Article

Prenatal and perinatal risk factors for autism - A review and integration of findings

Department of Epidemiology, Columbia University, New York, New York, United States
Archives of Pediatrics and Adolescent Medicine (Impact Factor: 5.73). 04/2007; 161(4):326-33. DOI: 10.1001/archpedi.161.4.326
Source: PubMed

ABSTRACT

To review the evidence for the presence of prenatal and perinatal factors that affect the risk of autism and autism spectrum disorders.
Relevant articles were identified by searching MEDLINE, screening reference lists of original studies, and searching major journals likely to publish epidemiological studies on the topic.
For inclusion in this review, studies required (1) a well-defined sample of cases drawn from population-based registers or cohorts; (2) standardized, prospectively collected obstetric information from birth records or registers; (3) comparison subjects drawn from the general population with information on obstetric complications collected from the same source; and (4) a standardized format for presentation of data, allowing for comparisons among studies. Main Exposures Parental characteristics and obstetric complications.
Rates of autism and autism spectrum disorders.
Seven epidemiological studies were identified that fulfilled inclusion criteria. The parental characteristics associated with an increased risk of autism and autism spectrum disorders included advanced maternal age, advanced paternal age, and maternal place of birth outside Europe or North America. The obstetric conditions that emerged as significant fell into 2 categories: (1) birth weight and duration of gestation and (2) intrapartum hypoxia.
Evidence to suggest that parental age and obstetric conditions are associated with an increased risk of autism and autism spectrum disorders is accumulating. Although not proven as independent risk factors for autism, these variables should be examined in future studies that use large, population-based birth cohorts with precise assessments of exposures and potential confounders.

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    • "Hence, in many cases, autism is considered to be multifactorial, and other factors besides the mere genetic variation must play a role. Factors currently being studied include epigenetic modifications, perinatal problems (Kolevzon et al., 2007), intra-uterine testosterone levels (Auyeung et al., 2009; Baron-Cohen et al., 2015), immune dysfunction (Goines and Van de Water, 2010), pesticides (Roberts et al., 2007), in utero exposure to medication (Bromley et al., 2013; Rai et al., 2013), alterations to the gut microbiome (Mayer et al., 2014), and many others as reviewed by Herbert (Herbert, 2010). "
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    ABSTRACT: Background: Given the wide variety of the phenotype, the uncertain genetic origins and the discussions surrounding the status of autism itself, genetic research on autism genes generates specific ethical questions that are not completely analogous to the ethical issues of genetic research in general. Method: In order to map ethical issues surrounding research on autism genes, as experienced by professionals in the field of autism, we interviewed 15 Belgian professionals. Results: We found that respondents believed that the heterogeneity of the autism phenotype affects the ethics of research on several levels. It affects issues regarding who to include in research on autism genes, regarding what the aim is of such studies, and how the research is done. Conclusions: Although genetic research on autism genes is proliferating, a systematic ethical reflection and protocol is missing. With this study we have shown that autism professionals in Belgium express both skepticism and hope with regard to genetic research and raise important points with regard to the effect that the complexity of autism has on research aims and methodology.
    No preview · Article · Dec 2015 · European journal of medical genetics
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    • "Despite its serious social impact[4], the causes of autism are poorly understood, but both genetic (10–20 %) and environmental factors are thought to be involved. Researchers have noted several risk factors related to ASD including advanced maternal and/or paternal age, maternal smoking history, low birth weight, short gestational duration, and hypoxia during childbirth[5]. In addition, environmental factors, including constituents of air pollution, have been found to be related to an increased risk of autism[6,7]. "
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    ABSTRACT: Background: Autism spectrum disorders (ASD) constitute a major public health problem affecting one in 68 children. There is little understanding of the causes of ASD despite its serious social impact. Air pollution contains many toxicants known to have adverse effects on the fetus. We conducted a population based case-control study in southwestern Pennsylvania to estimate the association between ASD and 2005 US EPA modeled NATA (National Air Toxics Assessment) levels for 30 neurotoxicants. Methods: A total of 217 ASD cases born between 2005 and 2009 were recruited from local ASD diagnostic and treatment centers. There were two different control groups: 1) interviewed controls (N = 224) frequency matched by child's year of birth, sex and race with complete residential histories from prior to pregnancy through the child's second birthday, and 2) 5,007 controls generated from a random sample of birth certificates (BC controls) using residence at birth. We used logistic regression analysis comparing higher to first quartile of exposure to estimate odds ratios (ORs) and 95 % confidence intervals (CI), adjusting for mother's age, education, race, smoking status, child's year of birth and sex. Results: Comparing fourth to first quartile exposures for all births, the adjusted OR for styrene was 2.04 (95 % CI = 1.17-3.58, p = 0.013) for the interviewed case-control analysis and 1.61 (95 % CI = 1.08-2.40, p = 0.018) for the BC analysis. In the BC comparison, chromium also exhibited an elevated OR of 1.60 (95 % CI = 1.08-2.38, p = 0.020), which was similarly elevated in the interviewed analysis (OR = 1.52, 95 % CI = 0.87-2.66). There were borderline significant ORs for the BC comparison for methylene chloride (OR = 1.41, 95 % CI = 0.96-2.07, p = 0.082) and PAHs (OR = 1.44, 95 % CI = 0.98-2.11, p = 0.064). Conclusions: Living in areas with higher levels of styrene and chromium during pregnancy was associated with increased risk of ASD, with borderline effects for PAHs and methylene chloride. These results are consistent with other studies. It is unclear, however, whether these chemicals are risk factors themselves or if they reflect the effect of a mixture of pollutants. Future work should include improved spatiotemporal estimates of exposure to air toxics, taking into account the dynamic movement of individuals during daily life.
    Full-text · Article · Oct 2015 · Environmental Health
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    • "Autism spectrum disorder (ASD) comprise a group of chronic neurodevelopmental disorders characterized by social and language impairments and restricted and repetitive interests and behaviors[1]. ASD includes autistic disorder, Asperger's syndrome, and pervasive developmental disorder not otherwise specified (PDD-NOS)[2]. Patients with ASD vary greatly in terms of clinical manifestation and may also show associated medical comorbidities. "
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    ABSTRACT: Autism spectrum disorder (ASD) comprise a group of neurodevelopmental disorders characterized by deficits in social and communication capacities and repetitive behaviors. Increasing neuroscientific evidence indicates that the neuropathology of ASD is widespread and involves epigenetic regulation in the brain. Differentially expressed miRNAs in the peripheral blood from autism patients were identified by high-throughput miRNA microarray analyses. Five of these miRNAs were confirmed through quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis. A search for candidate target genes of the five confirmed miRNAs was performed through a Kyoto encyclopedia of genes and genomes (KEGG) biological pathways and Gene Ontology enrichment analysis of gene function to identify gene regulatory networks. To the best of our knowledge, this study provides the first global miRNA expression profile of ASD in China. The differentially expressed miR-34b may potentially explain the higher percentage of male ASD patients, and the aberrantly expressed miR-103a-3p may contribute to the abnormal ubiquitin-mediated proteolysis observed in ASD.
    Full-text · Article · Jun 2015 · PLoS ONE
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