Investigation of the Genetic and Environmental Causes of Autism: a Multi-Center Study

Overview

The goal of this observational study is to investigate the genetic and epigenetic mechanisms that may contribute to the development of Autism Spectrum Disorder (ASD) in individuals of different age groups. The study aims to explore how genetic variants and environmental factors interact to influence the risk of ASD. The main questions it aims to answer are: * Which genetic variants are most strongly associated with the development of ASD? * How do environmental factors, such as prenatal exposure, influence these genetic risks? * Can the combination of genetic and epigenetic data improve early detection or intervention strategies for ASD? Participants will: * Provide biological samples for genetic and epigenetic analysis. * Complete detailed questionnaires regarding environmental exposures and family history. * Participate in clinical assessments to evaluate the severity of ASD symptoms. Researchers will compare genetic and environmental data between individuals with ASD and those without the disorder to understand how these factors may contribute to the risk of ASD. This multi-center study will take place across several universities and hospitals in Türkiye, focusing on the potential interplay between inherited genetic factors and environmental influences.

Introduction to the Project The project represents an innovative, multi-center study aimed at investigating the genetic, epigenetic, and environmental underpinnings of Autism Spectrum Disorder (ASD). ASD is a complex neurodevelopmental condition that typically presents in early childhood and affects individuals in diverse ways, particularly in social communication and behavior. The disorder is marked by significant variability in symptom severity and presentation across individuals. Despite years of research, the molecular mechanisms driving the onset and progression of ASD remain elusive, making diagnosis and treatment challenging. This research aims to fill this gap by using a multi-omics approach to better understand the biological, genetic, and environmental factors contributing to ASD. Through the integration of genomic, epigenomic, and transcriptomic data, the project seeks to uncover molecular signatures and interactions that could explain the variability in ASD presentation and severity. Additionally, the study aims to identify potential biomarkers that could lead to earlier diagnosis, better prognosis, and more personalized treatment options. The study will be conducted across multiple research centers, with a structured and well-coordinated approach to data collection, sample processing, and analysis. This multi-disciplinary project brings together a range of expertise, including genetics, bioinformatics, clinical psychiatry, and data science, ensuring that all aspects of the research are approached with scientific rigor and precision. By analyzing samples from individuals with ASD, the project will provide new insights into the genetic and epigenetic factors involved in ASD, while also investigating the potential influence of environmental factors. Multi-Departmental Structure and Project Integrity The project is organized into multiple specialized departments, each with a specific role in maintaining the integrity of the study and ensuring that all research activities are conducted to the highest standards. This structure allows for seamless collaboration between departments and ensures that all data is collected, processed, and analyzed with the utmost accuracy. Overall Coordination and Oversight At the highest level, the project is managed by an overall coordinator who oversees all aspects of the research. This coordinator ensures that each department adheres to the project's goals and timeline, fostering communication between teams and facilitating the integration of clinical, genetic, and epigenetic data. Coordination ensures that any challenges arising in the course of the study are promptly addressed and that the project remains on track to meet its objectives. The role of the overall coordinator is critical for ensuring the integration of the multi-omics data from the various research centers. The coordinator also plays a key part in the interpretation of data, working closely with the data analysis teams to ensure that the findings are cohesive and meaningful. Regular updates are shared across departments to maintain alignment with the project's overarching research goals. Clinical Operations: Adult and Pediatric Units The clinical operations of the project are divided into two main sectors: adult and pediatric. Each sector is managed by a dedicated team that oversees clinical centers responsible for data collection. These clinical centers are located across various regions, enabling the project to gather a broad and diverse range of clinical data from individuals diagnosed with ASD. Each clinical center follows standardized protocols for data collection, ensuring that all patient data is collected in a uniform and consistent manner. The data collection process involves the use of internationally recognized diagnostic tools, including the Autism Diagnostic Observation Schedule (ADOS) and the Social Communication Questionnaire (SCQ). These tools are essential for diagnosing ASD and for evaluating the severity of symptoms. The clinical operations also involve the collection of sociodemographic data, developmental histories, and information on comorbid conditions. This data is gathered through questionnaires and clinical interviews conducted by trained healthcare professionals. The collection of this comprehensive dataset is critical for understanding the clinical heterogeneity of ASD and for correlating clinical symptoms with genetic and environmental data. Genetic and Omics Divisions The genetic and omics divisions form the core of the project, providing the molecular data that will be used to uncover the genetic and epigenetic mechanisms driving ASD. The division oversees the collection, processing, and analysis of biological samples, which include venous blood and nasal swabs obtained from study participants. Sample Collection and Processing The biological samples collected from participants undergo a rigorous and standardized process of nucleic acid extraction. This process, managed by the nucleic acid extraction and purification teams, involves isolating high-quality DNA and RNA from the blood and nasal swab samples. These samples are essential for downstream sequencing and analyses. The quality of the extracted DNA and RNA is critical, as any impurities or degradation could affect the accuracy of the genetic and epigenetic analyses. Once extracted, the DNA and RNA samples are subjected to multiple quality control checks. These checks are overseen by the quality control and storage teams, who ensure that the nucleic acids meet the required standards for sequencing. Samples that pass the quality control checks are stored under optimal conditions, preserving their integrity until they are ready to be sequenced. Genomic Analysis The genomic analysis of DNA samples begins with whole genome sequencing (WGS), a comprehensive technique that allows researchers to examine the entire genetic code of each participant. WGS enables the identification of a wide range of genetic variants, including single nucleotide polymorphisms (SNPs), copy number variations (CNVs), insertions and deletions (InDels), and structural variants. These variants are evaluated to determine their potential contribution to ASD. One of the primary analyses conducted within the genomic division is the genome-wide association study (GWAS). GWAS is used to identify genetic variants that are significantly associated with ASD by comparing the frequency of variants between individuals with ASD and those without the disorder. This analysis is particularly useful for identifying common genetic variants that may contribute to ASD risk. In addition to GWAS, the project also conducts quantitative trait locus (QTL) analysis. QTL analysis examines how genetic variants influence quantitative traits related to ASD, such as symptom severity, cognitive functioning, or developmental milestones. This type of analysis helps to elucidate the genetic basis for phenotypic variability in ASD and identifies specific variants that may contribute to differences in symptom presentation. Epigenetic Analysis The epigenetic component of the project focuses on how environmental factors influence gene expression and contribute to the risk of ASD. DNA methylation is one of the key epigenetic mechanisms studied in this project. Using whole genome bisulfite sequencing (WGBS), researchers analyze DNA methylation patterns across the entire genome. WGBS is considered the gold standard for high-resolution DNA methylation analysis, allowing the identification of methylation changes that are associated with ASD. Differentially methylated regions (DMRs) are genomic regions where the methylation levels differ between individuals with ASD and unaffected controls. By identifying these DMRs, researchers can pinpoint specific genomic regions where environmental factors may be influencing gene expression in individuals with ASD. Additionally, allele-specific methylation (ASM) is explored in this study. ASM analysis investigates how methylation patterns differ between the two copies of a gene inherited from each parent. This analysis helps researchers understand how genetic and epigenetic factors interact to influence gene expression and contribute to ASD risk. As part of the epigenetic analysis, m-QTL (methylation quantitative trait loci) analysis will be conducted to investigate the relationship between genetic variants and DNA methylation patterns across the genome. m-QTLs are genomic loci where variations in DNA sequence are associated with differences in DNA methylation levels. By identifying these loci, the project aims to uncover how genetic variation influences epigenetic regulation and, subsequently, how these interactions may contribute to the risk of developing ASD. This analysis will provide valuable insights into the interplay between genetic and epigenetic factors, helping to elucidate the molecular mechanisms that underpin ASD. Additionally, m-QTLs may serve as potential biomarkers for understanding the environmental modulation of genetic susceptibility in individuals with ASD. The epigenetic data is also integrated with genetic data to conduct epigenome-wide association studies (EWAS). EWAS examines how DNA methylation patterns correlate with ASD, with the goal of identifying methylation marks that could serve as biomarkers for the disorder. These analyses are essential for understanding how environmental exposures, such as prenatal stress, toxins, or maternal health, may affect ASD risk through epigenetic mechanisms. Transcriptomic Analysis The transcriptomic analysis focuses on understanding how gene expression differs between individuals with ASD and those without the disorder. RNA sequencing (RNA-seq) is used to measure the levels of gene expression in both blood and nasal swab samples. RNA-seq provides a comprehensive view of the transcriptome, which represents the complete set of RNA transcripts present in a cell or tissue at a given time. The RNA-seq data is used to perform differential gene expression (DGE) analysis, which identifies genes that are either upregulated or downregulated in individuals with ASD. This analysis helps to uncover the molecular pathways that are disrupted in ASD and highlights potential biomarkers that could be used for early diagnosis or treatment. In addition to identifying differentially expressed genes, the transcriptomic data is used to perform pathway analysis. Pathway analysis examines how changes in gene expression affect biological processes and cellular functions. This analysis can identify key pathways that may be disrupted in ASD, providing insights into the biological mechanisms underlying the disorder. By comparing the gene expression profiles from both blood and nasal swab samples, researchers can identify tissue-specific expression patterns. This comparison provides a more nuanced understanding of the molecular differences between tissues and may reveal tissue-specific biomarkers for ASD. eQTL (Expression Quantitative Trait Loci) Analysis In addition to m-QTL analysis, integrating eQTL (expression quantitative trait loci) analysis will allow the project to identify genetic variants that affect gene expression levels. eQTLs are loci where genetic variations are correlated with changes in gene expression. By analyzing eQTLs, the study can investigate how specific genetic variants influence the transcription of genes related to ASD. This approach helps uncover regulatory pathways and gene networks that contribute to the variability in ASD symptoms. The integration of eQTL analysis with transcriptomic data (such as RNA-Seq) provides a nuanced understanding of how genetic risk factors alter gene expression, ultimately impacting the phenotypic manifestation of ASD. Epitranscriptomic Analysis Beyond the study of DNA and RNA through genomics and transcriptomics, epitranscriptomics explores post-transcriptional modifications of RNA, such as N6-methyladenosine (m6A). These RNA modifications can impact mRNA stability, splicing, transport, and translation, thus influencing protein production and cell function. Including epitranscriptomic analysis as part of the RNA-Seq workflow will offer insights into how RNA modifications differ in ASD patients, providing an additional layer of gene regulation that contributes to the complexity of ASD. This investigation could uncover novel epitranscriptomic biomarkers for ASD, adding depth to the study's exploration of gene regulation at the RNA level. Data Integration and Bioinformatics The integration of the genomic, epigenomic, and transcriptomic data is a key component of the project. The bioinformatics and data analysis teams are responsible for processing and analyzing the vast amounts of data generated by the omics divisions. This involves the use of advanced bioinformatics tools and statistical models to integrate the data and uncover meaningful patterns. The integrated dataset is subjected to multivariate regression models, which examine the interactions between genetic variants, epigenetic modifications, and gene expression levels. These models are used to identify how these factors jointly contribute to ASD risk and symptom severity. By incorporating both genetic and environmental data, the models can also explore gene-environment interactions that may play a role in the development of ASD. Network analysis is another key tool used by the bioinformatics team. This technique visualizes the interactions between genes, proteins, and regulatory elements, allowing researchers to identify key genes and pathways that may be involved in ASD. Network analysis also helps to uncover gene regulatory networks that may be disrupted in individuals with ASD, providing insights into the molecular mechanisms that drive the disorder. The project also leverages machine learning (ML) and artificial intelligence (AI) algorithms to analyze the data. These predictive models are designed to assist clinicians in making personalized treatment decisions based on the molecular profile of each patient. For example, AI models may be used to predict the severity of ASD symptoms based on genetic, epigenetic, and clinical data, allowing for more targeted interventions. Hi-C and In-Silico Analysis: While traditional Hi-C analysis often uses crosslinkers to capture long-range chromatin interactions, this project will take a distinct approach by forgoing the use of crosslinkers to link specific DNA fragments. Instead, the chromatin interaction data will be derived and revisited in-silico post-data integration. By analyzing the 3D chromatin architecture computationally, the project will aim to identify spatial chromatin interactions that contribute to the regulation of ASD-associated genes. This post-integration approach allows for the identification of regulatory elements, such as enhancers and promoters, that interact with distant genomic regions in the context of ASD. The data generated from the genomic, epigenomic, and transcriptomic analyses will be integrated to reveal chromatin interaction patterns that influence gene expression, particularly those associated with ASD pathology. This strategy will allow for a more flexible and refined understanding of 3D genome organization without the limitations imposed by crosslinker-based methods. ChIP-Seq and In-Silico Epigenetic Pathogenesis Analysis: In addition to chromatin interaction mapping, ChIP-Seq data will be utilized for epigenetic pathogenesis analysis. By performing in-silico analysis of ChIP-Seq results, the project will identify histone modifications and transcription factor binding sites that are involved in the regulation of gene expression in ASD. This technique will help elucidate the roles of specific epigenetic marks, such as histone acetylation and methylation, in the dysregulation of ASD-associated genes. The integration of ChIP-Seq data with other omics data, including DNA methylation (WGBS) and RNA-Seq expression profiles, will provide a comprehensive view of the regulatory networks driving ASD. This will allow researchers to pinpoint specific regulatory mechanisms, such as altered transcription factor activity or changes in chromatin accessibility, that may contribute to the onset or severity of ASD symptoms. In-silico analysis of the ChIP-Seq results will thus serve as a powerful tool for understanding the epigenetic landscape associated with ASD pathogenesis. The project can further enhance its analysis by calculating polygenic risk scores (PRS), which quantify the cumulative effect of numerous small-effect genetic variants on the risk of developing ASD. By aggregating data from thousands of genetic variants, PRS can predict an individual's overall genetic predisposition to ASD. These scores can then be correlated with clinical and phenotypic data to better understand how genetic risk translates into observable symptoms. PRS can also be integrated with environmental and epigenetic data to explore gene-environment interactions, offering a comprehensive model of ASD susceptibility. Quality Control and Compliance Maintaining the integrity of the project is paramount, and this is achieved through rigorous quality control measures and a comprehensive compliance framework. The project includes several departments dedicated to ensuring that all research activities comply with ethical guidelines and regulatory standards. The risk management department plays a crucial role in identifying and mitigating potential risks that could compromise the integrity of the study. This department works closely with the internal audit and ethics compliance teams to ensure that all research activities adhere to ethical standards, such as the Helsinki Declaration and national regulations for the protection of personal data. The quality control teams are responsible for monitoring the quality of the biological samples and ensuring that all data is accurate and reliable. These teams perform regular audits and implement corrective and preventive actions (CAPA) when necessary to address any issues that arise during the course of the study. The documentation and archiving department is responsible for managing all project records, including audit reports, data transfer logs, and compliance records. This department ensures that all project-related documentation is securely stored and readily accessible for review, facilitating transparency and accountability. The project also includes a procurement and supply chain management team, which is responsible for ensuring that all necessary materials, equipment, and reagents are procured in a timely manner. This team manages the logistics of material transfers and ensures that all supplies meet the required quality standards. Ethical Considerations and Participant Safety The safety and privacy of participants are paramount in the conduct of the study. All participant data is anonymized and stored securely to protect their confidentiality. The project adheres to both national and international regulations regarding the protection of personal data, ensuring that participants' rights are respected at all times. Informed consent is obtained from all participants before they are enrolled in the study. Participants are provided with detailed information about the study's objectives, procedures, and potential risks. They are also informed of their right to withdraw from the study at any time without penalty. The study has received ethical approval from the relevant national ethics committees, ensuring that all research activities comply with established ethical guidelines. Regular audits are conducted to ensure that all procedures are followed correctly and that any ethical concerns are addressed promptly. Data Integration and Visualization Upon completion of the study, all data from the genomic, epigenomic, and transcriptomic analyses will be integrated and visualized using state-of-the-art bioinformatics tools. The integrated dataset will provide a comprehensive view of the molecular mechanisms underlying ASD, allowing researchers to identify key biomarkers and potential therapeutic targets. The integrated data will be presented through various visualization techniques, such as heatmaps, network maps, and pathway diagrams. These visualizations will help researchers interpret the data and draw meaningful conclusions about the biological processes involved in ASD. Conclusion This project is a landmark study in the field of ASD research, utilizing a multi-omics approach to uncover the genetic, epigenetic, and environmental factors contributing to the disorder. The project's multi-disciplinary structure, with dedicated teams for clinical operations, data analysis, quality control, and compliance, ensures that the research is conducted with the highest level of scientific rigor. By integrating genomic, epigenomic, and transcriptomic data, the project aims to provide new insights into the molecular mechanisms underlying ASD and to identify potential biomarkers for diagnosis and treatment. The findings from this study could pave the way for personalized medicine approaches to ASD, improving the quality of life for individuals affected by the disorder.