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Autism spectrum disorders (ASD) are increasingly common neurodevelopmental disorders defined clinically by a triad of features including impairment in social interaction, impairment in communication in social situations and restricted and repetitive patterns of behavior and interests, with considerable phenotypic heterogeneity among individuals. Although heritability estimates for ASD are high, conventional genetic-based efforts to identify genes involved in ASD have yielded only few reproducible candidate genes that account for only a small proportion of ASDs. There is mounting evidence to suggest environmental and epigenetic factors play a stronger role in the etiology of ASD than previously thought. To begin to understand the contribution of epigenetics to ASD, we have examined DNA methylation (DNAm) in a pilot study of postmortem brain tissue from 19 autism cases and 21 unrelated controls, among three brain regions including dorsolateral prefrontal cortex, temporal cortex and cerebellum. We measured over 485,000 CpG loci across a diverse set of functionally relevant genomic regions using the Infinium HumanMethylation450 BeadChip and identified four genome-wide significant differentially methylated regions (DMRs) using a bump hunting approach and a permutation-based multiple testing correction method. We replicated 3/4 DMRs identified in our genome-wide screen in a different set of samples and across different brain regions. The DMRs identified in this study represent suggestive evidence for commonly altered methylation sites in ASD and provide several promising new candidate genes.

Although it is suspected that anxiety modifies the clinical presentation of autism in fragile X syndrome (FXS), neuropsychiatric co-morbidity profiles of these two disorders have not been extensively studied. The National Fragile X Survey was completed for 1,027 males with FXS, for whom yes/no information regarding the presence of several disorders is provided. Although the survey exhibited limited depth and lacked validation by standardized measures, this exploratory study was conducted to take advantage of the data as an opportunity for identifying future lines of inquiry. We addressed the following questions: (i) how do the co-morbidity profiles of FXS males with both autism and anxiety compare to those without anxiety?; (ii) do individuals with autism exhibit specific co-morbidity profiles compared to FXS males with anxiety only, or without either autism or anxiety?; (iii) how do co-morbidity profiles in children ages 3-11 differ from profiles of individuals >12 years? The group with autism and anxiety reported the highest prevalence of attention problems, hyperactivity/impulsivity, self-injurious behavior and aggressiveness. In addition, the lowest prevalence rates of these conditions were often observed in non-anxious groups regardless of autism status. Overall, this exploratory analysis generated several hypotheses for further study: (i) anxiety increases the severity of autism in FXS, particularly through additional behavioral abnormalities; (ii) some neuropsychiatric and behavioral conditions (i.e., attention problems, hyperactivity/impulsivity, aggressiveness) are primarily related to comorbid anxiety, not autism; (iii) prevalence of behavioral abnormalities increases with age. Future studies evaluating these hypotheses should incorporate validated neurobehavioral assessments, and control for cognitive level., (© 2014 Wiley Periodicals, Inc.)

Objectives: To examine patterns of autism spectrum disorder (ASD) inheritance and other features in twin pairs by zygosity, sex, and specific ASD diagnosis., Design: Cross-sectional study., Setting: Internet-based autism registry for US residents., Participants: Survey results from 277 twin pairs (210 dizygotic [DZ] and 67 monozygotic [MZ]) aged 18 years or younger with at least 1 affected twin., Main Exposures: Zygosity and sex., Outcome Measures: Concordance within twin pairs of diagnosis, natural history, and results from standardized autism screening., Results: Pairwise ASD concordance was 31% for DZ and 88% for MZ twins. Female and male MZ twins were 100% and 86% concordant, respectively, and DZ twin pairs with at least 1 female were less likely to be concordant (20%) than were male-male DZ twin pairs (40%). The hazard ratio for ASD diagnosis of the second twin after a first-twin diagnosis was 7.48 for MZ vs DZ twins (95% confidence interval, 3.8-14.7). Affected DZ individual twins had an earlier age at first parental concern and more frequent diagnoses of intellectual disability than did MZ twins; MZ twins had a higher prevalence of bipolar disorder and Asperger syndrome and higher concordance of the latter. Results of autism screening correlated with parent-reported ASD status in more than 90% of cases., Conclusions: Our data support greater ASD concordance in MZ vs DZ twins. Overall higher functioning, psychiatric comorbidity, and Asperger syndrome concordance among affected MZ vs DZ twins may also suggest differential heritability for different ASDs. For families in which one MZ twin is diagnosed with ASD, the second twin is unlikely to receive an ASD diagnosis after 12 months. In addition, Internet parent report of ASD status is valid.

We analyzed predictors of parent-reported initial diagnosis (autistic disorder [AD], pervasive developmental disorder-not otherwise specified [PDD-NOS], pervasive developmental disorder ['PDD'] and autism spectrum disorder ['ASD'], and Asperger syndrome [AS]), among 6,176 individuals with autism spectrum disorders diagnosed from 1994 through 2007. Overall, distribution of diagnoses was influenced by a secular time trend factor; other significant factors included ethnicity, white race, geographic location, urbanicity, and initial evaluator. Since 2001, most initial diagnoses of AD and AS have remained steady while 'PDD' and PDD-NOS have decreased. 'ASD' diagnoses have increased, especially among school-based teams; AS diagnoses also increased uniquely among these evaluators. Findings from this study suggest that current diagnostic guidelines may not be meeting all community evaluator needs.

The present study extends our previous work on characterizing the autistic behavior profile of boys with fragile X syndrome (FXS) who meet Diagnostic and Statistical Manual for Mental Disorders, 4th Edition criteria for autism spectrum disorder (ASD) into a longitudinal evaluation of ASD in FXS (FXS + ASD). Specifically, we aimed to determine the stability of the diagnosis and profile of ASD in FXS over time. Through regression models, we also evaluated which autistic and social behaviors and skills were correlates of diagnosis and autistic behavior severity (i.e., Autism Diagnostic Interview-Revised total scores). Finally, we assessed the evolution of cognitive parameters in FXS + ASD. A population of 56 boys (30-88 months at baseline) with FXS was evaluated using measures of autistic, social, and cognitive behaviors and skills at three yearly evaluations. We found that the diagnosis of ASD in FXS was relatively stable over time. Further emphasizing this stability, we found a set of behaviors and skills, particularly those related to peer relationships and adaptive socialization, that differentiated FXS + ASD from the rest of the FXS cohort (FXS + None) and contributed to autistic severity at all time points. Nevertheless, the general improvement in autistic behavior observed in FXS + ASD coupled with the concurrent worsening in FXS + None resulted in less differentiation between the groups over time. Surprisingly, FXS + ASD IQ scores were stable while FXS + None non-verbal IQ scores declined. Our findings indicate that ASD is a distinctive subphenotype in FXS characterized by deficits in complex social interaction, with similarities to ASD in the general population., ((c) 2009 Wiley-Liss, Inc.)

The overlap between autism and Rett syndrome clinical features has led to many cases of Rett syndrome being initially diagnosed with infantile autism or as having some autistic features. Both conditions seriously disrupt social and language development and are often accompanied by repetitive, nonpurposeful stereotypic hand movements. The aims of this study were to compare the early and subsequent clinical courses of female subjects with Rett syndrome categorised by whether or not a diagnosis of autism had been proposed before Rett syndrome had been diagnosed and compare the spectrum of methyl-CpG binding protein 2 (MECP2) mutations identified among the two groups. This study made use of a total of 313 cases recorded in two databases: the Australian Rett Syndrome Database (ARSD) and the International Rett Syndrome Phenotype Database (InterRett). Cases with an initial diagnosis of autism had significantly milder Rett syndrome symptoms and were more likely to remain ambulant, to have some functional hand use and not to have developed a scoliosis. Females with the p.R306C or p.T158M mutations in the MECP2 gene were more likely to have an initial diagnosis of autism, and the specific Rett syndrome symptoms were noted at a later age. We recommend that females who are initially considered to have autism be carefully monitored for the evolution of the signs and symptoms of Rett syndrome.

We conducted semiautomated, atlas-based analyses of regional brain volume changes on MRIs of children and adolescents with Down syndrome (DS) (N=15), DS with comorbid autism spectrum disorder (ASD) (N=15), and age-matched or sex-matched typically developing controls (N=22). Selective volumetric changes were correlated with neurobehavioral measures to determine their functional significance. DS involved selective reduction of frontal and parietal gray matter volumes, beyond the global microencephaly typically observed in this condition. DS with comorbid ASD involved relative hyperplasia of white matter in the cerebellum and brainstem compared with DS only. Cerebellar white matter volumes were positively correlated with severity of stereotypies, a distinctive feature of ASD in DS.

Social avoidance is a core phenotypic characteristic of fragile X syndrome (FXS) that has critical cognitive and social consequences. However, no study has examined modulation of multiple social avoidant behaviors in children with FXS. In the current study, we introduce the Social Approach Scale (SAS), an observation scale that includes physical movement, facial expression, and eye contact approach behaviors collected across multiple time points. Our findings suggested that social approach behaviors in children with FXS were affected by age, gender, setting, and time spent with an examiner. Selected social approach behaviors were related to autistic behavior. Increased eye contact over the course of a research assessment, in particular, was found to be a strong predictor of lower autistic behavior.

The present study extends our previous work characterizing the behavioral features of autistic-spectrum disorder (ASD) in Down syndrome (DS) using the Aberrant Behavior Checklist (ABC) and Autism Behavior Checklist (AutBehav). We examined which specific behaviors distinguished the behavioral phenotype of DS + ASD from other aberrant behavior disorders in DS, by determining the relative contribution of ABC and AutBehav subscales and items to the diagnosis of ASD. A total of 127 subjects (aged 2-24 years; mean age: 8.4 years; approximately 70% male), comprising: a cohort of 64 children and adolescents with DS and co-morbid ASD (DS + ASD), 19 with DS and stereotypic movement disorder (DS + SMD), 18 with DS and disruptive behaviors (DS + DB), and 26 with DS and no co-morbid behavior disorders (DS + none) were examined using the aforementioned measures of aberrant behavior. We found that subjects with DS + ASD showed the most severe aberrant behavior, especially stereotypy compared to DS + none and lethargy/social withdrawal and relating problems compared to DS + SMD. Specifically, relatively simple stereotypic behavior differentiated DS + ASD from DS + DB, whereas odd/bizarre stereotypic and anxious behavior characterized DS + ASD relative to DS + SMD and DS + none. Additionally, in a subset of subjects with DS + ASD and anxiety, social withdrawal was particularly pronounced. Overall, our findings indicate that a diagnosis of DS + ASD represents a distinctive set of aberrant behaviors marked by characteristic odd/bizarre stereotypic behavior, anxiety, and social withdrawal.

The present study extends our previous work on characterizing the profile of social behavior abnormalities in boys with Fragile X (FraX) and autism spectrum disorder (ASD) using clinically oriented behavioral rating scales and standardized instruments. The goal was to further distinguish behavioral parameters contributing to the diagnostic classification of FraX + ASD. The study design included two cohorts of boys with FraX (3-8 years), a larger main cohort for cross-sectional analyses (n = 56, 24 with ASD), and a longitudinal subset (n = 30, 11 with ASD) of the main cohort with up to 3 yearly observations. The focus was on the relative contribution of delayed adaptive socialization and social withdrawal, including item components of their corresponding rating instruments, to the diagnosis of ASD in boys with FraX. Using a combination of regression analyses, we demonstrated that: (1) as delayed socialization, social withdrawal is also a correlate of FraX + ASD; (2) items of social withdrawal scales representing avoidance were the main predictors of ASD status, particularly in older boys; (3) adaptive socialization skills reflecting rules of social behavior and recognition and labeling of emotions, linked to verbal reasoning abilities, were selectively associated with FraX + ASD; (4) adaptive socialization is the primary determinant over time of ASD status in boys with FraX; and (5) integrated adaptive socialization-social withdrawal models allow the identification of distinctive FraX + ASD subgroups. Altogether, our findings suggest that two distinct but interrelated social behavior abnormalities, one linked to impaired cognitive processes (delayed socialization) and the second one to disturbance in limbic circuits (avoidance), play a role in the development of ASD in boys with FraX.

To report on the cognitive and behavioral attributes of 61 children with Down syndrome (DS) and autistic-spectrum disorder (ASD) according to DSM-IV criteria; to determine the utility of the aberrant behavior checklist (ABC) to characterize these subjects for research purposes; and to test the hypothesis that subjects with DS + ASD could be distinguished from their typical DS peers using the ABC. Cross-sectional design. Cases with DS + ASD (N = 61), comparison group of DS + stereotypy movement disorder (SMD) (N = 26) and typical DS controls without behavior problems (N = 44) were ascertained and enrolled sequentially upon presentation to a DS clinic at an academic medical center over a 10-year period from 1991 to 2001. All subjects underwent neurodevelopmental and medical evaluation, and standardized cognitive testing. The parents provided responses to standardized behavioral questionnaires. Cognitive function (IQ) differed markedly across the three groups. The Lethary and Stereotypy subscales of the ABC were highly significant (P < 0.001) in distinguishing the three groups from one another. Within the ASD group differences were apparent by DSM-IV type on the Lethargy subscale, which reached significance, ANOVA (F = 0.002) and t-test (Autism > PDD, P = 0.005; PDD < CDD, P = 0.002). Using a multivariate regression model, the ABC scales alone explained 62% of variance of ASD outcome; addition of demographic variables explained up to 68% of the variance. There is good correlation between DSM-IV criteria for autism and subscales scores on the ABC in subjects with DS. This study demonstrates the feasibility of using the ABC to characterize the neurobehavioral phenotype of a cohort of children with trisomy 21 and ASD for ongoing research purposes., (2005 Wiley-Liss, Inc.)

The present study extends our previous work on social behavior impairment in young males with fragile X syndrome (FraX). Specifically, we evaluated whether the autistic phenomenon in FraX is expressed as a range of behavioral impairments as in idiopathic autism (Aut). We also examined whether there are behaviors, identified as items of the Autism Diagnostic Interview-Revised (ADI-R), that in FraX predispose to or differentiate subjects with autism spectrum disorder (ASD) diagnosis. Finally, regression models were utilized to test the relative contribution of reduced communication and socialization skills to ADI-R scores and diagnoses. A cohort of 56 boys (3-8 years) with FraX was examined in terms of scores on measures of cognition (IQ was a co-variate in most analyses.), autistic behavior, problem/aberrant behavior, adaptive behavior, and language development. We found that, indeed, in terms of problem behavior and adaptive skills, there is a range of severity from FraX + Aut to FraX + PDD (Pervasive Developmental Disorder) to FraX + none. ADI-R items representing "Play" types of interaction appear to be "susceptibility" factors since they were abnormal across the FraX cohort. Integrated regression models demonstrated that items reflecting complex social interaction differentiated the FraX + ASD (Aut + PDD) subgroup from the rest of the FraX cohort, while abnormalities in basic verbal and non-verbal communication distinguished the most severely affected boys with FraX + Aut from the milder FraX + PDD cohort. Models incorporating language, adaptive communication, and adaptive socialization skills revealed that socialization was not only the main influence on scores but also a predictor of ASD diagnosis. Altogether, our findings demonstrate that the diagnosis of ASD in FraX reflects, to a large extent, an impairment in social interaction that is expressed with variable severity in young males with FraX.

The present study characterizes distinctive and specific features of social behavior impairment, termed social behavior profile (SBP), in young males with fragile X syndrome (FraX). Fourteen males with FraX and autism (FraX+Aut), ages 3-8 years, were compared with either 41 FraX boys without autism (Aut), 7 age-matched males with developmental language delay and autism (DLD+Aut), or with 11 boys with non-selected (for language delay) idiopathic autism (IA), on several standardized instruments assessing social behavior and autistic features (i.e., autism diagnostic interview-revised, ADI-R). We found that FraX+Aut subjects displayed more impairment in overall cognition, problem/aberrant behavior, and adaptive behavior than the rest of the FraX cohort, even when individuals with pervasive developmental disorder (PDD) were included in the latter. Compared to both DLD+Aut and IA, FraX+Aut males were less impaired in ADI-R reciprocal social interaction (RECS) domain. However, boys with FraX+Aut were in general comparable to DLD+Aut subjects in problem/aberrant and adaptive behaviors. Based on the contrast between FraX+Aut and non-autistic FraX and DLD+Aut, we were able to identify measures (e.g., child behavior checklist (CBCL) withdrawn subscale) that better define social interaction impairment in FraX. Comparisons with DLD+Aut and IA led to the conclusion that communication impairment (COMM) and stereotypic behavior contribute relatively more to the diagnosis of autism in FraX+Aut. In agreement with recent studies, our data suggest that FraX+Aut, and more generally SBP, is a distinctive subphenotype among boys with FraX, which may share some pathophysiological mechanisms with IA., (Copyright 2004 Wiley-Liss, Inc.)

To gain insight into the specificity of cerebellar vermian abnormalities reported in autism, we conducted a magnetic resonance imaging (MRI) study of boys with either of two conditions associated with autism, Down syndrome and fragile X syndrome, compared with boys with idiopathic autism and controls. The subjects, ranging in age from 3 to 9 years, included 16 boys with Down syndrome + autism and 11 boys with Down syndrome only; 13 boys with fragile X syndrome + autism and 9 boys with fragile X syndrome only; 10 boys with idiopathic autism; and 22 controls. Diagnosis of autism was based on DSM-IV criteria, confirmed primarily by the Autism Diagnostic Interview. T1-weighted midsagittal MRIs were used to measure midline structures. Intracranial area, reflecting brain size, was significantly smaller in subjects with Down syndrome. Therefore, all vermian measures were expressed as ratios to intracranial area. Analysis of covariance (covarying for age and IQ) demonstrated that posterior vermi (lobules VI-VII and VIII-X) were markedly smaller in both Down syndrome groups and those with fragile X syndrome only, whereas only lobules VI-VII were reduced in idiopathic autism. Factorial analyses of variance tested interactions between autism factor and the diagnosis of Down syndrome or fragile X syndrome. The size of lobules VI-VII/intracranial area was dependent on autism status only in fragile X syndrome, with ratios significantly larger in fragile X syndrome with autism with respect to fragile X syndrome only. We conclude that selective posterior vermis hypoplasia is seen not only in idiopathic autism but also in Down syndrome and some individuals with fragile X syndrome. However, reductions in vermian lobules VI and VII appear to be specific to idiopathic autism, whereas increased size of lobules VI and VII is associated with autism in fragile X syndrome. The latter results are consistent with MRI studies showing lobules VI-VII hyperplasia in a subset of subjects with idiopathic autism and cerebral and hippocampal enlargements in fragile X syndrome.

In this study, we investigated the neuroanatomical similarities and differences between a pair of monozygotic, 7.5-year-old twin boys discordant for strictly defined autism, to identify neuroanatomical pathways that are impaired in individuals with autism. Although the unaffected twin did not fulfill the traditional diagnostic criteria for autism, he displayed constrictions in social interaction and play that were consistent with the broader phenotype for autism that has been described in nonautistic co-twins. Magnetic resonance imaging scans were obtained for each brother and compared with the scans of 5 age- and sex-matched unaffected peers. Quantitative analysis of brain anatomy revealed that the affected twin had markedly smaller caudate, amygdaloid, and hippocampal volumes, and smaller cerebellar vermis lobules VI and VII, in comparison with his brother. Both twins evidenced disproportionately reduced volumes of the superior temporal gyrus and the frontal lobe relative to the comparison sample. The results suggest the dysfunction of two separate but overlapping neuroanatomical pathways, ie, one subcortical network differentiating the twins from each other that may underlie the traditional neurobehavioral phenotype for strictly defined autism, and a second cortical network differentiating the twins from the comparison sample that may lead to the broader phenotype for autism.