Autism Spectrum Disorders (ASD) Prevalence Map

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Map comes from this report on Experimental Models to Study Autism Spectrum Disorders: hiPSCs, Rodents and ZebrafishThe map above shows the the prevalence of Autism Spectrum Disorders (ASD) around the world in 2017. Light green: prevalence between 0–0.4%; blue: prevalence between 0.4–0.6%; green: prevalence between 0.6–0.8%; dark green: prevalence between 0.8–1%.Countries from which no data are available are plotted in grey. The figure was elaborated using R software (R Core Team, Vienna, Austria) to represent open access data which have been previously standardized to age and sex.It comes report entitled: Experimental Models to Study Autism Spectrum Disorders: hiPSCs, Rodents and Zebrafish by Alba Pensado-López, Sara Veiga-Rúa, Ángel Carracedo, Catarina Allegue and Laura Sánchez.Here’s a brief summary of it, but you can read the whole thing for free online here.The report reviews current experimental models used to study Autism Spectrum Disorders (ASD). ASD affects approximately 1.5% of the global population and is characterized by deficits in social communication, repetitive behaviors, and restricted interests.The review highlights the complex interplay of genetic and environmental factors in ASD etiology and underscores the need for diverse models to explore disease mechanisms and potential therapies.Epidemiology and EtiologyASD is a neurodevelopmental disorder with both genetic and environmental risk factors. The report discusses:Variability in prevalence data due to diagnostic challenges and regional differences.The contribution of prenatal, perinatal, and postnatal risk factors including advanced parental age, birth complications, vitamin D deficiency, and exposure to heavy metals.The genetic basis of ASD, including findings from twin studies and genome-wide association studies (GWAS), which have identified both common and rare genetic variants and numerous ASD-associated genes (e.g., those cataloged in the SFARI Gene Database).Genome Editing SystemsA major section of the report is dedicated to genome editing tools that have revolutionized the study of ASD:Zinc Finger Nucleases (ZFNs) – the first generation of gene editing tools.TALENs – offering easier synthesis compared to ZFNs.CRISPR/Cas Systems – noted for simplicity, versatility, and efficiency, which have enabled targeted editing, regulation of gene expression, and the creation of pre-clinical models in various organisms.In Vitro Models: hiPSCsThe report describes the breakthrough in reprogramming adult somatic cells into human induced pluripotent stem cells (hiPSCs). These cells can be differentiated into neural cell types, providing a patient-specific in vitro model to:Investigate the molecular and cellular mechanisms underlying ASD.Establish genotype–phenotype correlations by comparing cells derived from patients with those from controls.Test new therapeutic approaches, including drug screenings and cell-based interventions.Animal ModelsRodentsRodents (mice and rats) have been widely used in ASD research due to their:Genetic and neuroanatomical similarities to humans.Availability of diverse behavioral assays to evaluate social interactions, repetitive behaviors, and communication deficits.Utility in both forward and reverse genetic approaches, including the generation of knockout models for key ASD-associated genes.ZebrafishZebrafish are emerging as a valuable model in ASD research because of:Their rapid development, optical transparency, and cost-effectiveness for high-throughput screening.Genetic conservation with humans – about 70% of human genes have zebrafish orthologues.Adaptability to genome editing techniques (e.g., CRISPR/Cas9), allowing the generation of stable mutants to study neurodevelopmental processes and behavior.ConclusionsThe report concludes that a combination of in vitro (hiPSC-based) and in vivo (rodent and zebrafish) models is essential for unravelling the complex genetic and environmental underpinnings of ASD.These models not only help in understanding disease mechanisms but also provide platforms for testing potential therapeutic interventions.Why is autism more common in some parts of the world compared to others?Differences in reported autism prevalence around the world can stem from several factors:1. Diagnostic Practices and AwarenessIn some regions, higher awareness among healthcare providers and the public leads to earlier and more accurate diagnoses. Variability in diagnostic criteria and access to specialized services can result in underdiagnosis in areas with fewer resources.2. Methodological DifferencesStudies across countries often use different methods for data collection and analysis. Some regions may have more robust reporting systems, while others face challenges in gathering reliable data, leading to discrepancies in prevalence figures.3. Environmental and Socioeconomic FactorsFactors such as parental age, pregnancy and birth complications, vitamin D levels, and exposure to environmental toxins can vary by region. These differences might contribute to real variations in autism risk.4. Genetic BackgroundGenetic predispositions can differ among populations. Regional genetic variations, possibly interacting with local environmental factors, may also influence the prevalence of autism.In summary, both actual differences in risk factors and variations in how autism is diagnosed and reported contribute to the differences in prevalence across the globe.What do you think?