Genetic architecture, epigenetic influence and environment exposure in the pathogenesis of Autism

Implications of prenatal exposure to hyperandrogen for hippocampal neurodevelopment and autism-like behavior in offspring

Autism spectrum disorder (ASD) is a highly heterogeneous neurodevelopmental disorder that significantly jeopardizes the physical and mental well-being of children. Autism spectrum disorder results from a combination of environmental and genetic factors. Hyperandrogenic exposure during pregnancy increases their risk of developing autism. Nevertheless, the prenatal exposure to androgens affects offspring neurodevelopment and the underlying mechanisms have not been fully elucidated. In the present study, administration of excessive dihydrotestosterone (DHT) to pregnant mice was found to impair neuronal development and dendritic spine formation in offspring, inducing autism-like behaviors. Furthermore, through mRNA transcriptome sequencing technology, the key molecule Nr4a2 was identified during this process of change. Overexpression of Nr4a2 and treatment with amodiaquine (AQ) significantly improved the abnormal phenotypes in offspring caused by prenatal exposure to androgens. Overall, Nr4a2 emerges as a crucial molecule involved in the impairment of offspring neurodevelopment due to prenatal androgen exposure, which provides a new perspective for the in-depth study of the influencing factors and underlying mechanisms.

Anti-apoptotic capacity of MALAT1 on hippocampal neurons correlates with CASP3 DNA methylation in a mouse model of autism

Prior evidence has suggested the alleviatory effect of metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) on neuroinflammation in neurodegenerative diseases. This study primarily investigates the underlying mechanism of how the long non-coding RNA MALAT1 affects neuronal apoptosis in the hippocampus of mice with autism spectrum disorder (ASD). The findings demonstrate that CASP3 is highly expressed while MALAT1 is downregulated in the hippocampal neurons of autistic mice. MALAT1 mainly localizes within the cell nucleus and recruits DNA methyltransferases (including DNMT1, DNMT3a, and DNMT3b) to the promoter region of CASP3, promoting its methylation and further inhibiting its expression. In vitro experiments reveal that reducing MALAT1 expression promotes the expression of CASP3 and Bax while suppressing Bcl-2 expression, thereby enhancing cellular apoptosis. Conversely, increasing MALAT1 expression yields the opposite effect. Consequently, these results further confirm the role of MALAT1 in suppressing neuronal apoptosis in the hippocampus of mice with ASD through the regulation of CASP3 promoter methylation. Thus, this research unveils the significant roles of MALAT1 and CASP3 in the pathogenesis of ASD, offering new possibilities for future therapeutic interventions.

miR-92a-2-5p Regulates the Proliferation and Differentiation of ASD-Derived Neural Progenitor Cells

Autism spectrum disorder (ASD) is a group of complex neurodevelopmental disorders with abnormal behavior. However, the pathogenesis of ASD remains to be clarified. It has been demonstrated that miRNAs are essential regulators of ASD. However, it is still unclear how miR-92a-2-5p acts on the developing brain and the cell types directly. In this study, we used neural progenitor cells (NPCs) derived from ASD-hiPSCs as well as from neurotypical controls to examine the effects of miR-92a-2-5p on ASD-NPCs proliferation and neuronal differentiation, and whether miR-92a-2-5p could interact with genetic risk factor, DLG3 for ASD. We observed that miR-92a-2-5p upregulated in ASD-NPCs results in decreased proliferation and neuronal differentiation. Inhibition of miR-92a-2-5p could promote proliferation and neuronal differentiation of ASD-NPCs. DLG3 was negatively regulated by miR-92a-2-5p in NPCs. Our results suggest that miR-92a-2-5p is a strong risk factor for ASD and potentially contributes to neuropsychiatric disorders.

Autism Spectrum Disorder and Prenatal or Early Life Exposure to Pesticides: A Short Review

Background: Autism spectrum disorder (ASD) diagnoses have rapidly increased globally. Both environmental and genetic factors appear to contribute to the development of ASD. Several studies have shown a potential association between prenatal or postnatal pesticide exposure and the risk of developing ASD. Methods: We reviewed the available literature concerning the relationship between early life exposure to pesticides used in agriculture, such as organochlorines, organophosphates and pyrethroids, and ASD onset in childhood. We searched on Medline and Scopus for cohort or case–control studies published in English from 1977 to 2020. Results: A total of seven articles were selected for the review. We found a remarkable association between the maternal exposure to pyrethroid, as well as the exposure to organophosphate during pregnancy or in the first years of childhood, and the risk of ASD onset. This association was found to be less evident with organochlorine pesticides. Pregnancy seems to be the time when pesticide exposure appears to have the greatest impact on the onset of ASD in children. Conclusions: Among the different environmental pollutants, pesticides should be considered as emerging risk factors for ASD. The potential association identified between the exposure to pesticides and ASD needs to be implemented and confirmed by further epidemiological studies based on individual assessment both in outdoor and indoor conditions, including multiple confounding factors, and using statistical models that take into account single and multiple pesticide residues.

Clinical Characterization of a 6-Year-Old Patient with Autism and Two Adjacent Duplications on 10q11.22q11.23. A Case Report

Autism is a neurodevelopmental disorder presenting in the first 3 years of life. Deficits occur in the core areas of social communication and interaction and restricted, repetitive patterns of behavior, interests or activities. The causes of autism are unknown, but clinical genetic studies show strong evidence in favor of the involvement of genetic factors in etiology. Molecular genetic studies report some associations with candidate genes, and candidate regions have emerged from several genome-wide linkage studies. Here, we report a clinical case of autism in a 6-year-old boy with double duplication on 10q11.22q11.23 with ASD (Autism Spectrum Disorder), intellectual disability, developmental delay, hypotonia, gross-motor skills deficit, overgrowth and mild dysmorphic features. In the literature, only five cases of ASD with 10q11.21q11.23 duplication are reported. This is the first extensive clinical description of an ASD subject with 10q11.22q11.23 duplication. Our findings suggest that 10q11.21q11.23 microduplication could represent a copy number variant that predisposes to autism.

Predicting LncRNA-Disease Association Based on Generative Adversarial Network

BACKGROUND

Increasing research reveals that long non-coding RNAs (lncRNAs) play an important role in various biological processes of human diseases. Nonetheless, only a handful of lncRNA-disease associations have been experimentally verified. The study of lncRNA-disease association prediction based on the computational model has provided a preliminary basis for biological experiments to a great degree so as to cut down the huge cost of wet lab experiments.

OBJECTIVE

This study aims to learn the real distribution of lncRNA-disease association from a limited number of known lncRNA-disease association data. This paper proposes a new lncRNA-disease association prediction model called LDA-GAN based on a generative adversarial network (GAN).

METHOD

Aiming at the problems of slow convergence rate, training instabilities, and unavailability of discrete data in traditional GAN, LDA-GAN utilizes the Gumbel-softmax technology to construct a differentiable process for simulating discrete sampling. Meanwhile, the generator and the discriminator of LDA-GAN are integrated to establish the overall optimization goal based on the pairwise loss function.

RESULTS

Experiments on standard datasets demonstrate that LDA-GAN achieves not only high stability and high efficiency in the process of confrontation learning but also gives full play to the semi-supervised learning advantage of generative adversarial learning framework for unlabeled data, which further improves the prediction accuracy of lncRNA-disease association. Besides, case studies show that LDA-GAN can accurately generate potential diseases for several lncRNAs.

Neuroprotective Effect of α-Mangostin in the Ameliorating Propionic Acid-Induced Experimental Model of Autism in Wistar Rats

Several studies have documented the role of hyper-activation of extracellular signal-regulated kinases (ERK) in Autism pathogenesis. Alpha-mangostin (AMG) is a phytoconstituents with anti-oxidants, anti-inflammatory, and ERK inhibition properties in many diseases. Our research aims to investigate the neuroprotective effect of AMG in the rat model of intracerebroventricular-propionic acid (ICV-PPA) induced autism with a confirmation of its effect on the ERK signaling. Autism was induced in Wistar rats (total 36 rats; 18 male/18 female) by multiple doses of PPA through ICV injection for 11 days. Actophotometer and beam walking tasks were used to evaluate animals' motor abilities, and the Morris water maze task was utilized to confirm the cognition and memory in animals. Long term administration of AMG 100 mg/kg and AMG 200mg/kg continued from day 12 to day 44 of the experiment. Before that, animals were sacrificed, brains isolated, morphological, gross pathological studies were performed, and neurochemical analysis was performed in the brain homogenates. Cellular and molecular markers, including ERK, myelin basic protein, apoptotic markers including caspase-3, Bax, Bcl-2, neuroinflammatory markers, neurotransmitters, and oxidative stress markers, have been tested throughout the brain. Thus, AMG reduces the overactivation of the ERK signaling and also restored autism-like behavioral and neurochemical alterations.

Early-Life Exposure to Environmental Air Pollution and Autism Spectrum Disorder: A Review of Available Evidence

The number of children diagnosed with Autism Spectrum Disorder (ASD) has rapidly increased globally. Genetic and environmental factors both contribute to the development of ASD. Several studies showed linkage between prenatal, early postnatal air pollution exposure and the risk of developing ASD. We reviewed the available literature concerning the relationship between early-life exposure to air pollutants and ASD onset in childhood. We searched on Medline and Scopus for cohort or case-control studies published in English from 1977 to 2020. A total of 20 articles were selected for the review. We found a strong association between maternal exposure to particulate matter (PM) during pregnancy or in the first years of the children’s life and the risk of the ASD. This association was found to be stronger with PM_2.5 and less evident with the other pollutants. Current evidence suggest that pregnancy is the period in which exposure to environmental pollutants seems to be most impactful concerning the onset of ASD in children. Air pollution should be considered among the emerging risk factors for ASD. Further epidemiological and toxicological studies should address molecular pathways involved in the development of ASD and determine specific cause–effect associations.

Exploring the Association of Autism Spectrum Disorders and Constipation through Analysis of the Gut Microbiome

Over the past two decades, research into the role of the gut microbiome in regulating the central nervous system has rapidly increased. Several neurodevelopmental diseases have been linked to the unbalance of gut microbiota, including autism. Children on the autism spectrum often suffer from gastrointestinal symptoms, including constipation, which is four times more prevalent than it is in children without autism spectrum disorders (ASD). Although studies in animals have shown the crucial role of the microbiota in key aspects of neurodevelopment, there is currently no consensus on how the alteration of microbial composition affects the pathogenesis of ASD, let alone how it exerts an impact on the following comorbidities. In our study, we were able to control the effects of constipation on gut dysbiosis and distinguish neuropathological-related and gastrointestinal-related bacteria in ASD patients separately. By analyzing published data, eight additional bacteria significantly altered in autistic individuals were identified in our study. All of them had a decreased relative abundance in ASD patients, except Lactobacillaceae and Peptostreptococcaceae. Eighteen and eleven bacteria were significantly correlated with ASD symptoms and constipation, respectively. Among those, six bacteria were overlapped between the groups. We have found another six bacteria highly associated with constipation status in ASD patients only. By conducting Welch’s t-test, we were able to demonstrate the critical roles of microbes in ASD core and gastrointestinal symptoms and raised the hypotheses of their confounding and mediating effects on the relationship between the two symptoms.

Gut Bacteria Shared by Children and Their Mothers Associate with Developmental Level and Social Deficits in Autism Spectrum Disorder

The gut microbiota of autism spectrum disorder (ASD) children differs from that of children without ASD. The maternal gut microbiota impacts offspring gut microbiota. However, the relationship between the development of ASD and gut bacteria shared between children and their mothers remains elusive. Our study recruited 76 children with ASD and 47 age- and gender-matched children with typical development (TD), as well as the mothers of both groups, and investigated their gut microbiota using amplicon sequence variants (ASVs). The gut microbiota of ASD children was altered compared with that of children with TD, while no significant alterations were found in their mothers. We established 30 gut bacterial coabundance groups (CAGs) and found the relative abundances of CAG15 and CAG16 significantly decreased in ASD children. CAG15 showed a positive correlation with developmental level. The proportion of ASD children who shared either one of the two Lachnospiraceae ASVs from CAG15 with their mothers was significantly lower than that of children with TD. Moreover, we found that CAG12, CAG13, and CAG18 negatively correlated with the severity of social deficits in ASD children. ASD children who shared any one of the four (two Ruminococcaceae, one Lachnospiraceae, and one Collinsella) ASVs in CAG13 and CAG18 with their mothers showed a lower level of social deficits than ASD children that did not share those with their mothers. These data demonstrate that these shared gut bacteria in ASD children are associated with their developmental level and social deficits. This work provides a new direction toward understanding the role of the gut microbiota in the pathogenesis and development of ASD. (This study has been registered in the Chinese Clinical Trial Registry under number ChiCTR-RPC-16008139.)IMPORTANCE Gut microbiota may contribute to the pathogenesis and development of autism spectrum disorder. The maternal gut microbiota influences offspring gut microbial structure and composition. However, the relationship between the clinical symptoms of autism spectrum disorder and the gut bacteria shared between children and their mothers is not yet known. In our study, the gut microbiota of children with autism spectrum disorder differed from that of children with typical development, but there were no differences in the gut microbiota of their mothers. More importantly, gut bacteria shared between children with autism spectrum disorder and their mothers were related to developmental disabilities and social deficits. Thus, our study suggests that these shared gut bacteria may play an important role in the development of autism spectrum disorder. This provides a new direction for future studies aiming to explore the role of the gut microbiota in autism spectrum disorder.

The Possible Role of the Microbiota-Gut-Brain-Axis in Autism Spectrum Disorder

New research points to a possible link between autism spectrum disorder (ASD) and the gut microbiota as many autistic children have co-occurring gastrointestinal problems. This review focuses on specific alterations of gut microbiota mostly observed in autistic patients. Particularly, the mechanisms through which such alterations may trigger the production of the bacterial metabolites, or leaky gut in autistic people are described. Various altered metabolite levels were observed in the blood and urine of autistic children, many of which were of bacterial origin such as short chain fatty acids (SCFAs), indoles and lipopolysaccharides (LPS). A less integrative gut-blood-barrier is abundant in autistic individuals. This explains the leakage of bacterial metabolites into the patients, triggering new body responses or an altered metabolism. Some other co-occurring symptoms such as mitochondrial dysfunction, oxidative stress in cells, altered tight junctions in the blood-brain barrier and structural changes in the cortex, hippocampus, amygdala and cerebellum were also detected. Moreover, this paper suggests that ASD is associated with an unbalanced gut microbiota (dysbiosis). Although the cause-effect relationship between ASD and gut microbiota is not yet well established, the consumption of specific probiotics may represent a side-effect free tool to re-establish gut homeostasis and promote gut health. The diagnostic and therapeutic value of bacterial-derived compounds as new possible biomarkers, associated with perturbation in the phenylalanine metabolism, as well as potential therapeutic strategies will be discussed.

Correlation of Gut Microbiome Between ASD Children and Mothers and Potential Biomarkers for Risk Assessment

Variation of maternal gut microbiota may increase the risk of autism spectrum disorders (ASDs) in offspring. Animal studies have indicated that maternal gut microbiota is related to neurodevelopmental abnormalities in mouse offspring, while it is unclear whether there is a correlation between gut microbiota of ASD children and their mothers. We examined the relationships between gut microbiome profiles of ASD children and those of their mothers, and evaluated the clinical discriminatory power of discovered bacterial biomarkers. Gut microbiome was profiled and evaluated by 16S ribosomal RNA gene sequencing in stool samples of 59 mother–child pairs of ASD children and 30 matched mother–child pairs of healthy children. Significant differences were observed in the gut microbiome composition between ASD and healthy children in our Chinese cohort. Several unique bacterial biomarkers, such as Alcaligenaceae and Acinetobacter, were identified. Mothers of ASD children had more Proteobacteria, Alphaproteobacteria, Moraxellaceae, and Acinetobacter than mothers of healthy children. There was a clear correlation between gut microbiome profiles of children and their mothers; however, children with ASD still had unique bacterial biomarkers, such as Alcaligenaceae, Enterobacteriaceae, and Clostridium. Candidate biomarkers discovered in this study had remarkable discriminatory power. The identified patterns of mother–child gut microbiome profiles may be important for assessing risks during the early stage and planning of personalized treatment and prevention of ASD via microbiota modulation.

From bedside to bench and back: Translating ASD models

Autism spectrum disorders (ASD) represent a heterogeneous group of disorders defined by deficits in social interaction/communication and restricted interests, behaviors, or activities. Models of ASD, developed based on clinical data and observations, are used in basic science, the "bench," to better understand the pathophysiology of ASD and provide therapeutic options for patients in the clinic, the "bedside." Translational medicine creates a bridge between the bench and bedside that allows for clinical and basic science discoveries to challenge one another to improve the opportunities to bring novel therapies to patients. From the clinical side, biomarker work is expanding our understanding of possible mechanisms of ASD through measures of behavior, genetics, imaging modalities, and serum markers. These biomarkers could help to subclassify patients with ASD in order to better target treatments to a more homogeneous groups of patients most likely to respond to a candidate therapy. In turn, basic science has been responding to developments in clinical evaluation by improving bench models to mechanistically and phenotypically recapitulate the ASD phenotypes observed in clinic. While genetic models are identifying novel therapeutics targets at the bench, the clinical efforts are making progress by defining better outcome measures that are most representative of meaningful patient responses. In this review, we discuss some of these challenges in translational research in ASD and strategies for the bench and bedside to bridge the gap to achieve better benefits to patients.

Autism-related behaviors in the cyclooxygenase-2-deficient mouse model

Prostaglandin E2 (PGE2) is an endogenous lipid molecule involved in normal brain development. Cyclooxygenase-2 (COX2) is the main regulator of PGE2 synthesis. Emerging clinical and molecular research provides compelling evidence that abnormal COX2/PGE2 signaling is associated with autism spectrum disorder (ASD). We previously found that COX2 knockout mice had dysregulated expression of many ASD genes belonging to important biological pathways for neurodevelopment. The present study is the first to show the connection between irregular COX2/PGE2 signaling and autism-related behaviors in male and female COX2-deficient knockin, (COX)-2^- , mice at young (4-6 weeks) or adult (8-11 weeks) ages. Autism-related behaviors were prominent in male (COX)-2^- mice for most behavioral tests. In the open field test, (COX)-2^- mice traveled more than controls and adult male (COX)-2^- mice spent less time in the center indicating elevated hyperactive and anxiety-linked behaviors. (COX)-2^- mice also buried more marbles, with males burying more than females, suggesting increased anxiety and repetitive behaviors. Young male (COX)-2^- mice fell more frequently in the inverted screen test revealing motor deficits. The three-chamber sociability test found that adult female (COX)-2^- mice spent less time in the novel mouse chamber indicative of social abnormalities. In addition, male (COX)-2^- mice showed altered expression of several autism-linked genes: Wnt2, Glo1, Grm5 and Mmp9. Overall, our findings offer new insight into the involvement of disrupted COX2/PGE2 signaling in ASD pathology with age-related differences and greater impact on males. We propose that (COX)-2^- mice might serve as a novel model system to study specific types of autism.

Autism-associated Dyrk1a truncation mutants impair neuronal dendritic and spine growth and interfere with postnatal cortical development

Autism is a prevailing neurodevelopmental disorder with a large genetic/genomic component. Recently, the dual-specificity tyrosine-(Y)-phosphorylation-regulated kinase 1 A (DYRK1A) gene was implicated as a risk factor for autism spectrum disorder (ASD). We identified five DYRK1A variants in ASD patients and found that the dose of DYRK1A protein has a crucial role in various aspects of postnatal neural development. Dyrk1a loss of function and gain of function led to defects in dendritic growth, dendritic spine development and radial migration during cortical development. Importantly, two autism-associated truncations, R205X and E239X, were shown to be Dyrk1a loss-of-function mutants. Studies of the truncated Dyrk1a mutants may provide new insights into the role of Dyrk1a in brain development, as well as the role of Dyrk1a loss of function in the pathophysiology of autism.

The dopamine transporter role in psychiatric phenotypes

The dopamine transporter (DAT) is one of the most relevant and investigated neurotransmitter transporters. DAT is a plasma membrane protein which plays a homeostatic role, controlling both extracellular and intracellular concentrations of dopamine (DA). Since unbalanced DA levels are known to be involved in numerous mental disorders, a wealth of investigations has provided valuable insights concerning DAT role into normal brain functioning and pathological processes. Briefly, this extensive but non-systematic review discusses what is recently known about the role of SLC6A3 gene which encodes the dopamine transporter in psychiatric phenotypes. DAT protein, SLC6A3 gene, animal models, neuropsychology, and neuroimaging investigations are also concisely discussed. To conclude, current challenges are reviewed in order to provide perspectives for future studies.

A critical review of developmental exposure to particulate matter, autism spectrum disorder, and attention deficit hyperactivity disorder

Autism spectrum disorder (ASD) and attention deficit (hyperactivity) disorder (ADD/ADHD) are key focuses of current health research due to their increasing prevalence. The objective of this systematic literature search and critical review was to evaluate whether the human epidemiologic data indicate a pattern of association between ASD or ADD/ADHD and developmental exposure to particulate matter (PM), with a focus on exposures encountered before the age of three. A MEDLINE and EMBASE search was conducted; following preliminary and full-text screening, 14 relevant articles were identified for review. Three of the 14 studies were prospective cohort studies evaluating exposure to PM₁₀; 11 studies had a case-control design. There was no consistent association between developmental PM exposure and ASD across the three of the cohort studies. Seven of the case-control studies examined the relationship between PM_2.5 and/or PM₁₀ and ASD; four examined the relationship between developmental diesel PM exposure and ASD. Overall, there was low external consistency in results among studies of PM_2.5/PM₁₀ and ASD, with some reporting high internal consistency without significant associations, others showing associations with high internal consistency for specific exposure windows only (e.g., third trimester), and still others showing high consistency for moderate to strong associations between PM and ASD. The majority of studies reporting significant results had low effect sizes in conjunction with small sample sizes. The four studies of diesel PM and ASD also had low external consistency of results. Only one study evaluated associations with ADD/ADHD, and it found no significant associations with PM₁₀. The inconsistent findings across studies of developmental exposure to PM and ASD may be attributed to differences in the study populations, exposure assessments, outcome assessments, or chance. Further research is needed to understand the underlying biological mechanisms that lead to ASD and ADD/ADHD and how PM might be involved in those mechanisms, if at all. High-quality epidemiologic studies are also needed to conclusively determine whether developmental PM exposure is a causal factor for ASD or ADD/ADHD, with focus on a well-developed exposure assessment.

Integrative genomic analyses for identification and prioritization of long non-coding RNAs associated with autism

Genetic studies have identified many risk loci for autism spectrum disorder (ASD) although causal factors in the majority of cases are still unknown. Currently, known ASD risk genes are all protein-coding genes; however, the vast majority of transcripts in humans are non-coding RNAs (ncRNAs) which do not encode proteins. Recently, long non-coding RNAs (lncRNAs) were shown to be highly expressed in the human brain and crucial for normal brain development. We have constructed a computational pipeline for the integration of various genomic datasets to identify lncRNAs associated with ASD. This pipeline utilizes differential gene expression patterns in affected tissues in conjunction with gene co-expression networks in tissue-matched non-affected samples. We analyzed RNA-seq data from the cortical brain tissues from ASD cases and controls to identify lncRNAs differentially expressed in ASD. We derived a gene co-expression network from an independent human brain developmental transcriptome and detected a convergence of the differentially expressed lncRNAs and known ASD risk genes into specific co-expression modules. Co-expression network analysis facilitates the discovery of associations between previously uncharacterized lncRNAs with known ASD risk genes, affected molecular pathways and at-risk developmental time points. In addition, we show that some of these lncRNAs have a high degree of overlap with major CNVs detected in ASD genetic studies. By utilizing this integrative approach comprised of differential expression analysis in affected tissues and connectivity metrics from a developmental co-expression network, we have prioritized a set of candidate ASD-associated lncRNAs. The identification of lncRNAs as novel ASD susceptibility genes could help explain the genetic pathogenesis of ASD.

Interactions Between Genetics, Lifestyle, and Environmental Factors for Healthcare

The occurrence and progression of diseases are strongly associated with a combination of genetic, lifestyle, and environmental factors. Understanding the interplay between genetic and nongenetic components provides deep insights into disease pathogenesis and promotes personalized strategies for people healthcare. Recently, the paradigm of systems medicine, which integrates biomedical data and knowledge at multidimensional levels, is considered to be an optimal way for disease management and clinical decision-making in the era of precision medicine. In this chapter, epigenetic-mediated genetics-lifestyle-environment interactions within specific diseases and different ethnic groups are systematically discussed, and data sources, computational models, and translational platforms for systems medicine research are sequentially presented. Moreover, feasible suggestions on precision healthcare and healthy longevity are kindly proposed based on the comprehensive review of current studies.

Autism genes are selectively targeted by environmental pollutants including pesticides, heavy metals, bisphenol A, phthalates and many others in food, cosmetics or household products

The increasing incidence of autism suggests a major environmental influence. Epidemiology has implicated many candidates and genetics many susceptibility genes. Gene/environment interactions in autism were analysed using 206 autism susceptibility genes (ASG's) from the Autworks database to interrogate ∼1 million chemical/gene interactions in the comparative toxicogenomics database. Any bias towards ASG's was statistically determined for each chemical. Many suspect compounds identified in epidemiology, including tetrachlorodibenzodioxin, pesticides, particulate matter, benzo(a)pyrene, heavy metals, valproate, acetaminophen, SSRI's, cocaine, bisphenol A, phthalates, polyhalogenated biphenyls, flame retardants, diesel constituents, terbutaline and oxytocin, inter alia showed a significant degree of bias towards ASG's, as did relevant endogenous agents (retinoids, sex steroids, thyroxine, melatonin, folate, dopamine, serotonin). Numerous other suspected endocrine disruptors (over 100) selectively targeted ASG's including paraquat, atrazine and other pesticides not yet studied in autism and many compounds used in food, cosmetics or household products, including tretinoin, soy phytoestrogens, aspartame, titanium dioxide and sodium fluoride. Autism polymorphisms influence the sensitivity to some of these chemicals and these same genes play an important role in barrier function and control of respiratory cilia sweeping particulate matter from the airways. Pesticides, heavy metals and pollutants also disrupt barrier and/or ciliary function, which is regulated by sex steroids and by bitter/sweet taste receptors. Further epidemiological studies and neurodevelopmental and behavioural research is warranted to determine the relevance of large number of suspect candidates whose addition to the environment, household, food and cosmetics might be fuelling the autism epidemic in a gene-dependent manner.