Association of polymorphisms in neuroprotection and oxidative stress genes and neurodevelopmental outcomes after preterm birth

High protein intake on later outcomes in preterm children: a systematic review and meta-analysis

BACKGROUND

Appropriate protein intake is crucial for growth and development in children born preterm. We assessed the effects of high (HP) versus low protein (LP) intake on neurodevelopment, growth, and biochemical anomalies in these children.

METHODS

Randomised and quasi-randomised trials providing protein to children born preterm (<37 completed weeks of gestation) were searched following PRISMA guideline in three databases and four registers (PROSPERO registration CRD42022325659). Random-effects model was used for assessing the effects of HP (≥3.5 g/kg/d) vs. LP (<3.5 g/kg/d).

RESULTS

Data from forty-four studies (n = 5338) showed HP might slightly reduce the chance of survival without neurodisability at ≥12 months (four studies, 1109 children, relative risk [RR] 0.95 [95% CI 0.90, 1.01]; P = 0.13; low certainty evidence) and might increase risk of cognitive impairment at toddler age (two studies; 436 children; RR 1.36 [0.89, 2.09]; P = 0.16; low certainty evidence). At discharge or 36 weeks, HP intake might result in higher weight and greater head circumference z-scores. HP intake probably increased the risk of hypophosphatemia, hypercalcemia, refeeding syndrome and high blood urea, but reduced risk of hyperglycaemia.

CONCLUSIONS

HP intake for children born preterm may be harmful for neonatal metabolism and later neurodisability and has few short-term benefits for growth.

IMPACT STATEMENT

Planned high protein intake after birth for infants born preterm might be harmful for survival, neurodisability and metabolism during infancy and did not improve growth after the neonatal period. Protein intake ≥3.5 g/kg/d should not be recommended for children born preterm.

Metformin attenuates white matter injury in neonatal mice through activating NRF2/HO-1/NF-κB pathway

White matter injury (WMI) is a major form of brain injury that occurs in preterm infants and develops into lifelong disabilities, including cerebral palsy, impaired cognitive function, and psychiatric disorders. Metformin (MET) has been reported to have neuroprotective effects. However, whether MET is responsible for neuroprotection against WMI remains unclear. In this study, we established a WMI model in neonatal mice to explore the neuroprotective effects of MET and attempted to elucidate its potential mechanisms. Our results showed that MET increased the expression of myelin basic protein (MBP), oligodendrocyte transcription factor 2 (Olig2), and CC1, improved the thickness and density of the myelin sheath, and reduced oxidative stress and microglial infiltration after chronic hypoxia induction. Moreover, MET improved memory, learning, and motor abilities as well as relieved anxiety-like behaviors in mice with WMI. These protective effects of MET may involve the upregulation of the nuclear factor erythroid 2-related factor 2 (NRF2)/heme oxygenase-1(HO-1)/NF-κB pathway related protein expressions. In addition, the NRF2 inhibitor ML385 could significantly reverse the effects of MET. In conclusion, this study suggested that MET attenuated chronic hypoxia-induced WMI through activating the NRF2/HO-1/NF-κB pathway, indicating that MET might be a promising therapeutic option for WMI.

Genetic Predisposition to Adverse Neurodevelopmental Outcome of Extremely Low Birth Weight Infants

OBJECTIVE

This study aimed to evaluate whether there are genetic variants associated with adverse neurodevelopmental outcomes in extremely low birth weight (ELBW) infants.

STUDY DESIGN

We conducted a candidate gene association study in two well-defined cohorts of ELBW infants (<1,000 g). One cohort was for discovery and the other for replication. The discovery case-control analysis utilized anonymized DNA samples and evaluated 1,614 single-nucleotide polymorphisms (SNPs) in 145 genes concentrated in inflammation, angiogenesis, brain development, and oxidation pathways. Cases were children who died by age one or who were diagnosed with cerebral palsy (CP) or neurodevelopmental delay (Bayley II mental developmental index [MDI] or psychomotor developmental index [PDI] < 70) by 18 to 22 months. Controls were survivors with normal neurodevelopment. We assessed significant epidemiological variables and SNPs associated with the combined outcome of CP or death, CP, mental delay (MDI < 70) and motor delay (PDI < 70). Multivariable analyses adjusted for gestational age at birth, small for gestational age, sex, antenatal corticosteroids, multiple gestation, racial admixture, and multiple comparisons. SNPs associated with adverse neurodevelopmental outcomes with p < 0.01 were selected for validation in the replication cohort. Successful replication was defined as p < 0.05 in the replication cohort.

RESULTS

Of 1,013 infants analyzed (452 cases, 561 controls) in the discovery cohort, 917 were successfully genotyped for >90% of SNPs and passed quality metrics. After adjusting for covariates, 26 SNPs with p < 0.01 for one or more outcomes were selected for replication cohort validation, which included 362 infants (170 cases and 192 controls). A variant in SERPINE1, which encodes plasminogen activator inhibitor (PAI1), was associated with the combined outcome of CP or death in the discovery analysis (p = 4.1 × 10-4) and was significantly associated with CP or death in the replication cohort (adjusted odd ratio: 0.4; 95% confidence interval: 0.2-1.0; p = 0.039).

CONCLUSION

A genetic variant in SERPINE1, involved in inflammation and coagulation, is associated with CP or death among ELBW infants.

KEY POINTS

· Early preterm and ELBW infants have dramatically increased risks of CP and developmental delay.. · A genetic variant in SERPINE1 is associated with CP or death among ELBW infants.. · The SERPINE1 gene encodes the serine protease inhibitor plasminogen activator inhibitor..

Modeling sex differences in humans using isogenic induced pluripotent stem cells

Biological sex is a fundamental trait influencing development, reproduction, pathogenesis, and medical treatment outcomes. Modeling sex differences is challenging because of the masking effect of genetic variability and the hurdle of differentiating chromosomal versus hormonal effects. In this work we developed a cellular model to study sex differences in humans. Somatic cells from a mosaic Klinefelter syndrome patient were reprogrammed to generate isogenic induced pluripotent stem cell (iPSC) lines with different sex chromosome complements: 47,XXY/46,XX/46,XY/45,X0. Transcriptional analysis of the hiPSCs revealed novel and known genes and pathways that are sexually dimorphic in the pluripotent state and during early neural development. Female hiPSCs more closely resembled the naive pluripotent state than their male counterparts. Moreover, the system enabled differentiation between the contributions of X versus Y chromosome to these differences. Taken together, isogenic hiPSCs present a novel platform for studying sex differences in humans and bear potential to promote gender-specific medicine in the future.

Innovative computational approaches shed light on genetic mechanisms underlying cognitive impairment among children born extremely preterm

BACKGROUND

Although survival rates for infants born extremely preterm (gestation < 28 weeks) have improved significantly in recent decades, neurodevelopmental impairment remains a major concern. Children born extremely preterm remain at high risk for cognitive impairment from early childhood to adulthood. However, there is limited evidence on genetic factors associated with cognitive impairment in this population.

METHODS

First, we used a latent profile analysis (LPA) approach to characterize neurocognitive function at age 10 for children born extremely preterm. Children were classified into two groups: (1) no or low cognitive impairment, and (2) moderate-to-severe cognitive impairment. Second, we performed TOPMed-based genotype imputation on samples with genotype array data (n = 528). Third, we then conducted a genome-wide association study (GWAS) for LPA-inferred cognitive impairment. Finally, computational analysis was conducted to explore potential mechanisms underlying the variant x LPA association.

RESULTS

We identified two loci reaching genome-wide significance (p value < 5e-8): TEA domain transcription factor 4 (TEAD4 at rs11829294, p value = 2.40e-8) and syntaxin 18 (STX18 at rs79453226, p value = 1.91e-8). Integrative analysis with brain expression quantitative trait loci (eQTL), chromatin conformation, and epigenomic annotations suggests tetraspanin 9 (TSPAN9) and protein arginine methyltransferase 8 (PRMT8) as potential functional genes underlying the GWAS signal at the TEAD4 locus.

CONCLUSIONS

We conducted a novel computational analysis by utilizing an LPA-inferred phenotype with genetics data for the first time. This study suggests that rs11829294 and its LD buddies have potential regulatory roles on genes that could impact neurocognitive impairment for extreme preterm born children.

Differential Gene Expression in Cord Blood of Infants Diagnosed with Cerebral Palsy: A Pilot Analysis of the Beneficial Effects of Antenatal Magnesium Cohort

The Beneficial Effects of Antenatal Magnesium clinical trial was conducted between 1997 and 2007, and demonstrated a significant reduction in cerebral palsy (CP) in preterm infants who were exposed to peripartum magnesium sulfate (MgSO4). However, the mechanism by which MgSO4 confers neuroprotection remains incompletely understood. Cord blood samples from this study were interrogated during an era when next-generation sequencing was not widely accessible and few gene expression differences or biomarkers were identified between treatment groups. Our goal was to use bulk RNA deep sequencing to identify differentially expressed genes comparing the following four groups: newborns who ultimately developed CP treated with MgSO4 or placebo, and controls (newborns who ultimately did not develop CP) treated with MgSO4 or placebo. Those who died after birth were excluded. We found that MgSO4 upregulated expression of SCN5A only in the control group, with no change in gene expression in cord blood of newborns who ultimately developed CP. Regardless of MgSO4 exposure, expression of NPBWR1 and FTO was upregulated in cord blood of newborns who ultimately developed CP compared with controls. These data support that MgSO4 may not exert its neuroprotective effect through changes in gene expression. Moreover, NPBWR1 and FTO may be useful as biomarkers and may suggest new mechanistic pathways to pursue in understanding the pathogenesis of CP. The small number of cases ultimately available for this secondary analysis, with male predominance and mild CP phenotype, is a limitation of the study. In addition, differentially expressed genes were not validated by qRT-PCR.

GluN3A NMDA receptor subunits: more enigmatic than ever?

Non-conventional N-methyl-d-aspartate receptors (NMDARs) containing GluN3A subunits have unique biophysical, signalling and localization properties within the NMDAR family, and are typically thought to counterbalance functions of classical NMDARs made up of GluN1/2 subunits. Beyond their recognized roles in synapse refinement during postnatal development, recent evidence is building a wider perspective for GluN3A functions. Here we draw particular attention to the latest developments for this multifaceted and unusual subunit: from finely timed expression patterns that correlate with plasticity windows in developing brains or functional hierarchies in the mature brain to new insight onto presynaptic GluN3A-NMDARs, excitatory glycine receptors and behavioural impacts, alongside further connections to a range of brain disorders.

Polymorphisms in oxidative stress, metabolic detoxification, and immune function genes, maternal exposure to ambient air pollution, and risk of preterm birth in Taiyuan, China

Exposure to air pollutants may be associated with preterm birth (PB) through oxidative stress, metabolic detoxification, and immune system processes. However, no study has investigated the interactive effects of maternal air pollution and genetic polymorphisms in these pathways on risk of PB. The study included 126 PB and 310 term births. A total of 177 single nucleotide polymorphisms (SNPs) in oxidative stress, immune function, and metabolic detoxification-related genes were examined and analyzed. The China air quality index (AQI) was used as an overall estimation of ambient air pollutants. Among 177 SNPs, four SNPs (GPX4-rs376102, GLRX-rs889224, VEGFA-rs3025039, and IL1A-rs3783550) were found to have significant interactions with AQI on the risk of PB (P_interaction were 0.001, 0.003, 0.03, and 0.04, respectively). After being stratified by the maternal genotypes in these four SNPs, 1.38 to 1.76 times of the risk of PB were observed as per interquartile range increase in maternal AQI among women who carried the GPX4-rs376102 AC/CC genotypes, the GLRX-rs889224 TT genotype, the VEGFA-rs3025039 CC genotype, or the IL1A-rs3783550 GT/TT genotypes. After adjustment for multiple comparisons, only GPX4-rs376102 and AQI interaction remained statistically significant (false discovery rate (FDR)=0.17). After additional stratification by preeclampsia (PE) status, a strongest association was observed in women who carried the GPX4-rs376102 AC/CC genotypes (OR, 2.26; 95% CI, 1.41-3.65, P_interaction=0.0002, FDR=0.035) in the PE group. Our study provided the first evidence that association between maternal air pollution and PB risk may be modified by the genetic polymorphisms in oxidative stress and immune function genes. Future large studies are necessary to replicate and confirm the observed associations.

Mortality and neurological outcomes in extremely and very preterm infants born to mothers with hypertensive disorders of pregnancy

To evaluate the impact of maternal hypertensive disorders of pregnancy (HDP) on mortality and neurological outcomes in extremely and very preterm infants using a nationwide neonatal database in Japan. This population-based retrospective study was based on an analysis of data collected by the Neonatal Research Network of Japan from 2003 to 2015 of neonates weighing 1,500 g or less at birth, between 22 and 31 weeks’ gestation. A total of 21,659 infants were randomly divided into two groups, HDP (n = 4,584) and non-HDP (n = 4,584), at a ratio of 1:1 after stratification by four factors including maternal age, parity, weeks of gestation, and year of delivery. Short-term (neonatal period) and medium-term (3 years of age) mortality and neurological outcomes were compared between the two groups by logistic regression analyses. In univariate analysis, HDP was associated with an increased risk for in-hospital death (crude odds ratio [OR], 1.31; 95% confidence interval, 1.04–1.63) and a decreased risk for severe intraventricular haemorrhage (0.68; 0.53–0.87) and periventricular leukomalacia (0.60; 0.48–0.77). In multivariate analysis, HDP was significantly associated with a lower risk for in-hospital death (adjusted OR, 0.61; 0.47–0.80), severe intraventricular haemorrhage (0.47; 0.35–0.63), periventricular leukomalacia (0.59; 0.45–0.78), neonatal seizures (0.40; 0.28–0.57) and cerebral palsy (0.70; 0.52–0.95) at 3 years after adjustment for covariates including birth weight. These results were consistent with those of additional analyses, which excluded cases with histological chorioamnionitis and which divided the infants into two subgroups (22–27 gestational weeks and 28–31 gestational weeks). Maternal HDP was associated with an increased risk for in-hospital death without adjusting for covariates, but it was also associated with a lower risk for mortality and adverse neurological outcomes in extremely and very preterm infants if all covariates except HDP were identical.

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.

Single-nucleotide polymorphism screening and RNA sequencing of key messenger RNAs associated with neonatal hypoxic-ischemia brain damage

A single-nucleotide polymorphism (SNP) is an alteration in one nucleotide in a certain position within a genome. SNPs are associated with disease susceptibility. However, the influences of SNPs on the pathogenesis of neonatal hypoxic-ischemic brain damage remain elusive. Seven-day-old rats were used to establish a hypoxic ischemic encephalopathy model. SNPs and expression profiles of mRNAs were analyzed in hypoxic ischemic encephalopathy model rats using RNA sequencing. Genes exhibiting SNPs associated with hypoxic ischemic encephalopathy were identified and studied by gene ontology and pathway analysis to identify their possible involvement in the disease mechanism. We identified 89 up-regulated genes containing SNPs that were mainly located on chromosome 1 and 2. Gene ontology analysis indicated that the up-regulated genes containing SNPs are mainly involved in angiogenesis, wound healing and glutamatergic synapse and biological processing of calcium-activated chloride channels. Signaling pathway analysis indicated that the differentially expressed genes play a role in glutamatergic synapses, long-term depression and oxytocin signaling. Moreover, intersection analysis of high throughput screening following PubMed retrieval and RNA sequencing for SNPs showed that CSRNP1, DUSP5 and LRRC25 were most relevant to hypoxic ischemic encephalopathy. Significant up-regulation of genes was confirmed by quantitative real-time polymerase chain reaction analysis of oxygen-glucose-deprived human fetal cortical neurons. Our results indicate that CSRNP1, DUSP5 and LRRC25, containing SNPs, may be involved in the pathogenesis of hypoxic ischemic encephalopathy. These findings indicate a novel direction for further hypoxic ischemic encephalopathy research. This animal study was approved on February 5, 2017 by the Animal Care and Use Committee of Kunming Medical University, Yunnan Province, China (approval No. kmmu2019038). Cerebral tissue collection from a human fetus was approved on September 30, 2015 by the Ethics Committee of Kunming Medical University, China (approval No. 2015-9).

A single-nucleotide polymorphism induced alternative splicing in Tacr3 involves in hypoxic-ischemic brain damage

Single-nucleotide polymorphism (SNP) and Alternative splicing (AS) were found to be implicated in certain diseases, nevertheless, the contributions of mRNA SNPs and AS to pathogenesis in developing rat brains with hypoxic-ischemic encephalopathy (HIE) remained largely vague. Additionally, the disease associated with Tacr3 was normosmic congenital hypogonadotropic hypogonadism, while the relationship between HIE and Tacr3 remained largely elusive. The current study was designed to investigate the differentially expressed mRNAs and related SNPs as well as AS in neonatal rats subjected to HIE to identify if the exhibition of AS was associated with SNPs under pathological condition. Firstly, we used postnatal day 7 Sprague-Dawley rats to construct neonatal HIE model, and analyzed the expression profiles of SNP mRNA in hypoxic-ischemic (HI) and sham brains by using RNA sequencing. Then four genes, including Mdfic, Lpp, Bag3 and Tacr3, connecting with HIE and exhibiting SNPs and AS were identified by bioinformatics analysis. Moreover, combined with exonic splicing enhancer (ESE) and alternative splice site predictor (ASSP) analysis, we found that Tacr3 is associated specifically with HIE through 258547789 G > A SNP in inside the Alt First Exon and 258548573 G > A SNP in outside the Alt First Exon. Taken together, our study provides new evidence to understand the role of Tacr3 in HIE and it is possibly a potential target for the treatment of HIE in future clinic trial.

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.

Early development of the human placenta and pregnancy complications

An adequately sized placenta at a suitable site with appropriate depth and centripetal progression of implantation are the major factors for optimal fetal development. The cytotrophoblasts surround the blastocyst fuses at the site of the uterine attachment. This forms a second layer of multinucleated syncytiotrophoblasts that constitutes the inner epithelial boundary of the chorionic villous against the intervillous space. In a normal pregnancy, extravillous cytotrophoblasts (EVT) invade and obstruct the spiral arteries and remodel them. Vacuoles in the syncytial cell layer fuse and develop the intervillous space. The inner cell mass (embryoblast) gives rise to the umbilical cord and the mesenchyme in the chorionic villi. Vasculogenesis starts with the formation of hemangioblastic cords in this mesenchyme. The trophoblastic cell columns anchor the placenta. A variety of molecular pathways participate in the placentation process. Placental morphogenesis occurs mainly through complex cellular interactions between the chorionic villous and the extravillous cytotrophoblasts. The formation of the normal structure of the chorionic villi, syncytiotrophoblast layer and vasculature is essential for placental function, hormone production, and regulation of fetal growth. At each stage of placental development, genetic variants, exposure to infection, poor vascular function, oxidative stress, or failure of normal development can all lead to abnormal formation resulting in the clinical complications of pregnancy such as fetal growth disorders, neonatal neurologic abnormalities, placental adhesions, and inflammatory problems as well as maternal disease such as preeclampsia.

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.

Association of NOS1 gene polymorphisms with cerebral palsy in a Han Chinese population: a case-control study

Background

Cerebral palsy (CP) is the leading cause of motor disability in children; however, its pathogenesis is unknown in most cases. Growing evidence suggests that Nitric oxide synthase 1 (NOS1) is involved in neural development and neurologic diseases. The purpose of this study was to determine whether genetic variants of NOS1 contribute to CP susceptibility in a Han Chinese population.

Methods

A case-control study involving 652 CP patients and 636 healthy controls was conducted. Six SNPs in the NOS1 gene (rs3782219, rs6490121, rs2293054, rs10774909, rs3741475, and rs2682826) were selected, and the MassARRAY typing technique was applied for genotyping. Data analysis was conducted using SHEsis online software, and multiple test corrections were performed using SNPSpD online software.

Results

There were no significant differences in genotype and allele frequencies between patients and controls for the SNPs except rs6490121, which deviated from Hardy-Weinberg equilibrium and was excluded from further analyses. Subgroup analysis revealed differences in genotype frequencies between the CP with neonatal encephalopathy group (CP + NE) and control group for rs10774909, rs3741475, and rs2682826 (after SNPSpD correction, p = 0.004, 0.012, and 0.002, respectively). The T allele of NOS1 SNP rs3782219 was negatively associated with spastic quadriplegia (OR = 0.742, 95% CI = 0.600–0.918, after SNPSpD correction, p = 0.023). There were no differences in allele or genotype frequencies between CP subgroups and controls for the other genetic polymorphisms.

Conclusions

NOS1 is associated with CP + NE and spastic quadriplegia, suggesting that NOS1 is likely involved in the pathogenesis of CP and that it is a potential therapeutic target for treatment of cerebral injury.

Electronic supplementary material

The online version of this article (10.1186/s12920-018-0374-6) contains supplementary material, which is available to authorized users.

Integrative Review of Genetic Factors Influencing Neurodevelopmental Outcomes in Preterm Infants

Preterm infants are at elevated risk for a host of neurodevelopmental problems, including disorders that appear later in life. Gene-environment interactions and prematurity may combine to increase the risk for poor neurodevelopmental outcomes. Increasing evidence supports a genetic link to risk for atypical development; however, no genomic risk profiles are currently used for infants without apparent genetic disorders. The purpose of this review was to synthesize recent evidence of genetic associations with atypical neurodevelopmental outcomes that may affect preterm infants who do not have a rare genetic disease. Electronic and hand-search strategies were used to find relevant articles that were English-language, peer-reviewed primary research or meta-analysis reports published between July 2009 and July 2014, involving human participants. Articles included in the analysis (N = 29) used a wide range of study designs and methodologies, complicating the analysis. An integrative-review design was used to synthesize the data. Numerous genes (n = 43) and additional large deletion copy number variants were associated with neurodevelopmental outcomes, including cognition, attention, perception, psychiatric disease, autism spectrum disorder, cerebral palsy, infant behavior, and alterations in brain architecture. The creation of genetic risk profiles for complex disorders of neurodevelopment is presently hindered by inconsistent genetic-association evidence, methodological considerations, reporting problems, and lack of replication. However, several avenues of investigation offer promise, including large (>100 kb) copy number variants and the candidate genes MET, NRG3, and SLC6A4, each of which were reported to have associations with neurodevelopmental outcomes in multiple, high-quality studies.

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.