7 independent studies, including 9,959 cases and 12,361 controls, were identified. When all studies were pooled, we did not detect a significant association of -174G/C polymorphism with PCa risk. When stratifying for race, similar results were obtained; evidence of a significant relation was absent in both Caucasians and the mixed population. After stratifying the studies by study types, -174G/C polymorphism was significantly associated with PCa risk when examining the contrast of CC + GC versus GG (OR = 1.44, 95% CI = 1.05-1.98, p = 0.03) in cohort studies but not in case-control studies.

CONCLUSIONS

Our review suggest that -174G/C polymorphism is associated with an increased PCa risk in two cohort studies from one article. Additional well-designed studies are warranted to validate these findings.

The role of cytokines and inflammatory cells in perinatal brain injury

Perinatal brain injury frequently complicates preterm birth and leads to significant long-term morbidity. Cytokines and inflammatory cells are mediators in the common pathways associated with perinatal brain injury induced by a variety of insults, such as hypoxic-ischemic injury, reperfusion injury, toxin-mediated injury, and infection. This paper examines our current knowledge regarding cytokine-related perinatal brain injury and specifically discusses strategies for attenuating cytokine-mediated brain damage.

Genetic [corrected] insights into the causes and classification of [corrected] cerebral palsies

Cerebral palsy-the most common physical disability of childhood-is a clinical diagnosis encompassing a heterogeneous group of neurodevelopmental disorders that cause impairments of movement and posture that persist throughout life. Despite being commonly attributed to a range of environmental factors, particularly birth asphyxia, the specific cause of cerebral palsy remains unknown in most individuals. A growing body of evidence suggests that cerebral palsy is probably caused by multiple genetic factors, similar to other neurodevelopmental disorders such as autism and intellectual disability. Recent advances in next-generation sequencing technologies have made possible rapid and cost-effective sequencing of the entire human genome. Novel cerebral palsy genes will probably be identified as more researchers and clinicians use this approach to study individuals with undiagnosed neurological disorders. As our knowledge of the underlying pathophysiological mechanisms of cerebral palsy increases, so will the possibility of developing genomically guided therapeutic interventions.

Candidate genes and risk for CP: a population-based study

Studies suggest that genetic polymorphisms may increase an individual's susceptibility to CP. Most findings have yet to be corroborated in an independent cohort. This case-control study is nested within all 334,333 infants ≥36 wk gestation born at Kaiser Permanente Medical Care Program, 1991-2002. We included only non-Hispanic whites who had a neonatal blood sample available. Case patients (n = 138) were identified from medical records to have spastic or dyskinetic CP. Controls (n = 165) were randomly selected from the population. We genotyped polymorphisms previously associated with CP: inducible NOS (iNOS)-231, apolipoprotein E (apoE) ε2 and ε4 alleles, TNF-α-308, IL-8 -251, lymphotoxin 60, endothelial NOS -922, endothelial protein C receptor 219, mannose-binding lectin 54 and 52, factor V Leiden, methyltetrahydrofolate reductase 1298 and 667, prothrombin 20210, and platelet activator inhibitor 11053. Similar to previous reports, the iNOS-231 T allele (25.7 versus 18.9%, p = 0.04) and the apoE ε4 allele (19.3 versus 13.2%, p = 0.04) were more common in patients with CP than in controls. However, there was no statistically significant association between any genetic polymorphism and CP after correction for multiple comparisons.