Epigenetic Effect of Environmental Factors on Autism Spectrum Disorders

Autism Spectrum Disorder Pathogenesis-A Cross-Sectional Literature Review Emphasizing Molecular Aspects

The etiology of autism spectrum disorder (ASD) has not yet been completely elucidated. Through time, multiple attempts have been made to uncover the causes of ASD. Different theories have been proposed, such as being caused by alterations in the gut-brain axis with an emphasis on gut dysbiosis, post-vaccine complications, and genetic or even autoimmune causes. In this review, we present data covering the main streams that focus on ASD etiology. Data collection occurred in many countries covering ethnically diverse subjects. Moreover, we aimed to show how the progress in genetic techniques influences the explanation of medical White Papers in the ASD area. There is no single evidence-based pathway that results in symptoms of ASD. Patient management has constantly only been symptomatic, and there is no ASD screening apart from symptom-based diagnosis and parent-mediated interventions. Multigene sequencing or epigenetic alterations hold promise in solving the disjointed molecular puzzle. Further research is needed, especially in the field of biogenetics and metabolomic aspects, because young children constitute the patient group most affected by ASD. In summary, to date, molecular research has confirmed multigene dysfunction as the causative factor of ASD, the multigene model with metabolomic influence would explain the heterogeneity in ASD, and it is proposed that ion channel dysfunction could play a core role in ASD pathogenesis.

Decoding the genetic landscape of autism: A comprehensive review

BACKGROUND

Autism spectrum disorder (ASD) is a complex neurodevelopmental condition characterized by heterogeneous symptoms and genetic underpinnings. Recent advancements in genetic and epigenetic research have provided insights into the intricate mechanisms contributing to ASD, influencing both diagnosis and therapeutic strategies.

AIM

To explore the genetic architecture of ASD, elucidate mechanistic insights into genetic mutations, and examine gene-environment interactions.

METHODS

A comprehensive systematic review was conducted, integrating findings from studies on genetic variations, epigenetic mechanisms (such as DNA methylation and histone modifications), and emerging technologies [including Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-Cas9 and single-cell RNA sequencing]. Relevant articles were identified through systematic searches of databases such as PubMed and Google Scholar.

RESULTS

Genetic studies have identified numerous risk genes and mutations associated with ASD, yet many cases remain unexplained by known factors, suggesting undiscovered genetic components. Mechanistic insights into how these genetic mutations impact neural development and brain connectivity are still evolving. Epigenetic modifications, particularly DNA methylation and non-coding RNAs, also play significant roles in ASD pathogenesis. Emerging technologies like CRISPR-Cas9 and advanced bioinformatics are advancing our understanding by enabling precise genetic editing and analysis of complex genomic data.

CONCLUSION

Continued research into the genetic and epigenetic underpinnings of ASD is crucial for developing personalized and effective treatments. Collaborative efforts integrating multidisciplinary expertise and international collaborations are essential to address the complexity of ASD and translate genetic discoveries into clinical practice. Addressing unresolved questions and ethical considerations surrounding genetic research will pave the way for improved diagnostic tools and targeted therapies, ultimately enhancing outcomes for individuals affected by ASD.

Investigating the effect of exposure to monosodium glutamate during pregnancy on development of autism in male rat offspring

In present study, we investigated the relationship between the pregnancy exposure to monosodium glutamate (MSG) and autism development in male offspring of rats. Pregnant Wistar rats were allocated into five groups. The first group was control group that pregnant animals received normal saline orally from day 1-18 of pregnancy. Group 2, 3 and 4 pregnant rats received different doses (1.5, 5 and 10 g/kg) of MSG by the same way respectively. Group 5 received 500 mg/kg of Valproic acid (VPA) on the 12.5th day of pregnancy. Different behavioral tests including marble burying, self-grooming, and Barnes maze test were performed on offspring. The levels of glutamate and GSH markers were also measured. The results showed that MSG similar to VPA led to induction of autistic anxiety and repetitive behaviors. It could also deteriorate the spatial memory. Besides we found that behavioral symptoms potentiated with increasing the MSG dosage. Similarly, we had an increase in glutamate and a reduction in GSH levels in offspring. Findings indicated that MSG was able to induce autism in offspring of rats in a dose-dependent way. This effect could be through increasing of glutamate and reduction of GSH. Consequently, MSG should be avoided during pregnancy.

Brief Report: Evidence of Autism Spectrum Disorder Caused by a Mutation in ATRX Gene: A Case Report

ATRX mutations are commonly associated with alpha-thalassaemia mental retardation syndrome (ATR-X syndrome) with a notable variable expressivity. This X-linked disorder is characterized by intellectual disability (ID) in a higher or lesser degree, in which the alpha-thalassaemia feature is not always present. Other phenotypic manifestations like facial dimorphism, hypotonia, microcephaly, skeletal abnormalities or urogenital malformations have been frequently observed in ATR-X syndrome. Herein, we report a missense ATRX mutation (Thr1621Met) in a patient with an autism spectrum disorder (ASD) diagnosis. Except for ID, no typical signs of ATR-X syndrome were found in the patient. These results confirm the extensive phenotypic variability associated to ATRX mutations and show the involvement of this gene in the ASD.

The early life exposome and autism risk: a role for the maternal microbiome?

Autism spectrum disorders (ASD) are highly heritable, heterogeneous neurodevelopmental disorders characterized by clinical presentation of atypical social, communicative, and repetitive behaviors. Over the past 25 years, hundreds of ASD risk genes have been identified. Many converge on key molecular pathways, from translational control to those regulating synaptic structure and function. Despite these advances, therapeutic approaches remain elusive. Emerging data unearthing the relationship between genetics, microbes, and immunity in ASD suggest an integrative physiology approach could be paramount to delivering therapeutic breakthroughs. Indeed, the advent of large-scale multi-OMIC data acquisition, analysis, and interpretation is yielding an increasingly mechanistic understanding of ASD and underlying risk factors, revealing how genetic susceptibility interacts with microbial genetics, metabolism, epigenetic (re)programming, and immunity to influence neurodevelopment and behavioral outcomes. It is now possible to foresee exciting advancements in the treatment of some forms of ASD that could markedly improve quality of life and productivity for autistic individuals. Here, we highlight recent work revealing how gene X maternal exposome interactions influence risk for ASD, with emphasis on the intrauterine environment and fetal neurodevelopment, host-microbe interactions, and the evolving therapeutic landscape for ASD.

Autism Spectrum Disorder in 2023: A Challenge Still Open

In this paper, we provide an update on autism spectrum disorder (ASD), including epidemiology, etiopathogenesis, clinical presentation, instrumental investigations, early signs, onset patterns, neuropsychological hypotheses, treatments, and long-term outcome. The prevalence of this condition has increased enormously over the last few decades. This increase prompted a search for possible environmental factors whose effects would add up to a genetic predisposition leading to the development of autism. But the genetic and environmental variables involved are extremely numerous, and conclusive data regarding the etiopathogenesis are still far away. Assuming that a well-defined etiology is still found today only in a minority of cases, numerous pathogenetic mechanisms have been hypothesized. Among these, we mention oxidative stress, mitochondrial dysfunction, alteration of the intestinal microbiota, immune dysregulation, and neuroinflammation. These pathogenetic mechanisms could alter epigenetic status and gene expression, finally leading to ASD. Inherent in the term spectrum is the great clinical heterogeneity of this condition, mainly due to the frequent comorbidity that characterizes it. The earlier the diagnosis is made and the earlier psychoeducational treatment begins, the better the prognosis. In this sense, the role of pediatricians can be decisive in making children with signs suggestive of autism undergo a specialist diagnostic course. The development of increasingly advanced cognitive-behavioral educational techniques has considerably improved the prognosis of affected individuals, even though only a small minority of them come off the autistic spectrum. Pharmacological therapies are used to treat comorbidities. During childhood, the most important prognostic factor for long-term outcome seems to be intellectual functioning.

Correlation of mutated gene and signalling pathways in ASD

Autism is a complicated spectrum of neurodevelopmental illnesses characterized by repetitive and constrained behaviors and interests, as well as social interaction and communication difficulties that are first shown in infancy. More than 18 million Indians, according to the National Health Portal of India, and 1 in 160 children worldwide, according to the WHO, are diagnosed with autism spectrum disorders. This review aims to discuss the complex genetic architecture that underlies autism and summarizes the role of proteins likely to play in the development of autism. We also consider how genetic mutations can affect convergent signaling pathways and hinder the development of brain circuitry and the role of cognition development and theory of mind with Cognition-behavior therapy benefits in autism.

Improving Functional Abilities in Children and Adolescents with Autism Spectrum Disorder Using Non-Invasive REAC Neuro Psycho Physical Optimization Treatments: A PEDI-CAT Study

Autism Spectrum Disorder (ASD) is a complex neurodevelopmental disorder that affects communication, social interaction, and behavior. Non-invasive neuromodulation techniques, such as radioelectric asymmetric conveyer (REAC) technology, have gained attention for their potential to improve the endogenous bioelectric activity (EBA) and neurobiological processes underlying ASD. Neuro Postural Optimization (NPO) and Neuro Psycho Physical Optimization (NPPO) treatments are non-invasive and painless neuromodulation treatments that utilize REAC technology and have shown promising results in improving the symptoms of ASD. This study aimed to evaluate the effects of NPO and NPPO treatments on functional abilities in children and adolescents with ASD using the Pediatric Evaluation of Disability Inventory-Computer Adaptive Test (PEDI-CAT). The study consisted of 27 children and adolescents with ASD who underwent a single session of NPO followed by 18 sessions of NPPO treatment over a period of one week. The results showed significant improvements in the children's and adolescents' functional abilities across all domains of the PEDI-CAT. These findings suggest that NPO and NPPO may be effective treatments for improving functional abilities in children and adolescents with ASD.

Candidate biomarkers from the integration of methylation and gene expression in discordant autistic sibling pairs

While the genetics of autism spectrum disorders (ASD) has been intensively studied, resulting in the identification of over 100 putative risk genes, the epigenetics of ASD has received less attention, and results have been inconsistent across studies. We aimed to investigate the contribution of DNA methylation (DNAm) to the risk of ASD and identify candidate biomarkers arising from the interaction of epigenetic mechanisms with genotype, gene expression, and cellular proportions. We performed DNAm differential analysis using whole blood samples from 75 discordant sibling pairs of the Italian Autism Network collection and estimated their cellular composition. We studied the correlation between DNAm and gene expression accounting for the potential effects of different genotypes on DNAm. We showed that the proportion of NK cells was significantly reduced in ASD siblings suggesting an imbalance in their immune system. We identified differentially methylated regions (DMRs) involved in neurogenesis and synaptic organization. Among candidate loci for ASD, we detected a DMR mapping to CLEC11A (neighboring SHANK1) where DNAm and gene expression were significantly and negatively correlated, independently from genotype effects. As reported in previous studies, we confirmed the involvement of immune functions in the pathophysiology of ASD. Notwithstanding the complexity of the disorder, suitable biomarkers such as CLEC11A and its neighbor SHANK1 can be discovered using integrative analyses even with peripheral tissues.

Associations between parental psychiatric disorders and autism spectrum disorder in the offspring

Whether parental psychiatric disorders are associated with autism spectrum disorder (ASD) in offspring has remained inconclusive. We examined the associations of parental psychiatric disorders with ASD in offspring. This population-based case-control study used Taiwan's National Health Insurance Research Database to identify a cohort of children born from 2004 to 2017 and their parents. A total of 24,279 children with ASD (diagnostic ICD-9-CM code: 299.x or ICD-10 code F84.x) and 97,715 matched controls were included. Parental psychiatric disorders, including depressive disorders, bipolar spectrum disorders, anxiety disorders, obsessive-compulsive disorder, schizophrenia, substance use disorders, autism spectrum disorder, attention-deficit hyperactivity disorder (ADHD), and adjustment disorders were identified. Conditional logistic regressions with covariate adjustment were performed. The results suggest that parental diagnosis with any of the psychiatric disorders is associated with ASD in offspring (adjusted odds ratio [AOR] = 1.45, 95%CI: 1.40-1.51 for mothers; and AOR = 1.12, 95%CI: 1.08-1.17 for fathers). ASD in offspring was associated with schizophrenia, depressive disorders, obsessive-compulsive disorder, adjustment disorders, ADHD and ASD in both parents. The relationship between parental psychiatric disorders and the timing of the child's birth and ASD diagnosis varied across the different psychiatric disorders. The present study provides supportive evidence that parental psychiatric disorders are associated with autistic children. Furthermore, because the associations between parental psychiatric disorders and the timing of child's birth and ASD diagnosis varied across psychiatric disorders, the observed relationships may be affected by both genetic and environmental factors. Future studies are needed to disentangle the potential influence of genetic and environmental factors on the observed associations.

Evidence of transgenerational effects on autism spectrum disorder using multigenerational space-time cluster detection

Background

Transgenerational epigenetic risks associated with complex health outcomes, such as autism spectrum disorder (ASD), have attracted increasing attention. Transgenerational environmental risk exposures with potential for epigenetic effects can be effectively identified using space-time clustering. Specifically applied to ancestors of individuals with disease outcomes, space-time clustering characterized for vulnerable developmental stages of growth can provide a measure of relative risk for disease outcomes in descendants.

Objectives

(1) Identify space-time clusters of ancestors with a descendent with a clinical ASD diagnosis and matched controls. (2) Identify developmental windows of ancestors with the highest relative risk for ASD in descendants. (3) Identify how the relative risk may vary through the maternal or paternal line.

Methods

Family pedigrees linked to residential locations of ASD cases in Utah have been used to identify space-time clusters of ancestors. Control family pedigrees of none-cases based on age and sex have been matched to cases 2:1. The data have been categorized by maternal or paternal lineage at birth, childhood, and adolescence. A total of 3957 children, both parents, and maternal and paternal grandparents were identified. Bernoulli space-time binomial relative risk (RR) scan statistic was used to identify clusters. Monte Carlo simulation was used for statistical significance testing.

Results

Twenty statistically significant clusters were identified. Thirteen increased RR (> 1.0) space-time clusters were identified from the maternal and paternal lines at a p-value < 0.05. The paternal grandparents carry the greatest RR (2.86–2.96) during birth and childhood in the 1950’s–1960, which represent the smallest size clusters, and occur in urban areas. Additionally, seven statistically significant clusters with RR < 1 were relatively large in area, covering more rural areas of the state.

Conclusion

This study has identified statistically significant space-time clusters during critical developmental windows that are associated with ASD risk in descendants. The geographic space and time clusters family pedigrees with over 3 + generations, which we refer to as a person’s geographic legacy, is a powerful tool for studying transgenerational effects that may be epigenetic in nature. Our novel use of space-time clustering can be applied to any disease where family pedigree data is available.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12942-022-00313-4.

Epigenetics of Autism Spectrum Disorder: Histone Deacetylases

The etiology of autism spectrum disorder (ASD) remains unknown, but gene-environment interactions, mediated through epigenetic mechanisms, are thought to be a key contributing factor. Prenatal environmental factors have been shown to be associated with both increased risk of ASD and altered histone deacetylases (HDACs) or acetylation levels. The relationship between epigenetic changes and gene expression in ASD suggests that alterations in histone acetylation, which lead to changes in gene transcription, may play a key role in ASD. Alterations in the acetylome have been demonstrated for several genes in ASD, including genes involved in synaptic function, neuronal excitability, and immune responses, which are mechanisms previously implicated in ASD. We review preclinical and clinical studies that investigated HDACs and autism-associated behaviors and discuss risk genes for ASD that code for proteins associated with HDACs. HDACs are also implicated in neurodevelopmental disorders with a known genetic etiology, such as 15q11-q13 duplication and Phelan-McDermid syndrome, which share clinical features and diagnostic comorbidities (e.g., epilepsy, anxiety, and intellectual disability) with ASD. Furthermore, we highlight factors that affect the behavioral phenotype of acetylome changes, including sensitive developmental periods and brain region specificity in the context of epigenetic programming.

Epigenome-Wide Analysis Reveals DNA Methylation Alteration in ZFP57 and Its Target RASGFR2 in a Mexican Population Cohort with Autism

Autism Spectrum Disorders (ASD) comprise a group of heterogeneous and complex neurodevelopmental disorders. Genetic and environmental factors contribute to ASD etiology. DNA methylation is particularly relevant for ASD due to its mediating role in the complex interaction between genotype and environment and has been implicated in ASD pathophysiology. The lack of diversity in DNA methylation studies in ASD individuals is remarkable. Since genetic and environmental factors are likely to vary across populations, the study of underrepresented populations is necessary to understand the molecular alterations involved in ASD and the risk factors underlying these changes. This study explored genome-wide differences in DNA methylation patterns in buccal epithelium cells between Mexican ASD patients (n = 27) and age-matched typically developing (TD: n = 15) children. DNA methylation profiles were evaluated with the Illumina 450k array. We evaluated the interaction between sex and ASD and found a differentially methylated region (DMR) over the 5′UTR region of ZFP57 and one of its targets, RASGRF2. These results match previous findings in brain tissue, which may indicate that ZFP57 could be used as a proxy for DNA methylation in different tissues. This is the first study performed in a Mexican, and subsequently, Latin American, population that evaluates DNA methylation in ASD patients.

Environmental Influences Measured by Epigenetic Clock and Vulnerability Components at Birth Impact Clinical ASD Heterogeneity

Although Autism Spectrum Disorders (ASD) is recognized as being heavily influenced by genetic factors, the role of epigenetic and environmental factors is still being established. This study aimed to identify ASD vulnerability components based on familial history and intrauterine environmental stress exposure, explore possible vulnerability subgroups, access DNA methylation age acceleration (AA) as a proxy of stress exposure during life, and evaluate the association of ASD vulnerability components and AA to phenotypic severity measures. Principal Component Analysis (PCA) was used to search the vulnerability components from 67 mothers of autistic children. We found that PC1 had a higher correlation with psychosocial stress (maternal stress, maternal education, and social class), and PC2 had a higher correlation with biological factors (psychiatric family history and gestational complications). Comparing the methylome between above and below PC1 average subgroups we found 11,879 statistically significant differentially methylated probes (DMPs, p < 0.05). DMPs CpG sites were enriched in variably methylated regions (VMRs), most showing environmental and genetic influences. Hypermethylated probes presented higher rates in different regulatory regions associated with functional SNPs, indicating that the subgroups may have different affected regulatory regions and their liability to disease explained by common variations. Vulnerability components score moderated by epigenetic clock AA was associated with Vineland Total score (p = 0.0036, adjR² = 0.31), suggesting risk factors with stress burden can influence ASD phenotype.

Influence of the Aryl Hydrocarbon Receptor Activating Environmental Pollutants on Autism Spectrum Disorder

Autism spectrum disorder (ASD) is an umbrella term that includes many different disorders that affect the development, communication, and behavior of an individual. Prevalence of ASD has risen exponentially in the past couple of decades. ASD has a complex etiology and traditionally recognized risk factors only account for a small percentage of incidence of the disorder. Recent studies have examined factors beyond the conventional risk factors (e.g., environmental pollution). There has been an increase in air pollution since the beginning of industrialization. Most environmental pollutants cause toxicities through activation of several cellular receptors, such as the aryl hydrocarbon receptor (AhR)/cytochrome P450 (CYPs) pathway. There is little research on the involvement of AhR in contributing to ASD. Although a few reviews have discussed and addressed the link between increased prevalence of ASD and exposure to environmental pollutants, the mechanism governing this effect, specifically the role of AhR in ASD development and the molecular mechanisms involved, have not been discussed or reviewed before. This article reviews the state of knowledge regarding the impact of the AhR/CYP pathway modulation upon exposure to environmental pollutants on ASD risk, incidence, and development. It also explores the molecular mechanisms involved, such as epigenesis and polymorphism. In addition, the review explores possible new AhR-mediated mechanisms of several drugs used for treatment of ASD, such as sulforaphane, resveratrol, haloperidol, and metformin.

Awareness and perception of medical genetic services among Malaysian parents of autism spectrum disorders children: the lessons to be learned

Purpose

Autism spectrum disorder (ASD) is a group of complex neurodevelopmental disorders with uncertain etiology. Evidence shows that genetic testing can explain about 20% of cases. This study aims to assess the level of awareness and perception of medical genetic services among Malaysian parents with ASD children.

Design/methodology/approach

A cross-sectional survey using an interviewer-administered questionnaire was done among 111 parents of children with ASD from August 2017 to September 2019 in two clinics in Malaysia.

Findings

A majority of children with ASD (80.20%) were male and diagnosed at the age of 3–4 years old (47.80%). When the autistic child was born, most mothers and fathers were aged 26–30 (40.50%) and 31–35 years old (42.30%), respectively. Another child with ASD in nuclear and extended families was reported for 11.70% and 13.50%, respectively. Only 24.30% have seen a professional genetic consultant, and 19.8% have done genetic testing for affected children. The mean score of awareness of genetic services for ASD was 2.48 ± 3.30. Having medical insurance and another child with ASD in the nuclear family was significantly associated with a higher level of awareness (p = 0.01 and p < 0.001, respectively). Most of the participants have a positive perception of these services.

Originality/value

Regardless of demographic factors, participants have poor awareness of genetic services for ASD, likely because the primary physician did not recommend it upon diagnosis. Increasing health-care providers’ knowledge about the current potential of genetic testing for ASD and educational campaigns for the public are critical components of using available genetic tests to improve ASD management.

[Genetic risk factors and their influence on neural development in autism spectrum disorders]

Genetic risk factors and their influence on neural development in autism spectrum disorders Abstract. Abstract. Autism spectrum disorders are etiologically based on genetic and specific gene x biologically relevant environmental risk factors. They are diagnosed based on behavioral characteristics, such as impaired social communication and stereotyped, repetitive behavior and sensory as well as special interests. The genetic background is heterogeneous, i. e., it comprises diverse genetic risk factors across the disorder and high interindividual differences of specific genetic risk factors. Nevertheless, risk factors converge regarding underlying biological mechanisms and shared pathways, which likely cause the autism-specific behavioral characteristics. The current selective literature review summarizes differential genetic risk factors and focuses particularly on mechanisms and pathways currently being discussed by international research. In conclusion, clinically relevant aspects and open translational research questions are presented.

The epigenetic regulation of synaptic genes contributes to the etiology of autism

Epigenetic mechanisms greatly affect the developing brain, as well as the maturation of synapses with pervasive, long-lasting consequences on behavior in adults. Substantial evidence exists that implicates dysregulation of epigenetic mechanisms in the etiology of neurodevelopmental disorders. Therefore, this review explains the role of enzymes involved in DNA methylation and demethylation in neurodevelopment by emphasizing changes of synaptic genes and proteins. Epigenetic causes of sex-dependent differences in the brain are analyzed in conjunction with the pathophysiology of autism spectrum disorders. Special attention is devoted to the epigenetic regulation of the melanoma-associated antigen-like gene 2 (MAGEL2) found in Prader-Willi syndrome, which is known to be accompanied by autistic symptoms.

Social epigenomics: are we at an impasse?

Aim: Social scientists have placed particularly high expectations on the study of epigenomics to explain how exposure to adverse social factors like poverty, child maltreatment and racism - particularly early in childhood - might contribute to complex diseases. However, progress has stalled, reflecting many of the same challenges faced in genomics, including overhype, lack of diversity in samples, limited replication and difficulty interpreting significance of findings. Materials & methods: This review focuses on the future of social epigenomics by discussing progress made, ongoing methodological and analytical challenges and suggestions for improvement. Results & conclusion: Recommendations include more diverse sample types, cross-cultural, longitudinal and multi-generational studies. True integration of social and epigenomic data will require increased access to both data types in publicly available databases, enhanced data integration frameworks, and more collaborative efforts between social scientists and geneticists.

Genetic and Epigenetic Etiology Underlying Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a pervasive neurodevelopmental disorder characterized by difficulties in social interaction, language development delays, repeated body movements, and markedly deteriorated activities and interests. Environmental factors, such as viral infection, parental age, and zinc deficiency, can be plausible contributors to ASD susceptibility. As ASD is highly heritable, genetic risk factors involved in neurodevelopment, neural communication, and social interaction provide important clues in explaining the etiology of ASD. Accumulated evidence also shows an important role of epigenetic factors, such as DNA methylation, histone modification, and noncoding RNA, in ASD etiology. In this review, we compiled the research published to date and described the genetic and epigenetic epidemiology together with environmental risk factors underlying the etiology of the different phenotypes of ASD.

Analysis of lead, arsenic and calcium content in the hair of children with autism spectrum disorder

BACKGROUND

Explanation of the pathogenesis and treatment of autism spectrum disorders (ASD) is one of the most significant challenges for scientists today. It is believed that a major pathogenetic factor of this condition is epigenetic changes caused by environmental factors, including toxic metals (cadmium (Cd), lead (Pb), mercury (Hg), aluminium (Al), and arsenic (As)). The nervous system may also be affected by deficiencies of both micro- and macroelements (e.g. calcium (Ca), zinc (Zn)). The aim of the study was to analyze the concentrations of Pb, As, and Ca in the hair of children with ASD and a control group.

METHODS

The materials for the study comprised hair samples collected from 30 children diagnosed with ASD (case group) and 30 children randomly selected from the general population of Bialystok and surrounding region (control group). Concentrations of Pb, As, and Ca were tested with electron microscopy scanning method. Next, the content of the analyzed elements in the hair was assessed as well as their impact on autism development in the children and the mutual interactions between them. The obtained results were statistically analyzed with Statistica PL 12.5., using the Mann-Whitney U test, and Spearman correlation coefficient.

RESULTS

Mean Ca level in the hair of the case group was lower than the mean level of this element in the control group. Mean As and Pb concentration in the hair of children with ASD was statistically significantly higher than the mean concentration of this element in the hair of children without neurological disorders. Statistically insignificant weak positive correlations between Ca and As content and negative between Ca and Pb in the hair of children from the case group were noted. Also, statistically significant mean positive correlations between Pb and As were observed.

CONCLUSIONS

In this small study, according to the observations, children diagnosed with ASD suffer from Ca deficiency and toxic metal overload (As and Pb). These abnormalities may play the main role, as an environmental factor, in the pathogenesis of the analyzed disorder.

New Horizons for Molecular Genetics Diagnostic and Research in Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a highly heritable, heterogeneous, and complex pervasive neurodevelopmental disorder (PND) characterized by distinctive abnormalities of human cognitive functions, social interaction, and speech development.Nowadays, several genetic changes including chromosome abnormalities, genetic variations, transcriptional epigenetics, and noncoding RNA have been identified in ASD. However, the association between these genetic modifications and ASDs has not been confirmed yet.The aim of this review is to summarize the key findings in ASD from genetic viewpoint that have been identified from the last few decades of genetic and molecular research.

Genes Positively Selected in Domesticated Mammals Are Significantly Dysregulated in the Blood of Individuals with Autism Spectrum Disorders

Human self-domestication (i.e., the presence of traits in our species that are commonly found in domesticated animals) has been hypothesized to have contributed to the emergence of many human-specific features, including aspects of our cognition and behavior. Signs of self-domestication have been claimed to be attenuated in individuals with autism spectrum disorders (ASD), this conceivably accounting for facets of their distinctive cognitive and behavioral profile, although this possibility needs to be properly tested. In this study, we have found that candidate genes for mammal domestication, but not for neural crest development and function, are significantly dysregulated in the blood of subjects with ASD. The set of differentially expressed genes (DEGs) is enriched in biological and molecular processes, as well as in pathological phenotypes, of relevance for the etiology of ASD, like lipid metabolism, cell apoptosis, the activity of the insulin-like growth factor, gene expression regulation, skin/hair anomalies, musculoskeletal abnormalities, and hearing impairment. Moreover, among the DEGs, there are known candidates for ASD and/or genes involved in biological processes known to be affected in ASD. Our findings give support to the view that one important aspect of the etiopathogenesis of ASD is the abnormal manifestation of features of human self-domestication.

Genetic Causes and Modifiers of Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is one of the most prevalent neurodevelopmental disorders, affecting an estimated 1 in 59 children. ASD is highly genetically heterogeneous and may be caused by both inheritable and de novo gene variations. In the past decade, hundreds of genes have been identified that contribute to the serious deficits in communication, social cognition, and behavior that patients often experience. However, these only account for 10-20% of ASD cases, and patients with similar pathogenic variants may be diagnosed on very different levels of the spectrum. In this review, we will describe the genetic landscape of ASD and discuss how genetic modifiers such as copy number variation, single nucleotide polymorphisms, and epigenetic alterations likely play a key role in modulating the phenotypic spectrum of ASD patients. We also consider how genetic modifiers can alter convergent signaling pathways and lead to impaired neural circuitry formation. Lastly, we review sex-linked modifiers and clinical implications. Further understanding of these mechanisms is crucial for both comprehending ASD and for developing novel therapies.

Bergamot Aromatherapy for Medical Office-Induced Anxiety Among Children With an Autism Spectrum Disorder: A Randomized, Controlled, Blinded Clinical Trial

This randomized, blinded clinical trial evaluated the effects of aromatherapy on medical office-induced anxiety in children with an autism spectrum disorder. Patients awaiting office visits were randomized into an aromatherapy group and a control group. After adjusting for baseline scores, there was no significant difference between the 2 groups.

Inferring and modeling inheritance of differentially methylated changes across multiple generations

High-throughput methylation sequencing enables genome-wide detection of differentially methylated sites (DMS) or regions (DMR). Increasing evidence suggests that treatment-induced DMS can be transmitted across generations, but the analysis of induced methylation changes across multiple generations is complicated by the lack of sound statistical methods to evaluate significance levels. Due to software design, DMS detection was usually made on each generation separately, thus disregarding stochastic effects expected when a large number of DMS is detected in each generation. Here, we present a novel method based on Monte Carlo sampling, methylInheritance, to evaluate that the number of conserved DMS between several generations is associated to an effect inherited from a treatment and not randomness. Moreover, we developed an inheritance simulation package, methInheritSim, to demonstrate the performance of the methylInheritance method and to evaluate the power of different experimental designs. Finally, we applied methylInheritance to a DNA methylation dataset obtained from early-life persistent organic pollutants (POPs) exposed Sprague-Dawley female rats and their descendants through a paternal transmission. The results show that metylInheritance can efficiently identify treatment-induced inherited methylation changes. Specifically, we identified two intergenerationally conserved DMS at transcription start site (TSS); one of those persisted transgenerationally. Three transgenerationally conserved DMR were found at intra or integenic regions.

The role of epigenetic modifications in neurodevelopmental disorders: A systematic review

Epigenetic processes have been suggested as key mechanisms in the etiology of neurodevelopmental disorders. This systematic review summarizes the current evidence for an association between epigenetics and Autism Spectrum Disorder (ASD) and Attention/Deficit-Hyperactivity Disorder (ADHD). Six databases were searched until the 24th of October 2017. Of the 2169 retrieved articles, 29 met our inclusion criteria. While generally associations between epigenetics and neurodevelopmental disorders were reported, only a few findings were consistent across independent analyses. Differential epigenetic markers were repeatedly identified in OR2L13, C11orf21/TSPAN32, PRRT1 and H3K27 for autism, and in VIPR2 for ADHD. Overall, evidence of an association between epigenetic modifications and ASD or ADHD should be considered preliminary and based on studies suffering from numerous caveats. We highlight the need for carefully designed investigations and for greater homogeneity and provide specific recommendations for future research. Despite the current limited understanding, the suggestive findings and rapid advances in the field hold the promise of a forthcoming elucidation of the role of epigenetic modifications in neurodevelopmental disorders.

Genetics and epigenetics of autism: A Review

Autism is a developmental disorder that starts before age 3 years, and children with autism have impairment in both social interaction and communication, and have restricted, repetitive, and stereotyped patterns of behavior, interests, and activities. There is a strong heritable component of autism and autism spectrum disorder (ASD) as studies have shown that parents who have a child with ASD have a 2-18% chance of having a second child with ASD. The prevalence of autism and ASD have been increasing during the last 3 decades and much research has been carried out to understand the etiology, so as to develop novel preventive and treatment strategies. This review aims at summarizing the latest research studies related to autism and ASD, focusing not only on the genetics but also some epigenetic findings of autism/ASD. Some promising areas of research using transgenic/knockout animals and some ideas related to potential novel treatment and prevention strategies will be discussed.

Understanding environmental contributions to autism: Causal concepts and the state of science

The complexity of neurodevelopment, the rapidity of early neurogenesis, and over 100 years of research identifying environmental influences on neurodevelopment serve as backdrop to understanding factors that influence risk and severity of autism spectrum disorder (ASD). This Keynote Lecture, delivered at the May 2016 annual meeting of the International Society for Autism Research, describes concepts of causation, outlines the trajectory of research on nongenetic factors beginning in the 1960s, and briefly reviews the current state of this science. Causal concepts are introduced, including root causes; pitfalls in interpreting time trends as clues to etiologic factors; susceptible time windows for exposure; and implications of a multi-factorial model of ASD. An historical background presents early research into the origins of ASD. The epidemiologic literature from the last fifteen years is briefly but critically reviewed for potential roles of, for example, air pollution, pesticides, plastics, prenatal vitamins, lifestyle and family factors, and maternal obstetric and metabolic conditions during her pregnancy. Three examples from the case-control CHildhood Autism Risks from Genes and the Environment Study are probed to illustrate methodological approaches to central challenges in observational studies: capturing environmental exposure; causal inference when a randomized controlled clinical trial is either unethical or infeasible; and the integration of genetic, epigenetic, and environmental influences on development. We conclude with reflections on future directions, including exposomics, new technologies, the microbiome, gene-by-environment interaction in the era of -omics, and epigenetics as the interface of those two. As the environment is malleable, this research advances the goal of a productive and fulfilling life for all children, teen-agers and adults. Autism Res 2018, 11: 554-586. © 2018 International Society for Autism Research, Wiley Periodicals, Inc.

LAY SUMMARY

This Keynote Lecture, delivered at the 2016 meeting of the International Society for Autism Research, discusses evidence from human epidemiologic studies of prenatal factors contributing to autism, such as pesticides, maternal nutrition and her health. There is no single cause for autism. Examples highlight the features of a high-quality epidemiology study, and what comprises a compelling case for causation. Emergent research directions hold promise for identifying potential interventions to reduce disabilities, enhance giftedness, and improve lives of those with ASD.

Transcriptional and splicing dysregulation in the prefrontal cortex in valproic acid rat model of autism

Gene-environmental interaction could be the major cause of autism. The aim of the current study is to detect the effects of valproic acid on gene expression profiles and alternatively spliced genes in the prefrontal cortex in rat models of autism. Female rats received a single intraperitoneal injection of 600 mg/kg valproic acid at day 12.5 post-conception, and controls were injected with saline. Only male offspring were employed in the current study. RNA sequencing was used to investigate transcriptome in the prefrontal cortex of VPA-exposed rats. There were 3228 differently expressed genes and 637 alternative spliced genes, in VPA rats compared to controls. Pathways enrichment among the differently expressed genes and alternatively spliced genes were associated with neurological diseases and neural system development. The results implied VPA affected transcriptional and splicing events genome-wide and the transcriptional and splicing events may be associated with the autistic behaviors of VPA rats.

Current status of biological treatment options in Autism Spectrum Disorder

Autism Spectrum Disorders (ASDs) are characterised by deficits in social communication and restricted and repetitive behaviours. With an onset in early childhood, ASDs are thought to be heterogeneous, both genetically and clinically. This has led to the notion that "autism" is "autisms", however, there has been limited progress in understanding the different subgroups and the unique pathogenesis that would then allow targeted intervention. Although existing treatments are mainly symptom focussed, research is beginning to unravel the underlying genetic and molecular pathways, structural and functional neuronal circuitry involvement and the associated neurochemicals. This paper will review selected biological models with regard to pharmacological targets while also covering some of the non-pharmacological treatments such as neuro-stimulation.

Impaired Redox Control in Autism Spectrum Disorders: Could It Be the X in GxE?

PURPOSE OF REVIEW

This review aims to provide a brief description of the complex etiology of autism spectrum disorders (ASD), with special emphasis on the recent findings of impaired redox control in ASD, and to suggest a possible model of oxidative stress-specific gene-environment interaction in this group of disorders.

RECENT FINDINGS

Recent findings point out to the significance of environmental, prenatal, and perinatal factors in ASD but, at the same time, are in favor of the potentially significant oxidative stress-specific gene-environment interaction in ASD. Available evidence suggests an association between both the identified environmental factors and genetic susceptibility related to the increased risk of ASD and the oxidative stress pathway. There might be a potentially significant specific gene-environment interaction in ASD, which is associated with oxidative stress. Revealing novel susceptibility genes (including those encoding for antioxidant enzymes), or environmental factors that might increase susceptibility to ASD in carriers of a specific genotype, might enable the stratification of individuals more prone to developing ASD and, eventually, the possibility of applying preventive therapeutic actions.

A rapid chemical-genetic screen utilizing impaired movement phenotypes in C. elegans: Input into genetics of neurodevelopmental disorders

Autism spectrum disorder (ASD) is the most common neurodevelopmental disorder with a constantly increasing prevalence. Model organisms may be tools to identify underlying cellular and molecular mechanisms, as well as aid the discovery and development of novel therapeutic approaches. A simple animal such as the nematode Caenorhabditis elegans may provide insights into the extreme complexity of ASD genetics. Despite its potential, using C. elegans in ASD research is a controversial approach and has not yet been used extensively in this context. In this study, we present a screening approach of potential C. elegans mutants as potential ASD models. We screened these mutants for motor-deficiency phenotypes, which can be exploited to study underlying mechanisms of the disorder. Selected motor-deficient mutants were then used in a comprehensive drug screen of over 3900 compounds, including many FDA-approved and natural molecules, that were analyzed for their ability to suppress motility defects caused by ASD-associated gene orthologues. This genetic-chemical approach, i.e. establishing C. elegans models for ASD and screening of a well-characterized compound library, might be a promising first step to understand the mechanisms of how gene variations cause neuronal dysfunction, leading to ASD and other neurological disorders. Positively acting compounds could also be promising candidates for preclinical studies.

Autism in 2016: the need for answers

OBJECTIVE

Autism spectrum disorders are lifelong and often devastating conditions that severely affect social functioning and self-sufficiency. The etiopathogenesis is presumably multifactorial, resulting from a very complex interaction between genetic and environmental factors. The dramatic increase in autism spectrum disorder prevalence observed during the last decades has led to placing more emphasis on the role of environmental factors in the etiopathogenesis. The objective of this narrative biomedical review was to summarize and discuss the results of the most recent and relevant studies about the environmental factors hypothetically involved in autism spectrum disorder etiopathogenesis.

SOURCES

A search was performed in PubMed (United States National Library of Medicine) about the environmental factors hypothetically involved in the non-syndromic autism spectrum disorder etiopathogenesis, including: air pollutants, pesticides and other endocrine-disrupting chemicals, electromagnetic pollution, vaccinations, and diet modifications.

SUMMARY OF THE FINDINGS

While the association between air pollutants, pesticides and other endocrine-disrupting chemicals, and risk for autism spectrum disorder is receiving increasing confirmation, the hypothesis of a real causal relation between them needs further data. The possible pathogenic mechanisms by which environmental factors can lead to autism spectrum disorder in genetically predisposed individuals were summarized, giving particular emphasis to the increasingly important role of epigenetics.

CONCLUSIONS

Future research should investigate whether there is a significant difference in the prevalence of autism spectrum disorder among nations with high and low levels of the various types of pollution. A very important goal of the research concerning the interactions between genetic and environmental factors in autism spectrum disorder etiopathogenesis is the identification of vulnerable populations, also in view of proper prevention.

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.