Gene- Environment Intereactions in Austim Spectrum Disorders ASD

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Publication . Vilela, Joana; Martiniano, Hugo; Marques, Ana Rita; Santos, João Xavier; Rasga, Célia; Oliveira, Guiomar; Vicente, Astrid Moura

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder with heterogeneous clinical presentation, variable severity, and multiple comorbidities. A complex underlying genetic architecture matches the clinical heterogeneity, and evidence indicates that several co-occurring brain disorders share a genetic component with ASD. In this study, we established a genetic similarity disease network approach to explore the shared genetics between ASD and frequent comorbid brain diseases (and subtypes), namely Intellectual Disability, Attention-Deficit/Hyperactivity Disorder, and Epilepsy, as well as other rarely co-occurring neuropsychiatric conditions in the Schizophrenia and Bipolar Disease spectrum. Using sets of disease-associated genes curated by the DisGeNET database, disease genetic similarity was estimated from the Jaccard coefficient between disease pairs, and the Leiden detection algorithm was used to identify network disease communities and define shared biological pathways. We identified a heterogeneous brain disease community that is genetically more similar to ASD, and that includes Epilepsy, Bipolar Disorder, Attention-Deficit/Hyperactivity Disorder combined type, and some disorders in the Schizophrenia Spectrum. To identify loss-of-function rare de novo variants within shared genes underlying the disease communities, we analyzed a large ASD whole-genome sequencing dataset, showing that ASD shares genes with multiple brain disorders from other, less genetically similar, communities. Some genes (e.g., SHANK3, ASH1L, SCN2A, CHD2, and MECP2) were previously implicated in ASD and these disorders. This approach enabled further clarification of genetic sharing between ASD and brain disorders, with a finer granularity in disease classification and multi-level evidence from DisGeNET. Understanding genetic sharing across disorders has important implications for disease nosology, pathophysiology, and personalized treatment.

2022-08-18Journal article

Open access

Evidence for an association of prenatal exposure to particulate matter with clinical severity of Autism Spectrum Disorder

Publication . Santos, João Xavier; Sampaio, Pedro; Rasga, Célia; Martiniano, Hugo; Faria, Clarissa; Café, Cátia; Oliveira, Alexandra; Duque, Frederico; Oliveira, Guiomar; Sousa, Lisete; Nunes, Ana; Moura Vicente, Astrid

Early-life exposure to air pollutants, including ozone (O3), particulate matter (PM2.5 or PM10, depending on diameter of particles), nitrogen dioxide (NO2) and sulfur dioxide (SO2) has been suggested to contribute to the etiology of Autism Spectrum Disorder (ASD). In this study, we used air quality monitoring data to examine whether mothers of children with ASD were exposed to high levels of air pollutants during critical periods of pregnancy, and if higher exposure levels may lead to a higher clinical severity in their offspring. We used public data from the Portuguese Environment Agency to estimate exposure to these pollutants during the first, second and third trimesters of pregnancy, full pregnancy and first year of life of the child, for 217 subjects with ASD born between 2003 and 2016. These subjects were stratified in two subgroups according to clinical severity, as defined by the Autism Diagnostic Observational Schedule (ADOS). For all time periods, the average levels of PM2.5, PM10 and NO2 to which the subjects were exposed were within the admissible levels defined by the European Union. However, a fraction of these subjects showed exposure to levels of PM2.5 and PM10 above the admissible threshold. A higher clinical severity was associated with higher exposure to PM2.5 (p = 0.001), NO2 (p = 0.011) and PM10 (p = 0.041) during the first trimester of pregnancy, when compared with milder clinical severity. After logistic regression, associations with higher clinical severity were identified for PM2.5 exposure during the first trimester (p = 0.002; OR = 1.14, 95%CI: 1.05–1.23) and full pregnancy (p = 0.04; OR = 1.07, 95%CI: 1.00–1.15) and for PM10 (p = 0.02; OR = 1.07, 95%CI: 1.01–1.14) exposure during the third trimester. Exposure to PM is known to elicit neuropathological mechanisms associated with ASD, including neuroinflammation, mitochondrial disruptions, oxidative stress and epigenetic changes. These results offer new insights on the impact of earlylife exposure to PM in ASD clinical severity.

2023-04-05Journal article

Open access

Gene-environment interactions in Autism Spectrum Disorder (ASD)

Publication . Santos, João Xavier; Vicente, Astrid Moura; Nunes, Ana

Autism Spectrum Disorder (ASD) is a heterogeneous neurodevelopmental disorder characterized by deficits in social communication and interaction and repetitive and restricted behaviors. While heritability estimates support a role for gene-environment interactions in ASD etiology, there is a paucity of strategies that integrate both components. The objective of this work was to identify gene-environment interactions involved in ASD risk. Through a systematic literature review we identified neurotoxic xenobiotics previously implicated in ASD, including air pollutants and endocrine disruptors. Using a school-based screening strategy we provide an updated prevalence estimate for 7-9 years old children from Centro Region of Portugal, of 0.5% (95% CI: 0.3-0.7). Leveraging public air quality monitoring data we estimated early-life exposure to criteria air pollutants in 217 ASD-subjects, and show that exposure to particulate matter during critical neurodevelopmental windows is associated with a higher clinical severity of ASD. In silico inspection of large genetic datasets (N=6224) showed that ASD-subjects carry predicted-damaging variants in a panel of 77 genes involved in the regulation of detoxification and physiological barriers (blood-brain barrier and placenta) permeability (XenoReg genes). Database query indicates that these genes interact with ASD implicated xenobiotics. Through biochemical analyses of neonatal dried blood spots and the piloting of an early-life exposures assessment questionnaire we retrospectively collected environmental data for 70 ASD-children. The integration of environmental and sequencing data revealed a group of 13 patients for whom gene-environment interactions likely contributed to disease etiology. We present evidence that genetically-susceptible subjects might be at higher risk of ASD due to an increased vulnerability to early-life exposures. Possible underlying neuropathological mechanisms, including neuroinflammation, oxidative stress, endocrine disruption and epigenetics, warrant experimental validation. This work reinforces the need for clinical stratification and for monitoring early-life exposures, providing knowledge that, prospectively, may be translated to personalized medicine strategies applied in clinical practice.

2023-01-26Doctoral thesis

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Gene Variants Involved in Nonsense-Mediated mRNA Decay Suggest a Role in Autism Spectrum Disorder

Publication . Marques, Ana Rita; Santos, João Xavier; Martiniano, Hugo; Vilela, Joana; Rasga, Célia; Romão, Luísa; Vicente, Astrid Moura

Autism Spectrum Disorder (ASD) is a heterogeneous neurodevelopmental condition with unclear etiology. Many genes have been associated with ASD risk, but the underlying mechanisms are still poorly understood. An important post-transcriptional regulatory mechanism that plays an essential role during neurodevelopment, the Nonsense-Mediated mRNA Decay (NMD) pathway, may contribute to ASD risk. In this study, we gathered a list of 46 NMD factors and regulators and investigated the role of genetic variants in these genes in ASD. By conducting a comprehensive search for Single Nucleotide Variants (SNVs) in NMD genes using Whole Exome Sequencing data from 1828 ASD patients, we identified 270 SNVs predicted to be damaging in 28.7% of the population. We also analyzed Copy Number Variants (CNVs) from two cohorts of ASD patients (N = 3570) and discovered 38 CNVs in 1% of cases. Importantly, we discovered 136 genetic variants (125 SNVs and 11 CNVs) in 258 ASD patients that were located within protein domains required for NMD. These gene variants are classified as damaging using in silico prediction tools, and therefore may interfere with proper NMD function in ASD. The discovery of NMD genes as candidates for ASD in large patient genomic datasets provides evidence supporting the involvement of the NMD pathway in ASD pathophysiology.

2022-03-13Journal article

Open access