Search

Objective: Autism spectrum disorder is characterized by deficits in social function and the presence of repetitive and restrictive behaviors. Following a previous test of principle, the authors adopted a quantitative approach to discovering genes contributing to the broader autism phenotype by using social responsiveness as an endophenotype for autism spectrum disorder., Method: Linkage analyses using scores from the Social Responsiveness Scale were performed in 590 families from the Autism Genetic Resource Exchange, a largely multiplex autism spectrum disorder cohort. Regional and genomewide association analyses were performed to search for common variants contributing to social responsiveness., Results: Social Responsiveness Scale scores were unimodally distributed in male offspring from multiplex autism families, in contrast with a bimodal distribution observed in female offspring. In correlated analyses differing by Social Responsiveness Scale respondent, genomewide significant linkage for social responsiveness was identified at chr8p21.3 (multipoint LOD=4.11; teacher/parent scores) and chr8q24.22 (multipoint LOD=4.54; parent-only scores), respectively. Genomewide or linkage-directed association analyses did not detect common variants contributing to social responsiveness., Conclusions: The sex-differential distributions of Social Responsiveness Scale scores in multiplex autism families likely reflect mechanisms contributing to the sex ratio for autism observed in the general population and form a quantitative signature of reduced penetrance of inherited liability to autism spectrum disorder among females. The identification of two strong loci for social responsiveness validates the endophenotype approach for the identification of genetic variants contributing to complex traits such as autism spectrum disorder. While causal mutations have yet to be identified, these findings are consistent with segregation of rare genetic variants influencing social responsiveness and underscore the increasingly recognized role of rare inherited variants in the genetic architecture of autism spectrum disorder.

Importance: Although autism spectrum disorder (ASD) is known to be heritable, patterns of inheritance of subclinical autistic traits in nonclinical samples are poorly understood., Objective: To examine the familiality of Social Responsiveness Scale (SRS) scores of individuals with and without ASD., Design, Setting, and Participants: We performed a nested case-control study (pilot study: July 1, 2007, through June 30, 2009; full-scale study: September 15, 2008, through September 14, 2012) within a population-based longitudinal cohort. Participants were drawn from the Nurses' Health Study II, a cohort of 116,430 female nurses recruited in 1989. Case participants were index children with reported ASD; control participants were frequency matched by year of birth of case participants among those not reporting ASD. Of 3161 eligible participants, 2144 nurses (67.8%) returned SRS forms for a child and at least 1 parent and were included in these analyses., Exposure: The SRS scores, as reported by nurse mothers and their spouses, were examined in association with risk of ASD using crude and adjusted logistic regression analyses. The SRS scores of the children were examined in association with SRS scores of the parents using crude and adjusted linear regression analyses stratified by case status., Main Outcomes and Measures: Autism spectrum disorder, assessed by maternal report, validated in a subgroup with the Autism Diagnostic Interview-Revised., Results: A total of 1649 individuals were included in these analyses, including 256 ASD case participants, 1393 control participants, 1233 mothers, and 1614 fathers. Risk of ASD was increased by 85.0% among children whose parents had concordantly elevated SRS scores (odds ratio [OR], 1.85; 95% CI, 1.08-3.16) and by 52.0% when the score of either parent was elevated (OR, 1.52; 95% CI, 1.11-2.06). Elevated scores of the father significantly increased the risk of ASD in the child (OR, 1.94; 95% CI, 1.38-2.71), but no association was seen with elevated scores of the mother. Elevated parent scores significantly increased child scores in controls, corresponding to an increase in 23 points (P < .001)., Conclusions and Relevance: These findings support the role of additive genetic influences in concentrating inherited ASD susceptibility in successive generations and the potential role of preferential mating, and suggest that typical variation in parental social functioning can produce clinically significant differences in offspring social traits.

Demographic and clinical factors may influence assessment of autism symptoms. This study evaluated these correlates and also examined whether social communication and interaction and restricted/repetitive behavior provided unique prediction of autism spectrum disorder diagnosis. We analyzed data from 7352 siblings included in the Interactive Autism Network registry. Social communication and interaction and restricted/repetitive behavior symptoms were obtained using caregiver-reports on the Social Responsiveness Scale. Demographic and clinical correlates were covariates in regression models predicting social communication and interaction and restricted/repetitive behavior symptoms. Logistic regression and receiver operating characteristic curve analyses evaluated the incremental validity of social communication and interaction and restricted/repetitive behavior domains over and above global autism symptoms. Autism spectrum disorder diagnosis was the strongest correlate of caregiver-reported social communication and interaction and restricted/repetitive behavior symptoms. The presence of comorbid diagnoses also increased symptom levels. Social communication and interaction and restricted/repetitive behavior symptoms provided significant, but modest, incremental validity in predicting diagnosis beyond global autism symptoms. These findings suggest that autism spectrum disorder diagnosis is by far the largest determinant of quantitatively measured autism symptoms. Externalizing (attention deficit hyperactivity disorder) and internalizing (anxiety) behavior, low cognitive ability, and demographic factors may confound caregiver-report of autism symptoms, potentially necessitating a continuous norming approach to the revision of symptom measures. Social communication and interaction and restricted/repetitive behavior symptoms may provide incremental validity in the diagnosis of autism spectrum disorder., (© The Author(s) 2013.)

Objective: First-degree relatives of persons with an autism spectrum disorder (ASD) are at increased risk for ASD-related characteristics. As little is known about the early expression of these characteristics, this study characterizes the non-ASD outcomes of 3-year-old high-risk (HR) siblings of children with ASD., Method: Two groups of children without ASD participated: 507 HR siblings and 324 low-risk (LR) control subjects (no known relatives with ASD). Children were enrolled at a mean age of 8 months, and outcomes were assessed at 3 years. Outcome measures were Autism Diagnostic Observation Schedule (ADOS) calibrated severity scores, and Mullen Verbal and Non-Verbal Developmental Quotients (DQ)., Results: At 3 years, HR siblings without an ASD outcome exhibited higher mean ADOS severity scores and lower verbal and non-verbal DQs than LR controls. HR siblings were over-represented (21% HR versus 7% LR) in latent classes characterized by elevated ADOS severity and/or low to low-average DQs. The remaining HR siblings without ASD outcomes (79%) belonged to classes in which they were not differentially represented with respect to LR siblings., Conclusions: Having removed a previously identified 18.7% of HR siblings with ASD outcomes from all analyses, HR siblings nevertheless exhibited higher mean levels of ASD severity and lower levels of developmental functioning than LR children. However, the latent class membership of four-fifths of the HR siblings was not significantly different from that of LR control subjects. One-fifth of HR siblings belonged to classes characterized by higher ASD severity and/or lower levels of developmental functioning. This empirically derived characterization of an early-emerging pattern of difficulties in a minority of 3-year-old HR siblings suggests the importance of developmental surveillance and early intervention for these children., (Copyright © 2013 American Academy of Child and Adolescent Psychiatry. Published by Elsevier Inc. All rights reserved.)

To explore mechanisms underlying reduced fixation of eyes in autism, children with autistic spectrum disorders (ASD) and typically developing children were tested in five visual search experiments: simple color feature; color-shape conjunction; face in non-face objects; mouth region; and eye region. No group differences were found for reaction time profile shapes in any of the five experiments, suggesting intact basic search mechanics in children with ASD. Contrary to early reports in the literature, but consistent with other more recent findings, we observed no superiority for conjunction search in children with ASD. Importantly, children with ASD did show reduced accuracy for eye region search (p = .005), suggesting that eyes contribute less to high-level face representations in ASD or that there is an eye region-specific disruption to attentional processes engaged by search in ASD.

Objective: The recurrence risk of autism spectrum disorders (ASD) is estimated to be between 3% and 10%, but previous research was limited by small sample sizes and biases related to ascertainment, reporting, and stoppage factors. This study used prospective methods to obtain an updated estimate of sibling recurrence risk for ASD., Methods: A prospective longitudinal study of infants at risk for ASD was conducted by a multisite international network, the Baby Siblings Research Consortium. Infants (n = 664) with an older biological sibling with ASD were followed from early in life to 36 months, when they were classified as having or not having ASD. An ASD classification required surpassing the cutoff of the Autism Diagnostic Observation Schedule and receiving a clinical diagnosis from an expert clinician., Results: A total of 18.7% of the infants developed ASD. Infant gender and the presence of >1 older affected sibling were significant predictors of ASD outcome, and there was an almost threefold increase in risk for male subjects and an additional twofold increase in risk if there was >1 older affected sibling. The age of the infant at study enrollment, the gender and functioning level of the infant's older sibling, and other demographic factors did not predict ASD outcome., Conclusions: The sibling recurrence rate of ASD is higher than suggested by previous estimates. The size of the current sample and prospective nature of data collection minimized many limitations of previous studies of sibling recurrence. Clinical implications, including genetic counseling, are discussed.

Objective: Comparative studies of social responsiveness, an ability that is impaired in autism spectrum disorders, can inform our understanding of both autism and the cognitive architecture of social behavior. Because there is no existing quantitative measure of social responsiveness in chimpanzees, we generated a quantitative, cross-species (human-chimpanzee) social responsiveness measure., Method: We translated the Social Responsiveness Scale (SRS), an instrument that quantifies human social responsiveness, into an analogous instrument for chimpanzees. We then retranslated this "Chimpanzee SRS" into a human "Cross-Species SRS" (XSRS). We evaluated three groups of chimpanzees (n = 29) with the Chimpanzee SRS and typical and human children with autism spectrum disorder (ASD; n = 20) with the XSRS., Results: The Chimpanzee SRS demonstrated strong interrater reliability at the three sites (ranges for individual ICCs: 0.534 to 0.866; mean ICCs: 0.851 to 0.970). As has been observed in human beings, exploratory principal components analysis of Chimpanzee SRS scores supports a single factor underlying chimpanzee social responsiveness. Human subjects' XSRS scores were fully concordant with their SRS scores (r = 0.976, p = .001) and distinguished appropriately between typical and ASD subjects. One chimpanzee known for inappropriate social behavior displayed a significantly higher score than all other chimpanzees at its site, demonstrating the scale's ability to detect impaired social responsiveness in chimpanzees., Conclusion: Our initial cross-species social responsiveness scale proved reliable and discriminated differences in social responsiveness across (in a relative sense) and within (in a more objectively quantifiable manner) human beings and chimpanzees., (Copyright © 2011 American Academy of Child and Adolescent Psychiatry. Published by Elsevier Inc. All rights reserved.)

Depressive syndromes represent a disabling comorbidity for many children with autism spectrum disorders (ASD); however, the ascertainment of depression can be complicated by phenotypic overlap between the 2 conditions, by ways in which autistic symptomatology can mask cardinal features of depression and by atypical manifestations of depression in children with ASD. These issues have contributed to wide variation in the estimation of prevalence rates of depression in individuals with ASD and invoke the need for new approaches to the specific detection of depression and other neuropsychiatric comorbidities that aggregate in children affected by ASD. The authors review the scientific literature relevant to the occurrence of depression in ASD and consider important parameters of risk, including psychosocial factors such as insight into affectation status, as well as biological factors such as the aggregation of depressive syndromes in certain families affected by autism, which has suggested possible overlap in genetic influences underlying the 2 conditions. Variability in the manifestations of depression across environmental contexts provides important clues to intervention and underscores the potential importance of involving multiple informants in ascertaining depression in children and adolescents with ASD. A practical strategy for evaluating the presence of depression in youth with ASD is synthesized from the available data and discussed.

Objective: Although the symptoms of autism exhibit quantitative distributions in nature, estimates of recurrence risk in families have never previously considered or incorporated quantitative characterization of the autistic phenotype among siblings., Method: The authors report the results of quantitative characterization of 2,920 children from 1,235 families participating in a national volunteer register, with at least one child clinically affected by an autism spectrum disorder and at least one full biological sibling., Results: A traditionally defined autism spectrum disorder in an additional child occurred in 10.9% of the families. An additional 20% of nonautism-affected siblings had a history of language delay, one-half of whom exhibited autistic qualities of speech. Quantitative characterization using the Social Responsiveness Scale supported previously reported aggregation of a wide range of subclinical (quantitative) autistic traits among otherwise unaffected children in multiple-incidence families and a relative absence of quantitative autistic traits among siblings in single-incidence families. Girls whose standardized severity ratings fell above a first percentile severity threshold (relative to the general population distribution) were significantly less likely to have elicited community diagnoses than their male counterparts., Conclusions: These data suggest that, depending on how it is defined, sibling recurrence in autism spectrum disorder may exceed previously published estimates and varies as a function of family type. The results support differences in mechanisms of genetic transmission between simplex and multiplex autism and advance current understanding of the genetic epidemiology of autism spectrum conditions.

While strong familial evidence supports a substantial genetic contribution to the etiology of autism spectrum disorders (ASD), specific genetic abnormalities have been identified in only a small minority of all cases. In order to comprehensively delineate the genetic components of autism including the identification of rare and common variants, overall sample sizes an order of magnitude larger than those currently under study are critically needed. This will require rapid and scalable subject assessment paradigms that obviate clinic-based time-intensive behavioral phenotyping, which is a rate-limiting step. Here, we test the accuracy of a web-based approach to autism phenotyping implemented within the Interactive Autism Network (IAN). Families who were registered with the IAN and resided near one of the three study sites were eligible for the study. One hundred seven children ascertained from this pool who were verbal, age 4-17 years, and had Social Communication Questionnaire (SCQ) scores > or =12 (a profile that characterizes a majority of ASD-affected children in IAN) underwent a clinical confirmation battery. One hundred five of the 107 children were ASD positive (98%) by clinician's best estimate. One hundred four of these individuals (99%) were ASD positive by developmental history using the Autism Diagnostic Interview-Revised (ADI-R) and 97 (93%) were positive for ASD by developmental history and direct observational assessment (Autism Diagnostic Observational Schedule or expert clinician observation). These data support the reliability and feasibility of the IAN-implemented parent-report paradigms for the ascertainment of clinical ASD for large-scale genetic research., ((c) 2010 Wiley-Liss, Inc.)

The present study evaluated the hypothesis that autism spectrum disorders (ASDs) are best represented as a discrete category distinct from typical behavior within autism-affected families. The latent structure, categorical versus dimensional, of ASDs informs future diagnostic revisions, clinical assessment, and the design of future research. Data were obtained from Interactive Autism Network, a registry that preferentially recruits families with at least one ASD-affected child. Caregivers reported autism symptoms for affected and unaffected children using the Social Responsiveness Scale and Social Communication Questionnaire. Taxometric and latent variable models examined whether dimensional or categorical models best fit the data. Taxometric and latent variable model comparisons consistently indicated two-group mixtures for all indicator sets, even in participants designated as unaffected by caregivers. The identified category was associated with external indicators of disability, supporting its validity. Results indicated that ASD is best characterized as a category, distinct from typical behavior within ASD-affected families.

Objective: Sibling recurrence risk in autism has been estimated to be approximately 10%. This study investigated subsyndromal autistic impairments among siblings of probands with pervasive developmental disorders., Method: The authors used the Social Responsiveness Scale to obtain quantitative assessments of autistic social impairment in three groups of proband-sibling pairs: 1) autistic children from multiple-incidence families and their closest in age nonautistic brothers (N=49 pairs); 2) children with any pervasive developmental disorder, including autism, and their closest-in-age brothers (N=100 pairs), and 3) children with psychopathology unrelated to autism and their closest-in-age brothers (N=45 pairs)., Results: Sibling Social Responsiveness Scale scores were continuously distributed and substantially elevated for both the autistic and pervasive developmental disorder groups. Highest scores (i.e., greatest impairment) were seen among siblings of autistic probands from multiple-incidence families, followed by siblings of probands with any pervasive developmental disorder, then siblings of probands with psychopathology unrelated to autism., Conclusions: Taken together with previous findings, these results support the notion that genetic susceptibility factors responsible for common, subsyndromal social impairments may be related to the causes of categorically defined pervasive developmental disorders.

Studies of the broader autism phenotype, and of subtle changes in autism symptoms over time, have been compromised by a lack of established quantitative assessment tools. The Social Responsiveness Scale (SRS-formerly known as the Social Reciprocity Scale) is a new instrument that can be completed by parents and/or teachers in 15-20 minutes. We compared the SRS with the Autism Diagnostic Interview-Revised (ADI-R) in 61 child psychiatric patients. Correlations between SRS scores and ADI-R algorithm scores for DSM-IV criterion sets were on the order of 0.7. SRS scores were unrelated to I.Q. and exhibited inter-rater reliability on the order of 0.8. The SRS is a valid quantitative measure of autistic traits, feasible for use in clinical settings and for large-scale research studies of autism spectrum conditions.

An invariant feature of pervasive developmental disorders (PDDs) is a relative deficit in the capacity for reciprocal social behavior (RSB). The authors acquired teacher reports of RSB in 287 schoolchildren and parent reports of RSB in 158 child psychiatric patients using a new research instrument, the Social Reciprocity Scale. Total scores on this measure of RSB were continuously distributed in all groups of subjects; children with PDDs scored significantly higher for the degree of deficits in RSB than did clinical or nonclinical controls. Latent class analysis and factor analysis failed to demonstrate separate categories of deficiency for core autistic symptomatology and more general impairments in RSB, consistent with the notion of a "broader autism phenotype." Assessments of RSB on a continuous scale may be useful clinically for characterizing the behavior of children whose social deficits fall below the threshold for a full diagnosis of autism. They may also be useful in genetic-linkage studies of autistic spectrum disorders.