Prevalence and characteristics of autism spectrum disorders in the ALSPAC cohort

Developmental Medicine & Child Neurology (Impact Factor: 3.51). 08/2008; 50(9):672 - 677. DOI: 10.1111/j.1469-8749.2008.03042.x


The aim of this study was to determine the prevalence of autistic spectrum disorder (ASD) within a large representative population sample: the Avon Longitudinal Study of Parents and Children (ALSPAC). Cases of ASD were identified from the clinical notes of children in the ALSPAC with a suspected developmental disorder and from the Pupil Level Annual Schools Census (PLASC) for England in 2003. Seventy-one cases of ASD diagnosed after a multidisciplinary assessment were identified from health records. There were an additional 15 cases from PLASC data in which ASD was mentioned as a principal difficulty, thus giving a total of 86 children diagnosed by the age of 11 years. Prevalence of ASD per 10 000 population at 11 years was 51.1 for those with a multi-professional diagnosis, and 61.9 if cases from education were included, made up of 21.6 for childhood autism, 10.8 for atypical autism, 16.6 for Asperger syndrome, and 13.0 for unspecified ASD. The male:female ratio was 6.8:1. Median age at diagnosis ranged from 45 months in childhood autism to 116 months in Asperger syndrome. A comorbid developmental disorder was recorded in 33.8% of cases, including learning disability† in 14.7%, epilepsy in 10.3%, and mixed developmental disorder in 4.4%. We conclude that the prevalence of ASD diagnosed at 11 years in a UK representative population-based sample is at least 51.1/10 000.

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    • "diagnostic methods or any of these in combination. In most ASD diagnoses, a skewed gender ratio has been found, with increased prevalence in males at a ratio of 4:1 (males:females) or even higher (Scott et al., 2002; Williams et al., 2008). One hypothesis that takes into account the gender effect and the cognitive style of ASD is the 'extreme male brain theory'. "
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    ABSTRACT: Autism spectrum disorders (ASD) are a heterogeneous group of disorders which have complex behavioural phenotypes. Although ASD is a highly heritable neuropsychiatric disorder, genetic research alone has not provided a profound understanding of the underlying causes. Recent developments using biochemical tools such as transcriptomics, proteomics and cellular models, will pave the way to gain new insights into the underlying pathological pathways. This review addresses the state-of-the-art in the search for molecular biomarkers for ASD. In particular, the most important findings in the biochemical field are highlighted and the need for establishing streamlined interaction between behavioural studies, genetics and proteomics is stressed. Eventually, these approaches will lead to suitable translational ASD models and, therefore, a better disease understanding which may facilitate novel drug discovery efforts in this challenging field.
    The International Journal of Neuropsychopharmacology 11/2013; 17(04):1-23. DOI:10.1017/S146114571300117X · 4.01 Impact Factor
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    • "Within ALSPAC there is a very small proportion of children with ASD, who were either identified from community paediatric records (National Health Service) or from Education Service databases for the region [36]. Specifically, there were 86 children with ASD at the age of 11 years (prevalence: 62 per 10,000 children). "
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    ABSTRACT: Social communication difficulties represent an autistic trait that is highly heritable and persistent during the course of development. However, little is known about the underlying genetic architecture of this phenotype. We performed a genome-wide association study on parent-reported social communication problems using items of the children's communication checklist (age 10 to 11 years) studying single and/or joint marker effects. Analyses were conducted in a large UK population-based birth cohort (Avon Longitudinal Study of Parents and their Children, ALSPAC, N = 5,584) and followed-up within a sample of children with comparable measures from Western Australia (RAINE, N = 1364). Two of our seven independent top signals (P-discovery <1.0E-05) were replicated (0.009 < P-replication <=0.02) within RAINE and suggested evidence for association at 6p22.1 (rs9257616, meta-P = 2.5E-07) and 14q22.1 (rs2352908, meta-P = 1.1E-06). The signal at 6p22.1 was identified within the olfactory receptor gene cluster within the broader major histocompatibility complex (MHC) region. The strongest candidate locus within this genomic area was TRIM27. This gene encodes an ubiquitin E3 ligase, which is an interaction partner of methyl-CpG-binding domain (MBD) proteins, such as MBD3 and MBD4, and rare protein-coding mutations within MBD3 and MBD4 have been linked to autism. The signal at 14q22.1 was found within a gene-poor region.Single-variant findings were complemented by estimations of the narrow-sense heritability in ALSPAC suggesting that approximately a fifth of the phenotypic variance in social communication traits is accounted for by joint additive effects of genotyped single nucleotide polymorphisms throughout the genome (h2(SE) = 0.18(0.066), P = 0.0027). Overall, our study provides both joint and single-SNP-based evidence for the contribution of common polymorphisms to variation in social communication phenotypes.
    Molecular Autism 09/2013; 4(1):34. DOI:10.1186/2040-2392-4-34 · 5.41 Impact Factor
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    • "Our results are also similar to the 1.2% and 0.9% prevalence estimates, reported by large UK and US studies, respectively, using active screening and diagnostic evaluations (through clinical assessment or case-note review) in populations with identified special education needs, symptoms associated with ASD or co-morbid conditions [4], [5]. A lower prevalence (0.6%) was, however, reported from another UK study of comparable design [32]. Studies like these may overlook affected children in the general population who, due to various barriers to care, remain unidentified [5], [32]. "
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    ABSTRACT: Reports of rising prevalence of autism spectrum disorders (ASD), along with their profound personal and societal burden, emphasize the need of methodologically sound studies to explore their causes and consequences. We here present the design of a large intergenerational resource for ASD research, along with population-based prevalence estimates of ASD and their diagnostic validity. The Stockholm Youth Cohort is a record-linkage study comprising all individuals aged 0-17 years, ever resident in Stockholm County in 2001-2007 (N = 589,114). ASD cases (N = 5,100) were identified using a multisource approach, involving registers covering all pathways to ASD diagnosis and care, and categorized according to co-morbid intellectual disability. Prospectively recorded information on potential determinants and consequences of ASD were retrieved from national and regional health and administrative registers. Case ascertainment was validated through case-note review, and cross validation with co-existing cases in a national twin study. The 2007 year prevalence of ASD in all children and young people was 11.5 per 1,000 (95% confidence interval 11.2-11.8), with a co-morbid intellectual disability recorded in 42.6% (41.0-44.2) of cases. We found 96.0% (92.0-98.4) of reviewed case-notes being consistent with a diagnosis of ASD, and confirmed ASD in 85.2% (66.2-95.8) of affected twins. Findings from this contemporary study accords with recently reported prevalence estimates from Western countries at around 1%, based on valid case ascertainment. The Stockholm Youth Cohort, in light of the availability of extensive information from Sweden's registers, constitutes an important resource for ASD research. On-going work, including collection of biological samples, will enrich the study further.
    PLoS ONE 07/2012; 7(7):e41280. DOI:10.1371/journal.pone.0041280 · 3.23 Impact Factor
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