Markers Of Autism Risk In Babies-Learning Early Signs Research Articles

Commonly used genomic arrays may lose information due to imperfect coverage of discovered variants for autism spectrum disorder

BackgroundCommon genetic variation has been shown to account for a large proportion of ASD heritability. Polygenic scores generated for autism spectrum disorder (ASD-PGS) using the most recent discovery data, however, explain less variance than expected, despite reporting significant associations with ASD and other ASD-related traits. Here, we investigate the extent to which information loss on the target study genome-wide microarray weakens the predictive power of the ASD-PGS.MethodsWe studied genotype data from three cohorts of individuals with high familial liability for ASD: The Early Autism Risk Longitudinal Investigation (EARLI), Markers of Autism Risk in Babies-Learning Early Signs (MARBLES), and the Infant Brain Imaging Study (IBIS), and one population-based sample, Study to Explore Early Development Phase I (SEED I). Individuals were genotyped on different microarrays ranging from 1 to 5 million sites. Coverage of the top 88 genome-wide suggestive variants implicated in the discovery was evaluated in all four studies before quality control (QC), after QC, and after imputation. We then created a novel method to assess coverage on the resulting ASD-PGS by correlating a PGS informed by a comprehensive list of variants to a PGS informed with only the available variants.ResultsPrior to imputations, None of the four cohorts directly or indirectly covered all 88 variants among the measured genotype data. After imputation, the two cohorts genotyped on 5-million arrays reached full coverage. Analysis of our novel metric showed generally high genome-wide coverage across all four studies, but a greater number of SNPs informing the ASD-PGS did not result in improved coverage according to our metric.Limitations.The studies we analyzed contained modest sample sizes. Our analyses included microarrays with more than 1-million sites, so smaller arrays such as Global Diversity and the PsychArray were not included. Our PGS metric for ASD is only generalizable to samples of European ancestries, though the coverage metric can be computed for traits that have sufficiently large-sized discovery findings in other ancestries.ConclusionsWe show that commonly used genotyping microarrays have incomplete coverage for common ASD variants, and imputation cannot always recover lost information. Our novel metric provides an intuitive approach to reporting information loss in PGS and an alternative to reporting the total number of SNPs included in the PGS. While applied only to ASD here, this metric can easily be used with other traits.

Exposure to heavy metals in utero and autism spectrum disorder at age 3: a meta-analysis of two longitudinal cohorts of siblings of children with autism

BackgroundAutism spectrum disorder (ASD) is a prevalent and heterogeneous neurodevelopmental disorder. Risk is attributed to genetic and prenatal environmental factors, though the environmental agents are incompletely characterized.MethodsIn Early Autism Risk Longitudinal Investigation (EARLI) and Markers of Autism Risk in Babies Learning Early Signs (MARBLES), two pregnancy cohorts of siblings of children with ASD, urinary metals concentrations during two pregnancy time periods (< 28 weeks and ≥ 28 weeks of gestation) were measured using inductively coupled plasma mass spectrometry. At age three, clinicians assessed ASD with DSM-5 criteria. In an exposure-wide association framework, using multivariable log binomial regression, we examined each metal for association with ASD status, adjusting for gestational age at urine sampling, child sex, age at pregnancy, race/ethnicity and education. We meta-analyzed across the two cohorts.ResultsIn EARLI (n = 170) 17% of children were diagnosed with ASD, and 44% were classified as having non-neurotypical development (Non-TD). In MARBLES (n = 231), 21% were diagnosed with ASD, and 14% classified as Non-TD. During the first and second trimester period (< 28 weeks), having cadmium concentration over the level of detection was associated with 1.69 (1.08, 2.64) times higher risk of ASD, and 1.29 (0.95, 1.75)times higher risk of Non-TD.A doubling of first and second trimester cesium concentration was marginally associated with 1.89 (0.94, 3.80) times higher risk of ASD, and a doubling of third trimester cesium with 1.69 (0.97, 2.95) times higher risk of ASD.ConclusionExposure in utero to elevated levels of cadmium and cesium, as measured in urine collected during pregnancy, was associated with increased risk of developing ASD.

Neurodevelopment and Metabolism in the Maternal-Placental-Fetal Unit.

Disturbances in maternal, placental, and fetal metabolism are associated with developmental outcomes. Associations of maternal, placental, and fetal metabolism with subsequent neurodevelopmental outcomes in the child are understudied. To investigate the metabolic associations within the maternal-placental-fetal unit and subsequent neurodevelopmental outcomes in younger siblings of children with autism spectrum disorder (ASD). This cohort study was conducted within a subset of the Markers of Autism Risk in Babies, Learning Early Signs (MARBLES) cohort. MARBLES is a prospective birth cohort of younger siblings of children with ASD assessed for neurodevelopmental outcomes at approximately age 36 months. Participants in MARBLES were recruited through the UC Davis MIND Institute. This subset of the MARBLES cohort included younger siblings born between 2009 and 2015. Maternal third trimester serum, placental tissue, and umbilical cord serum samples were collected from participants. Only pregnancies with at least 2 of these sample types were included in this analysis. Data analysis was conducted from March 1, 2023, to March 15, 2024. Quantitative metabolomics analysis was conducted on maternal third trimester serum, as well as placental tissue and umbilical cord serum collected at delivery. Using the Autism Diagnostic Observation Schedule and Mullen Scales of Early Learning, outcomes were classified as ASD, other nontypical development (non-TD), and typical development (TD). This analysis included 100 maternal serum samples, 141 placental samples, and 124 umbilical cord serum samples from 152 pregnancies (median [IQR] maternal age, 34.6 [30.8-38.3] years; median [IQR] gestational age, 39.0 [38.6-39.7] weeks; 87 [57.2%] male infants). There was no evidence that the maternal third trimester serum metabolome was significantly associated with the other metabolomes. The placental and cord serum metabolomes were highly correlated (first latent variate pair: R2 = 0.75; P < .001) and the variate scores for each tissue were significantly associated with reduced risk of non-TD (placenta: relative risk [RR], 0.13; 95% CI, 0.02-0.71; cord: RR, 0.13; 95% CI, 0.03-0.70) but not ASD (placenta: RR, 1.09; 95% CI, 0.42-2.81; cord: RR, 0.63; 95% CI, 0.23-1.73) compared with the TD reference group. In this cohort study of children with high familial risk of ASD, placental and cord serum metabolism at delivery were highly correlated. Furthermore, placental and cord serum metabolic profiles were associated with risk of non-TD.

Association of Breastfeeding Duration with Neurodevelopmental Outcomes in an Enriched Familial Likelihood Cohort for Autism Spectrum Disorder.

This study aimed to compare the breastfeeding (BF) duration of the younger siblings of children with ASD in an enriched-likelihood cohort for autism spectrum disorder (ASD), and to determine whether longer BF duration was associated with differences in neurodevelopmental outcomes in this cohort. Information on BF practices was collected via surveys in the MARBLES (Markers of Autism Risk in Babies-Learning Early Signs) study. Developmental evaluations, including the Mullen Scales of Early Learning and the Autism Diagnostic Observation Schedule, were conducted by expert clinicians. Participants' neurodevelopmental outcome was classified by an algorithm into three groups: typical development, ASD, and non-typical development. The median duration of BF was 10.70months (interquartile range of 12.07months). There were no significant differences in the distribution of duration of BF among the three neurodevelopmental outcome categories. Children in this enriched-likelihood cohort who were breastfed for > 12months had significantly higher scores on cognitive testing compared to those who were breastfed for 0-3months. There was no significant difference in ASD symptomatology or ASD risk based on BF duration.

Prenatal perceived stress and urinary cortisol as risk factors for ASD and non-typical developmental outcomes in the MARBLES study

BackgroundFindings for prenatal stress, previously measured through stressful life event surveys items or biomarkers, in association with ASD are inconsistent. We prospectively examined prenatal perceived stress and prenatal urinary cortisol (PUC) in association with ASD and other non-typical developmental (Non-TD) outcomes in the child in a high familial likelihood cohort. MethodsThe Perceived Stress Scale questionnaire was used to measure perceived stress in the longitudinal Markers of Autism Risk in Babies: Learning Early Signs (MARBLES) Study. Cortisol was measured through 24-hr urine collections. At three years of age, an algorithm consisting of scores from the Autism Diagnostic Observation Schedule (ADOS) and Mullen Scales of Early Learning (MSEL) was used to classify children with ASD, Non-TD, or typically developing (TD) outcomes. Relative risk ratios (RRR) with TD as the reference were estimated using multinomial logistic regression. ResultsIncreased perceived stress was associated with Non-TD in trimester 1 (RRR 1.10; 95% CI: 1.00, 1.21) and ASD in trimesters 2 and 3 (RRR 1.08; 95% CI: 1.02, 1.14 and RRR 1.08; 95% CI: 1.03, 1.14, respectively). Results with PUC were non-significant but were in the direction consistent with previous findings suggesting that decreased cortisol levels are associated with higher likelihood of ASD. ConclusionsFindings support the hypothesis that higher perceived stress is associated with increased likelihood of ASD and possibly Non-TD, relative to TD. This suggests that stress reduction interventions during pregnancy could serve as preventative measures that help optimize the child’s long-term health. Larger studies are needed to replicate these findings.

Maternal preconception and prenatal stressful life events in association with child neurodevelopmental outcome in MARBLES: A high familial likelihood cohort

BackgroundPrenatal stressful life events (SLEs) have been inconsistently associated with autism spectrum disorder (ASD). Mothers who are already raising a child with ASD could experience compounding effects of prenatal SLEs. This study prospectively examined prenatal SLEs in association with child neurodevelopmental outcomes in a high familial likelihood cohort. MethodsParticipants were 317 mother-child pairs from the Markers of Autism Risk in Babies: Learning Early Signs (MARBLES) Study, where pregnant women have previously had at least one other child with ASD. Mothers were interviewed during and at the end of pregnancy about whether they had experienced any of 7 SLE categories relating to finance, marriage, death, and more.Child neurodevelopment at three years old was classified as typically developing (TD), Non-TD, or ASD using an algorithm applied to Autism Diagnostic Observation Schedule (ADOS) and the Mullen Scales of Early Learning (MSEL) scores. Relative risk ratios (RRR) with TD as the reference outcome were estimated using multinomial logistic regression. ResultsExperiencing legal problems was significantly associated with an increased relative risk of child Non-TD (RRR 3.75; 95% CI: 1.15, 12.22). However, this finding was based on a small sample size (n = 6) and should be interpreted with caution. All other associations with Non-TD and ASD were non-significant. ConclusionsFindings agree with previous literature suggesting prenatal SLEs might not increase likelihood for ASD and most were not associated with Non-TD. Future studies measuring perceived stress or stress biomarkers are warranted to further understand the true association of prenatal stress and likelihood of ASD.

Prenatal exposure to per- and polyfluoroalkyl substances and child behavioral problems

BackgroundPrenatal exposure to per- and polyfluoroalkyl substances (PFAS) may adversely affect child behaviors; however, findings of epidemiologic studies are inconsistent. We examined prenatal PFAS exposure in association with child behavioral problems. MethodsParticipants were 177 mother–child pairs from MARBLES (Markers of Autism Risk in Babies – Learning Early Signs), a cohort with elevated familial likelihood of autism spectrum disorder (ASD). We quantified nine PFAS in maternal serum (1–3 samples per mother) collected from the 1st to 3rd trimesters of pregnancy. Child behavioral problems were assessed at 3 years of age using the Child Behavior Checklist (CBCL), developed to test for various behavioral problems of children. We examined associations of the CBCL scores with individual PFAS concentrations and with their mixture using negative binomial regression and weighted quantile sum regression models. ResultsHigher prenatal perfluorononanoate (PFNA) concentrations were associated with higher scores of externalizing problems [β = 0.16, 95% CI (0.01, 0.32)] and aggressive behavior [β = 0.17 (0.01, 0.32)]. Higher PFNA, perfluorooctane sulfonate (PFOS), and perfluorodecanoate (PFDA) were associated with higher scores of sleep problems [β = 0.34 (0.15, 0.54) for PFNA, β = 0.20 (0.02, 0.37) for PFOS, and β = 0.19 (0.00, 0.37) for PFDA]. No significant associations observed for typically developing children, whereas PFOS, PFNA, and PFDA were associated with several behavioral problems among children diagnosed with ASD or other neurodevelopmental concerns. Exposure to a mixture of PFAS was associated with higher scores of sleep problems and aggressive behavior, mostly contributed by PFNA and PFDA. ConclusionsOur study showed that prenatal exposure to some PFAS could increase child behavioral problems at 3 years of age. However, our results should be interpreted with caution because we relied on data from a cohort with increased familial likelihood of ASD and thereby had more behavioral problems.

Prenatal Metal Exposures and Child Social Responsiveness Scale Scores in 2 Prospective Studies.

Prenatal exposure to metals is hypothesized to be associated with child autism. We aim to investigate the joint and individual effects of prenatal exposure to urine metals including lead (Pb), mercury (Hg), manganese (Mn), and selenium (Se) on child Social Responsiveness Scale (SRS) scores. We used data from 2 cohorts enriched for likelihood of autism spectrum disorder (ASD): Early Autism Risk Longitudinal Investigation (EARLI) and the Markers of Autism Risk in Babies-Learning Early Signs (MARBLES) studies. Metal concentrations were measured in urine collected during pregnancy. We used Bayesian Kernel Machine Regression and linear regression models to investigate both joint and independent associations of metals with SRS Z-scores in each cohort. We adjusted for maternal age at delivery, interpregnancy interval, maternal education, child race/ethnicity, child sex, and/or study site. The final analytic sample consisted of 251 mother-child pairs. When Pb, Hg, Se, and Mn were at their 75th percentiles, there was a 0.03 increase (95% credible interval [CI]: -0.11, 0.17) in EARLI and 0.07 decrease (95% CI: -0.29, 0.15) in MARBLES in childhood SRS Z-scores, compared to when all 4 metals were at their 50th percentiles. In both cohorts, increasing concentrations of Pb were associated with increasing values of SRS Z-scores, fixing the other metals to their 50th percentiles. However, all the 95% credible intervals contained the null. There were no clear monotonic associations between the overall prenatal metal mixture in pregnancy and childhood SRS Z-scores at 36 months. There were also no clear associations between individual metals within this mixture and childhood SRS Z-scores at 36 months. The overall effects of the metal mixture and the individual effects of each metal within this mixture on offspring SRS Z-scores might be heterogeneous across child sex and cohort. Further studies with larger sample sizes are warranted.

Fine particulate matter shown to influence cytokine and chemokine levels during pregnancy

Background and Aim: Pregnancy is a period vulnerable to environmental exposures like air pollution that disrupt immune regulation or induce inflammatory responses. Methods: Participants were 148 mother–child pairs from MARBLES (Markers of Autism Risk in Babies – Learning Early Signs), a high familial risk ASD cohort. Self-reported maternal address history was obtained for the entire pregnancy period and the 3 months prior to pregnancy. Daily PM2.5 (particulate matter &amp;#x3c; 2.5 µm in diameter) exposure values were spatially interpolated from the U.S. Environmental Protection Agency’s (EPA) Air Quality System (AQS) monitoring stations’ locations to the residence locations using inverse distance-squared weighting. Trimester-specific PM2.5 averages were assigned. Maternal plasma samples from each trimester were quantified for 29 cytokines and chemokines using Luminex multiplex analysis technology. Cytokines and chemokines were natural log transformed and standardized. Betas and 95% confidence intervals (CIs) for an interquartile range (IQR) change in PM2.5 were estimated using confounder-adjusted linear regression. Results: Pre-pregnancy PM2.5 was associated with a statistically significant increase in first trimester IL-8, IL-1

Maternal Serum and Placental Metabolomes in Association with Prenatal Phthalate Exposure and Neurodevelopmental Outcomes in the MARBLES Cohort.

Prenatal exposure to phthalates, a family of endocrine-disrupting plasticizers, is associated with disruption of maternal metabolism and impaired neurodevelopment. We investigated associations between prenatal phthalate exposure and alterations of both the maternal third trimester serum metabolome and the placental metabolome at birth, and associations of these with child neurodevelopmental outcomes using data and samples from the Markers of Autism Risk in Babies Learning Early Signs (MARBLES) cohort. The third trimester serum (n = 106) and placental (n = 132) metabolomes were investigated using 1H nuclear magnetic resonance spectroscopy. Children were assessed clinically for autism spectrum disorder (ASD) and cognitive development. Although none of the urinary phthalate metabolite concentrations were associated with maternal serum metabolites after adjustment for covariates, mixture analysis using quantile g-computation revealed alterations in placental metabolites with increasing concentrations of phthalate metabolites that included reduced concentrations of 2-hydoxybutyrate, carnitine, O-acetylcarnitine, glucitol, and N-acetylneuraminate. Child neurodevelopmental outcome was not associated with the third trimester serum metabolome, but it was correlated with the placental metabolome in male children only. Maternal phthalate exposure during pregnancy is associated with differences in the placental metabolome at delivery, and the placental metabolome is associated with neurodevelopmental outcomes in males in a cohort with high familial ASD risk.

Prenatal Exposure to Ambient Air Pollution and Epigenetic Aging at Birth in Newborns.

In utero air pollution exposure has been associated with adverse birth outcomes, yet effects of air pollutants on regulatory mechanisms in fetal growth and critical windows of vulnerability during pregnancy are not well understood. There is evidence that epigenetic alterations may contribute to these effects. DNA methylation (DNAm) based age estimators have been developed and studied extensively with health outcomes in recent years. Growing literature suggests environmental factors, such as air pollution and smoking, can influence epigenetic aging. However, little is known about the effect of prenatal air pollution exposure on epigenetic aging. In this study, we leveraged existing data on prenatal air pollution exposure and cord blood DNAm from 332 mother-child pairs in the Early Autism Risk Longitudinal Investigation (EARLI) and Markers of Autism Risk in Babies-Learning Early Signs (MARBLES), two pregnancy cohorts enrolling women who had a previous child diagnosed with autism spectrum disorder, to assess the relationship of prenatal exposure to air pollution and epigenetic aging at birth. DNAm age was computed using existing epigenetic clock algorithms for cord blood tissue—Knight and Bohlin. Epigenetic age acceleration was defined as the residual of regressing chronological gestational age on DNAm age, accounting for cell type proportions. Multivariable linear regression models and distributed lag models (DLMs), adjusting for child sex, maternal race/ethnicity, study sites, year of birth, maternal education, were completed. In the single-pollutant analysis, we observed exposure to PM2.5, PM10, and O3 during preconception period and pregnancy period were associated with decelerated epigenetic aging at birth. For example, pregnancy average PM10 exposure (per 10 unit increase) was associated with epigenetic age deceleration at birth (weeks) for both Knight and Bohlin clocks (β = −0.62, 95% CI: −1.17, −0.06; β = −0.32, 95% CI: −0.63, −0.01, respectively). Weekly DLMs revealed that increasing PM2.5 during the first trimester and second trimester were associated with decelerated epigenetic aging and that increasing PM10 during the preconception period was associated with decelerated epigenetic aging, using the Bohlin clock estimate. Prenatal ambient air pollution exposure, particularly in early and mid-pregnancy, was associated with decelerated epigenetic aging at birth.

Maternal Plasma Metabolic Profile Demarcates a Role for Neuroinflammation in Non-Typical Development of Children.

Maternal and cord plasma metabolomics were used to elucidate biological pathways associated with increased diagnosis risk for autism spectrum disorders (ASD). Metabolome-wide associations were assessed in both maternal and umbilical cord plasma in relation to diagnoses of ASD and other non-typical development (Non-TD) compared to typical development (TD) in the Markers of Autism risk in Babies: Learning Early Signs (MARBLES) cohort study of children born to mothers who already have at least one child with ASD. Analyses were stratified by sample matrix type, machine mode, and annotation confidence level. Dimensionality reduction techniques were used [i.e, principal component analysis (PCA) and random subset weighted quantile sum regression (WQSRS)] to minimize the high multiple comparison burden. With WQSRS, a metabolite mixture obtained from the negative mode of maternal plasma decreased the odds of Non-TD compared to TD. These metabolites, all related to the prostaglandin pathway, underscored the relevance of neuroinflammation status. No other significant findings were observed. Dimensionality reduction strategies provided confirming evidence that a set of maternal plasma metabolites are important in distinguishing Non-TD compared to TD diagnosis. A lower risk for Non-TD was linked to anti-inflammatory elements, thereby linking neuroinflammation to detrimental brain function consistent with studies ranging from neurodevelopment to neurodegeneration.

Prenatal exposure to per- and polyfluoroalkyl substances and cognitive development in infancy and toddlerhood

Background/ObjectivePer- and polyfluoroalkyl substances (PFAS) have neurobehavioral toxicity in experimental studies. Evidence on associations between prenatal PFAS exposure and child's cognitive development is inconsistent partly due to differences in assessment time points and tools. We examined associations of prenatal maternal serum PFAS concentrations with child's cognitive development assessed at multiple time points in infancy and toddlerhood. MethodsWe included 140 mother-child pairs from MARBLES (Markers of Autism Risk in Babies – Learning Early Signs), a longitudinal cohort of children with a first degree relative who was diagnosed with autism spectrum disorder followed from birth. Study children's cognitive development was assessed at 6, 12, 24, and 36 months of age using the Mullen Scales of Early Learning (MSEL) which provides an overall Early Learning Composite (normative mean of 100 and SD of 15) and four subscales (i.e., fine motor, visual reception, receptive language, and expressive language abilities; normative mean of 50 and SD of 10). Nine PFAS were quantified in maternal serum collected during pregnancy. We examined associations of log 2-transformed prenatal maternal serum PFAS concentrations with the MSEL Composite and each of the subscale scores at each time point as well as longitudinal changes in the scores over the four time points. We also classified trajectories into low- and high-score groups and fit Poisson regression models to estimate associations expressed as relative risks (RR). ResultsAmong six PFAS detected in more than 60% of the samples, prenatal maternal serum perfluorooctanoate (PFOA) was inversely associated with child's Composite score at 24 months (β = −5.22, 95% CI: −8.27, −2.17) and 36 months of age (β = −5.18, 95% CI: −9.46, −0.91), while other five PFAS were not strongly associated with Composite score at any time points. When assessing longitudinal changes in the scores over the four time points, PFOA was associated with trajectories having a negative slope for Composite scores and all four subscales. When examining trajectories of the scores between low- and high-score groups, PFOA was associated with having lower and/or decreasing Composite scores (RR = 1.49, 95% CI: 1.09, 2.03). ConclusionsPrenatal PFOA appears to adversely affect child's cognitive development in toddlerhood in this study population. Because a large fraction of MARBLES children is at risk for atypical development, population-based studies are needed to confirm our findings.

Prenatal exposure to per- and polyfluoroalkyl substances in association with autism spectrum disorder in the MARBLES study

BackgroundPrenatal exposure to per- and polyfluoroalkyl substances (PFAS) has shown potential to adversely affect child brain development, but epidemiologic evidence remains inconsistent. We examined whether prenatal exposure to PFAS was associated with increased risk of autism spectrum disorder (ASD). MethodsParticipants were 173 mother–child pairs from MARBLES (Markers of Autism Risk in Babies – Learning Early Signs), a high-risk ASD cohort. At 3 years old, children were clinically confirmed for ASD and classified into ASD (n = 57) and typical development (TD, n = 116). We quantified nine PFAS in maternal serum collected during pregnancy. We examined associations of ASD with individual PFAS as well as the combined effect of PFAS on ASD using scores of the first principal component (PC-1) accounting for the largest variance. ResultsPrenatal perfluorooctanoate (PFOA) and perfluorononanoate (PFNA) showed positive associations (per 2-fold relative increase in concentration: relative risk (RR) = 1.20, 95% CI: 0.90, 1.61 [PFOA]; RR = 1.24, 95% CI: 0.91, 1.69 [PFNA]), while perfluorohexane sulfonate (PFHxS) showed a negative association (RR = 0.88, 95% CI: 0.77, 1.01) with ASD risk. When examining associations of ASD with untransformed PFAS concentrations, PFOA, PFNA, and PC-1 were associated with increased ASD risk (per nanogram per milliliter increase: RR = 1.31, 95% CI: 1.04, 1.65; RR = 1.79, 95% CI: 1.13, 2.85; RR = 1.10, 95% CI: 0.97, 1.25, respectively), while the RR of PFHxS moved toward the null. ConclusionsFrom this high-risk ASD cohort, we observed increased risk of ASD in children exposed to PFOA and PFNA. Further studies should be conducted in the general population because this population may have a larger fraction of cases resulting from genetic sources.

In utero pyrethroid pesticide exposure in relation to autism spectrum disorder (ASD) and other neurodevelopmental outcomes at 3 years in the MARBLES longitudinal cohort

BackgroundWe assessed the relationships between prenatal pyrethroid pesticide exposure and autism spectrum disorders (ASD) or non-typical development (non-TD) at 3 years. MethodsParticipants were mother-child pairs (n = 201) in the MARBLES (Markers of Autism Risk in Babies-Learning Early Signs) cohort. Because familial recurrence risk is high, MARBLES enrolls pregnant women with a family history of ASD. Children from these pregnancies were clinically assessed at 3 years of age and classified into 3 outcome categories: ASD, typically developing (TD), or non-TD (neither TD or ASD). Repeated maternal second and third trimester urine samples were analyzed for pyrethroid metabolite 3-phenoxybenzoic acid (3-PBA). Multinomial logistic regression was used to obtain relative risk ratios (RRR) linking 3-PBA concentrations averaged across each trimester and over pregnancy with child's outcome: ASD or non-TD vs. TD. Models were adjusted for specific gravity, maternal pre-pregnancy BMI, prenatal vitamin use, birth year, home-ownership, and pregnancy concentrations of TCPy (3,5,6-trichloro-2-pyridinol, a metabolite of chlorpyrifos). ResultsThe median specific gravity corrected 3-PBA concentration of all samples was 1.46 ng/mL. Greater second trimester 3-PBA concentrations were associated with a relative risk ratio (RRR) for ASD of (RRR: 1.50 (95% CI 0.89 to 2.51), p = 0.12). There were no differences between non-TD and TD. ConclusionsThis study found no evidence for differences in 3-PBA comparing non-TD with TD. A modestly elevated RRR was found comparing second trimester urinary 3-PBA concentrations for ASD versus TD; however, the confidence interval was wide and hence, these findings cannot be considered definitive.

Prenatal exposure to per- and polyfluoroalkyl substances and cognitive development in infancy and early childhood

Background/Aim: Pregnant women are exposed to per- and polyfluoroalkyl substances (PFAS), suspected neurodevelopmental toxicants. A growing number of epidemiological studies have investigated associations between prenatal PFAS exposure and child’s neurodevelopment, but the results varied by assessment time points and tools. We investigated associations between prenatal exposure to PFAS and child’s cognitive development at multiple assessment time points.Methods: We included 215 mother-child pairs from the MARBLES (Markers of Autism Risk in Babies - Learning Early Signs) longitudinal cohort study. Child’s cognitive functions were assessed using Mullen Scales of Early Learning (MSEL) at 6, 12, 24, and 36 months of age. Nine PFAS were quantified in maternal serum samples collected during pregnancy. We used multiple linear regression to estimate the change in MSEL scores in association with prenatal maternal PFAS concentrations at each assessment time point.Results: Higher prenatal maternal serum perfluorooctanoate (PFOA) was associated with lower MSEL Composite scores only at 24 months (β = -5.62, 95% CI: -10.6, -0.70). When compared to the lowest quartile, the third quartile of perfluorohexane sulfonate (PFHxS) was associated with increased Visual Reception scores at 6, 24, and 36 months. When stratified by child’s sex, females showed stronger associations of PFOA (β = -7.84, 95% CI: -15.1, -0.61) and PFHxS (β = -7.91, 95% CI: -15.2, -0.62) with decreased MSEL Composite scores at 36 months, compared to males.Conclusions: Our results suggest that prenatal PFOA may adversely affect child’s cognitive development at 24 months of age. Further studies using the same assessment tool with larger sample sizes are needed to confirm our findings.Keywords: cognitive development, Mullen Scales of Early Learning, PFAS, prenatal exposureDisclaimer: The findings and conclusions in this abstract are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention.

Prenatal exposure to per- and polyfluoroalkyl substances in association with autism spectrum disorder in the MARBLES study

Background/Aim: Prenatal exposure to per- and polyfluoroalkyl substances (PFAS) may adversely affect child brain development, but epidemiologic evidence remains inconsistent. We examined whether prenatal PFAS exposure was associated with increased risk of autism spectrum disorder (ASD).Methods: Participants were 204 mother-child pairs from MARBLES (Markers of Autism Risk in Babies - Learning Early Signs), which followed younger siblings of children with ASD. Children were clinically classified into ASD (n = 57), non-typical development (Non-TD, n = 31), and typical development (TD, n = 116). We quantified nine PFAS in maternal sera prospectively collected throughout pregnancy. Of 312 samples, 67, 142, and 103 samples were collected from the first, second, and third trimesters, respectively. We used multinomial logistic regression to investigate associations of individual PFAS concentrations with the risk of ASD and Non-TD.Results: Overall, most associations of average prenatal maternal PFAS serum concentrations with the risk of ASD and Non-TD were statistically insignificant. When restricting analyses to each trimester, perfluorooctanoate (PFOA) was associated with increased risk of ASD in the third trimester (RRR = 3.58, 95% CI: 1.01, 12.6). When stratified by maternal age at delivery (&lt;35, ≥35 years), among mothers ≥35 years old at delivery, ASD risk was associated with prenatal PFOA (RRR = 8.84, 95% CI: 1.70, 46.1), perfluorononanoate (RRR = 7.03, 95% CI: 1.35, 11.7), and perfluorodecanoate (RRR = 3.37, 95% CI: 1.04, 10.9).Conclusions: We found evidence that prenatal exposure to some PFAS was associated with increased risk of ASD among children whose mothers were 35 years old or older at delivery. Further studies should be conducted in the general population to confirm our findings.Keywords: autism spectrum disorder, maternal serum, PFASDisclaimer: The findings and conclusions in this abstract are those of the authors and do not necessarily represent the views of the CDC.

Temporal Trends of Exposure to Phthalates and Phthalate Alternatives in California Pregnant Women during 2007–2013: Comparison with Other Populations

Phthalates with potential adverse health effects are being replaced by other phthalates or phthalate alternatives. Little is known about temporal trends of phthalate exposure in pregnant women in the United States. We quantified 16 metabolites of eight phthalates and di(isononyl) cyclohexane-1,2-dicarboxylate (DINCH) in 656 urine samples collected from 192 California pregnant women in 2007-2013 during their second and third trimesters of pregnancy who participated in the MARBLES (Markers of Autism Risk in Babies-Learning Early Signs) study. We used multiple regression to estimate least squares geometric means of phthalate biomarker concentrations and annual percent changes over the study period. Biomarker concentrations of diethyl phthalate (DEP) and three phthalates with known toxicity and adverse health effects (i.e., butyl benzyl phthalate [BBzP], dibutyl phthalate [DBP], di(2-ethylhexyl) phthalate [DEHP]) decreased, while those of di-isobutyl phthalate [DiBP], di-isononyl phthalate [DiNP], and di-n-octyl phthalate [DOP] increased in California pregnant women during our study period. To understand broad social forces that may influence temporal trends and geographic variations in phthalate exposure across countries, we compared our phthalate biomarker concentrations with those of other populations. We observed over a factor of 2 differences in exposure across countries for some phthalate biomarkers and between pregnant and nonpregnant women for DEP.

A meta-analysis of two high-risk prospective cohort studies reveals autism-specific transcriptional changes to chromatin, autoimmune, and environmental response genes in umbilical cord blood

BackgroundAutism spectrum disorder (ASD) is a neurodevelopmental disorder that affects more than 1% of children in the USA. ASD risk is thought to arise from both genetic and environmental factors, with the perinatal period as a critical window. Understanding early transcriptional changes in ASD would assist in clarifying disease pathogenesis and identifying biomarkers. However, little is known about umbilical cord blood gene expression profiles in babies later diagnosed with ASD compared to non-typically developing and non-ASD (Non-TD) or typically developing (TD) children.MethodsGenome-wide transcript levels were measured by Affymetrix Human Gene 2.0 array in RNA from cord blood samples from both the Markers of Autism Risk in Babies-Learning Early Signs (MARBLES) and the Early Autism Risk Longitudinal Investigation (EARLI) high-risk pregnancy cohorts that enroll younger siblings of a child previously diagnosed with ASD. Younger siblings were diagnosed based on assessments at 36 months, and 59 ASD, 92 Non-TD, and 120 TD subjects were included. Using both differential expression analysis and weighted gene correlation network analysis, gene expression between ASD and TD, and between Non-TD and TD, was compared within each study and via meta-analysis.ResultsWhile cord blood gene expression differences comparing either ASD or Non-TD to TD did not reach genome-wide significance, 172 genes were nominally differentially expressed between ASD and TD cord blood (log2(fold change) > 0.1, p < 0.01). These genes were significantly enriched for functions in xenobiotic metabolism, chromatin regulation, and systemic lupus erythematosus (FDR q < 0.05). In contrast, 66 genes were nominally differentially expressed between Non-TD and TD, including 8 genes that were also differentially expressed in ASD. Gene coexpression modules were significantly correlated with demographic factors and cell type proportions.LimitationsASD-associated gene expression differences identified in this study are subtle, as cord blood is not the main affected tissue, it is composed of many cell types, and ASD is a heterogeneous disorder.ConclusionsThis is the first study to identify gene expression differences in cord blood specific to ASD through a meta-analysis across two prospective pregnancy cohorts. The enriched gene pathways support involvement of environmental, immune, and epigenetic mechanisms in ASD etiology.

Placental DNA methylation levels at CYP2E1 and IRS2 are associated with child outcome in a prospective autism study.

DNA methylation acts at the interface of genetic and environmental factors relevant for autism spectrum disorder (ASD). Placenta, normally discarded at birth, is a potentially rich source of DNA methylation patterns predictive of ASD in the child. Here, we performed whole methylome analyses of placentas from a prospective study MARBLES (Markers of Autism Risk in Babies-Learning Early Signs) of high-risk pregnancies. A total of 400 differentially methylated regions (DMRs) discriminated placentas stored from children later diagnosed with ASD compared to typically developing controls. These ASD DMRs were significantly enriched at promoters, mapped to 596 genes functionally enriched in neuronal development, and overlapped genetic ASD risk. ASD DMRs at CYP2E1 and IRS2 reached genome-wide significance, replicated by pyrosequencing and correlated with expression differences in brain. Methylation at CYP2E1 associated with both ASD diagnosis and genotype within the DMR. In contrast, methylation at IRS2 was unaffected by within DMR genotype but modified by preconceptional maternal prenatal vitamin use. This study therefore identified two potentially useful early epigenetic markers for ASD in placenta.