[Show abstract][Hide abstract] ABSTRACT: We have undertaken a genome-wide analysis of rare copy-number variation (CNV) in 1124 autism spectrum disorder (ASD) families, each comprised of a single proband, unaffected parents, and, in most kindreds, an unaffected sibling. We find significant association of ASD with de novo duplications of 7q11.23, where the reciprocal deletion causes Williams-Beuren syndrome, characterized by a highly social personality. We identify rare recurrent de novo CNVs at five additional regions, including 16p13.2 (encompassing genes USP7 and C16orf72) and Cadherin 13, and implement a rigorous approach to evaluating the statistical significance of these observations. Overall, large de novo CNVs, particularly those encompassing multiple genes, confer substantial risks (OR = 5.6; CI = 2.6-12.0, p = 2.4 × 10(-7)). We estimate there are 130-234 ASD-related CNV regions in the human genome and present compelling evidence, based on cumulative data, for association of rare de novo events at 7q11.23, 15q11.2-13.1, 16p11.2, and Neurexin 1.
[Show abstract][Hide abstract] ABSTRACT: Siblings of probands with autism spectrum disorders are at higher risk for developing the broad autism phenotype (BAP). We compared the linguistic abilities (i.e., pragmatic language, school achievements, and underling reading processes) of 35 school-age siblings of children with autism (SIBS-A) to those of 42 siblings of children with typical development. Results indicated lower pragmatic abilities in a subgroup of SIBS-A identified with BAP related difficulties (SIBS-A-BAP) whereas school achievements and reading processes were intact. Furthermore, among SIBS-A-BAP, significant negative correlations emerged between the severity scores on the Autism Diagnostic Observation Schedule and full and verbal IQ scores. These results are discussed in the context of the developmental trajectories of SIBS-A and in relation to the BAP.
Journal of Autism and Developmental Disorders 06/2011; 41(6):750-60. DOI:10.1007/s10803-010-1096-6 · 3.06 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Standardized calibrated severity scores (CSS) have been created for Autism Diagnostic Observation Schedule, 2nd edition (ADOS-2) Modules 1-4 as a metric of the relative severity of autism-specific behaviors. Total and domain CSS were created for the Toddler Module to facilitate comparison to other modules. Analyses included 388 children with ASD age 12-30 months and were replicated on 435 repeated assessments from 127 children with ASD. Compared to raw scores, associations between total and domain CSS and participant characteristics were reduced in the original sample. Verbal IQ effects on Social Affect-CSS were not reduced in the replication sample. Toddler Module CSS increases comparability of ADOS-2 scores across modules and allows studies of symptom trajectories to extend to earlier ages.
International Meeting for Autism Research 2011; 05/2011
[Show abstract][Hide abstract] ABSTRACT: Autism Diagnostic Interview-Revised (Rutter et al. in Autism diagnostic interview-revised. Western Psychological Services, Los Angeles, 2003) diagnostic algorithms specific to toddlers and young preschoolers were created using 829 assessments of children aged from 12 to 47 months with ASD, nonspectrum disorders, and typical development. The participants were divided into three more homogeneous groups by language level and age. Items that best differentiated the diagnostic groups were selected and arranged into domains based on multifactor item-response analyses. Using the new algorithms for toddlers and preschool children, we were able to improve sensitivity and specificity compared to the previously developed algorithm.
Journal of Autism and Developmental Disorders 03/2011; 42(1):82-93. DOI:10.1007/s10803-011-1213-1 · 3.06 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Delays in development are a fundamental feature in diagnosing autism spectrum disorders (ASD). Age of language acquisition, usually obtained through retrospective caregiver report, is currently used to distinguish between categories within ASD. Research has shown that caregivers often report children as having acquired developmental milestones earlier or later than they were actually achieved. The current study examines the extent to which this phenomenon, referred to as 'telescoping,' impacts retrospective reports provided by caregivers of children with ASD.
Participants were 127 caregivers of children referred for possible ASD or non-spectrum developmental delay. Caregivers were interviewed when children were 2, 3, 5, and 9 years of age. Caregiver-reported ages of first concern, language and non-diagnostic developmental milestones and interviewer-estimated age of onset were compared over time using linear models.
Significant telescoping of language milestones resulted in more children meeting language delay criteria as they grew older, in spite of original reports that their language was not delayed. There was little evidence of consistent telescoping of caregiver-reported ages of first concern, daytime bladder control, and independent walking. With time, the interviewers' judged ages of symptom onset increased, but remained prior to age three.
Telescoping of caregiver-reported ages of language acquisition has implications for both clinical diagnosis and genetic studies using these milestones to increase homogeneity of samples. Results support proposals to remove specific age-based criteria in the diagnosis of ASD. Telescoping should be considered when working with any clinical population in which retrospectively recalled events are used in diagnosis.
Journal of Child Psychology and Psychiatry 03/2011; 52(7):753-60. DOI:10.1111/j.1469-7610.2011.02398.x · 6.46 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The study's objectives were to assess diagnostic stability of initial autism spectrum disorder (ASD) diagnoses in community settings and identify factors associated with diagnostic instability using data from a national Web-based autism registry. A Cox proportional hazards model was used to assess the relative risk of change in initial ASD diagnosis as a function of demographic characteristics, diagnostic subtype, environmental factors and natural history. Autistic disorder was the most stable initial diagnosis; pervasive developmental disorder-not otherwise specified was the least stable. Additional factors such as diagnosing clinician, region, when in time a child was initially diagnosed, and history of autistic regression also were significantly associated with diagnostic stability in community settings. Findings suggest that the present classification system and other secular factors may be contributing to increasing instability of community-assigned labels of ASD.
Journal of Autism and Developmental Disorders 01/2011; 41(1):110-21. DOI:10.1007/s10803-010-1031-x · 3.06 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Models of autism spectrum disorders (ASD) as neural disconnection syndromes have been predominantly supported by examinations of abnormalities in corticocortical networks in adults with autism. A broader body of research implicates subcortical structures, particularly the striatum, in the physiopathology of autism. Resting state functional magnetic resonance imaging has revealed detailed maps of striatal circuitry in healthy and psychiatric populations and vividly captured maturational changes in striatal circuitry during typical development.
Using resting state functional magnetic resonance imaging, we examined striatal functional connectivity (FC) in 20 children with ASD and 20 typically developing children between the ages of 7.6 and 13.5 years. Whole-brain voxelwise statistical maps quantified within-group striatal FC and between-group differences for three caudate and three putamen seeds for each hemisphere.
Children with ASD mostly exhibited prominent patterns of ectopic striatal FC (i.e., functional connectivity present in ASD but not in typically developing children), with increased functional connectivity between nearly all striatal subregions and heteromodal associative and limbic cortex previously implicated in the physiopathology of ASD (e.g., insular and right superior temporal gyrus). Additionally, we found striatal functional hyperconnectivity with the pons, thus expanding the scope of functional alterations implicated in ASD. Secondary analyses revealed ASD-related hyperconnectivity between the pons and insula cortex.
Examination of FC of striatal networks in children with ASD revealed abnormalities in circuits involving early developing areas, such as the brainstem and insula, with a pattern of increased FC in ectopic circuits that likely reflects developmental derangement rather than immaturity of functional circuits.
[Show abstract][Hide abstract] ABSTRACT: With the ongoing consideration of the diagnostic criteria for mental disorders that is active in the Diagnostic and Statistical Manual of Mental Disorders (DSM-V) and International Classification of Diseases (ICD-11) revision processes, it is timely to review the phenomenological overlap between autism and schizophrenia. These disorders have at various times been regarded alternatively as closely related and as non-overlapping and incompatible. Nevertheless, there are several reports in the literature that have described individuals with both autism and schizophrenia, and the broader phenotypes of these disorders clearly intersect. Recent studies reveal theory of mind deficits in both disorders, and mirror neuron impairments also appear to be shared. There also may be similar connectivity deficits emerging in functional imaging studies, and both disorders share several genetic signals that are being identified through detection of copy number variants. Taken together, these data suggest that it may be time to revisit the possibility that these disorders are related.
Brain research 11/2010; 1380:34-41. DOI:10.1016/j.brainres.2010.11.031 · 2.84 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Autism is the most commonly studied of a spectrum of developmental disorders that are believed to be neurobiologically based but which, at this point, for lack of good biomarkers, are defined purely by behavior. In the last 20 years, the definition of autism has shifted in emphasis from extreme aloofness and positive signs of abnormality in repetitive and sensorimotor behaviors to a greater awareness of the importance of more subtle reciprocal social communication deficits as core features. Standard diagnostic instruments were developed for research purposes to acquire information both through caregiver interviews and direct clinical observation. Use of these instruments in clinical practice resulted in major improvements, which in turn affected research results. These results yielded further improvements that led to changes in clinical practice over time. The synergism between research and clinical practice in the understanding of autism is discussed.
American Psychologist 11/2010; 65(8):815-26. DOI:10.1037/0003-066X.65.8.815 · 6.87 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Glutamate transporters are critical for signaling and excitotoxicity because they regulate extracellular glutamate in the synapse. Four glutamate transporter genes, SLC1A1, SLC1A2, SLC1A3, and SLC1A6, are positional and functional candidates for autism. Studies have implicated SLC1A1 in obsessive-compulsive disorder (Arnold et al., 2006) and autism spectrum disorder (ASD) (Brune et al., 2008). Upregulation of SLC1A2 and SLC1A3 has been reported in brains of individuals with autism (Purcell et al., 2001). SLC1A2 is under the highest linkage peak in the Autism Genome Project scan (Szatmari et al., 2007). Both SLC1A3 and SLC1A6 are most abundantly expressed in cerebellum (Bridges and Esslinger, 2005) where structural and functional deficits occur in autism. On the basis of these lines of evidence, we hypothesized that variations in these four glutamate transporter genes confer risk for autism susceptibility.
[Show abstract][Hide abstract] ABSTRACT: We examined to what extent increased parent reports of autistic traits in some children with Attention Deficit Hyperactivity Disorder (ADHD) are the result of ADHD-related symptoms or qualitatively similar to the core characteristics of autism spectrum disorders (ASD). Results confirm the presence of a subgroup of children with ADHD and elevated ratings of core ASD traits (ADHD(+)) not accounted for by ADHD or behavioral symptoms. Further, analyses revealed greater oppositional behaviors, but not greater ADHD severity or anxiety, in the ADHD(+) subgroup compared to those with ADHD only. These results highlight the importance of specifically examining autistic traits in children with ADHD for better characterization in studies of the underlying physiopathology and treatment.
Journal of Autism and Developmental Disorders 11/2010; 41(9):1178-91. DOI:10.1007/s10803-010-1135-3 · 3.06 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Although autism spectrum disorders (ASDs) have a substantial genetic basis, most of the known genetic risk has been traced to rare variants, principally copy number variants (CNVs). To identify common risk variation, the Autism Genome Project (AGP) Consortium genotyped 1558 rigorously defined ASD families for 1 million single-nucleotide polymorphisms (SNPs) and analyzed these SNP genotypes for association with ASD. In one of four primary association analyses, the association signal for marker rs4141463, located within MACROD2, crossed the genome-wide association significance threshold of P < 5 × 10(-8). When a smaller replication sample was analyzed, the risk allele at rs4141463 was again over-transmitted; yet, consistent with the winner's curse, its effect size in the replication sample was much smaller; and, for the combined samples, the association signal barely fell below the P < 5 × 10(-8) threshold. Exploratory analyses of phenotypic subtypes yielded no significant associations after correction for multiple testing. They did, however, yield strong signals within several genes, KIAA0564, PLD5, POU6F2, ST8SIA2 and TAF1C.
Human Molecular Genetics 10/2010; 19(20):4072-82. DOI:10.1093/hmg/ddq307 · 6.39 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Autism spectrum disorders (ASD) involve a core deficit in social functioning and impairments in the ability to recognize face emotions. In an emotional faces task designed to constrain group differences in attention, the present study used functional MRI to characterize activation in the amygdala, ventral prefrontal cortex (vPFC), and striatum, three structures involved in socio-emotional processing in adolescents with ASD.
Twenty-two adolescents with ASD and 20 healthy adolescents viewed facial expressions (happy, fearful, sad and neutral) that were briefly presented (250 ms) during functional MRI acquisition. To monitor attention, subjects pressed a button to identify the gender of each face.
The ASD group showed greater activation to the faces relative to the control group in the amygdala, vPFC and striatum. Follow-up analyses indicated that the ASD relative to control group showed greater activation in the amygdala, vPFC and striatum (p < .05 small volume corrected), particularly to sad faces. Moreover, in the ASD group, there was a negative correlation between developmental variables (age and pubertal status) and mean activation from the whole bilateral amygdala; younger adolescents showed greater activation than older adolescents. There were no group differences in accuracy or reaction time in the gender identification task.
When group differences in attention to facial expressions were limited, adolescents with ASD showed greater activation in structures involved in socio-emotional processing.
Journal of Child Psychology and Psychiatry 10/2010; 52(3):296-305. DOI:10.1111/j.1469-7610.2010.02317.x · 6.46 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Healthy individuals show robust functional connectivity during rest, which is stronger in adults than in children. Connectivity occurs between the posterior and anterior portions of the default network, a group of structures active in the absence of a task, including the posterior cingulate cortex and the superior frontal gyrus. Previous studies found weaker posterior-anterior connectivity in the default network in adults and adolescents with autism spectrum disorders (ASD). However, these studies used small a priori regions of interest ("seeds") to calculate connectivity. Since seed location for all participants was chosen based on controls' brains, these studies' analyses are more tailored to controls than individuals with ASD. An alternative is to use a data-driven approach, such as self-organizing maps (SOM), to create a reference for each participant to calculate connectivity. We used individualized resting-state clusters identified by an SOM algorithm to corroborate previous findings of weaker posterior-anterior connectivity in the ASD group and examine age-related changes in the ASD and control groups. Thirty-nine adolescents with ASD and 41 controls underwent a 10-minute, eyes-open, resting-state functional MRI scan. The SOM analysis revealed that adolescents with ASD versus controls have weaker connectivity between the posterior hub of the default network and the right superior frontal gyrus. Additionally, controls have larger increases in connectivity with age compared to the ASD group. These findings indicate that SOM is a complementary method for calculating connectivity in a clinical population. Additionally, adolescents with ASD have a different developmental trajectory of the default network compared to controls.
Brain research 10/2010; 1380:187-97. DOI:10.1016/j.brainres.2010.10.102 · 2.84 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Restricted and repetitive behaviors (RRBs) observed during the Autism Diagnostic Observation Schedule [ADOS: Lord et al., 2000] were examined in a longitudinal data set of 455 toddlers and preschoolers (age 8-56 months) with clinical diagnosis of Autism Spectrum Disorders (ASD; autism, n=121 and pervasive developmental disorders-not otherwise specified (PDD-NOS), n=71), a nonspectrum disorder (NS; n=90), or typical development (TD; n=173). Even in the relatively brief semi-structured observations, GEE analyses of the severity and prevalence of RRBs differentiated children with ASD from those with NS and TD across all ages. RRB total scores on the ADOS were stable over time for children with ASD and NS; however, typically developing preschoolers showed lower RRB scores than typically developing toddlers. Nonverbal IQ (NVIQ) was more strongly related to the prevalence of RRBs in older children with PDD-NOS, NS, and TD than younger children under 2 years and those with autism. Item analyses revealed different relationships between individual items and NVIQ, age, diagnosis, and gender. These findings are discussed in terms of their implications for the etiology and treatment of RRBs as well as for the framework of ASD diagnostic criteria in future diagnostic systems.
Autism Research 08/2010; 3(4):162-73. DOI:10.1002/aur.142 · 4.33 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The autism spectrum disorders (ASDs) are a group of conditions characterized by impairments in reciprocal social interaction and communication, and the presence of restricted and repetitive behaviours. Individuals with an ASD vary greatly in cognitive development, which can range from above average to intellectual disability. Although ASDs are known to be highly heritable ( approximately 90%), the underlying genetic determinants are still largely unknown. Here we analysed the genome-wide characteristics of rare (<1% frequency) copy number variation in ASD using dense genotyping arrays. When comparing 996 ASD individuals of European ancestry to 1,287 matched controls, cases were found to carry a higher global burden of rare, genic copy number variants (CNVs) (1.19 fold, P = 0.012), especially so for loci previously implicated in either ASD and/or intellectual disability (1.69 fold, P = 3.4 x 10(-4)). Among the CNVs there were numerous de novo and inherited events, sometimes in combination in a given family, implicating many novel ASD genes such as SHANK2, SYNGAP1, DLGAP2 and the X-linked DDX53-PTCHD1 locus. We also discovered an enrichment of CNVs disrupting functional gene sets involved in cellular proliferation, projection and motility, and GTPase/Ras signalling. Our results reveal many new genetic and functional targets in ASD that may lead to final connected pathways.
[Show abstract][Hide abstract] ABSTRACT: This study characterized early language abilities in toddlers with autism spectrum disorders (n = 257) using multiple measures of language development, compared to toddlers with non-spectrum developmental delay (DD, n = 69). Findings indicated moderate to high degrees of agreement among three assessment measures (one parent report and two direct assessment measures). Performance on two of the three measures revealed a significant difference in the profile of receptive-expressive language abilities for toddlers with autism compared to the DD group, such that toddlers with autism had relatively more severe receptive than expressive language delays. Regression analyses examining concurrent predictors of language abilities revealed both similarities in significant predictors (nonverbal cognition) and differences (frequency of vocalization, imitation) across the diagnostic groups.
Journal of Autism and Developmental Disorders 03/2010; 40(10):1259-73. DOI:10.1007/s10803-010-0983-1 · 3.06 Impact Factor