The familial aggregation of the lesser variant in biological and nonbiological relatives of PDD probands: a family history study

Endophenotype trait domains for advancing gene discovery in autism spectrum disorder

Autism spectrum disorder (ASD) is associated with a diverse range of etiological processes, including both genetic and non-genetic causes. For a plurality of individuals with ASD, it is likely that the primary causes involve multiple common inherited variants that individually account for only small levels of variation in phenotypic outcomes. This genetic landscape creates a major challenge for detecting small but important pathogenic effects associated with ASD. To address similar challenges, separate fields of medicine have identified endophenotypes, or discrete, quantitative traits that reflect genetic likelihood for a particular clinical condition and leveraged the study of these traits to map polygenic mechanisms and advance more personalized therapeutic strategies for complex diseases. Endophenotypes represent a distinct class of biomarkers useful for understanding genetic contributions to psychiatric and developmental disorders because they are embedded within the causal chain between genotype and clinical phenotype, and they are more proximal to the action of the gene(s) than behavioral traits. Despite their demonstrated power for guiding new understanding of complex genetic structures of clinical conditions, few endophenotypes associated with ASD have been identified and integrated into family genetic studies. In this review, we argue that advancing knowledge of the complex pathogenic processes that contribute to ASD can be accelerated by refocusing attention toward identifying endophenotypic traits reflective of inherited mechanisms. This pivot requires renewed emphasis on study designs with measurement of familial co-variation including infant sibling studies, family trio and quad designs, and analysis of monozygotic and dizygotic twin concordance for select trait dimensions. We also emphasize that clarification of endophenotypic traits necessarily will involve integration of transdiagnostic approaches as candidate traits likely reflect liability for multiple clinical conditions and often are agnostic to diagnostic boundaries. Multiple candidate endophenotypes associated with ASD likelihood are described, and we propose a new focus on the analysis of "endophenotype trait domains" (ETDs), or traits measured across multiple levels (e.g., molecular, cellular, neural system, neuropsychological) along the causal pathway from genes to behavior. To inform our central argument for research efforts toward ETD discovery, we first provide a brief review of the concept of endophenotypes and their application to psychiatry. Next, we highlight key criteria for determining the value of candidate endophenotypes, including unique considerations for the study of ASD. Descriptions of different study designs for assessing endophenotypes in ASD research then are offered, including analysis of how select patterns of results may help prioritize candidate traits in future research. We also present multiple candidate ETDs that collectively cover a breadth of clinical phenomena associated with ASD, including social, language/communication, cognitive control, and sensorimotor processes. These ETDs are described because they represent promising targets for gene discovery related to clinical autistic traits, and they serve as models for analysis of separate candidate domains that may inform understanding of inherited etiological processes associated with ASD as well as overlapping neurodevelopmental disorders.

Toward the detection of reduced emotion expression intensity: an autism sibling study

INTRODUCTION

Expressing emotions through spontaneous facial expression is an important nonverbal social communication skill. In our study, we aimed to demonstrate that both children with autism spectrum disorder (ASD) and the non-ASD siblings of children with ASD have deficits in this skill.

METHOD

In this study, we analyzed the six core facial emotion expressions of three distinct groups of children - those diagnosed with ASD (n = 60), non-ASD siblings (n = 60), and typically developed children (n = 60). To analyze facial expressions, we employed a computer vision program that uses machine learning algorithms to detect facial features and conducted an evidence-based task that involved assessing participants' ability to recognize facial emotion expressions.

RESULTS

Deficits in spontaneous emotion expression were shown in the children with ASD and in non-ASD siblings when compared with typically developed children. Interestingly, it was determined that these deficits were not related to the severity of the autism symptoms in the ASD group.

CONCLUSIONS

The results of the study suggest that computer-based automated analysis of facial expressions with contextual social scenes task holds potential for measuring limitations in the ability to express emotions, and they supplement the traditional clinical assessment of social phenotypical behavior deficits. This applies both to children with ASD and especially, to the non-ASD siblings of children with ASD. This study adds a novel approach to previous literature examining the emotion expression skills.

Childhood Academic Performance: A Potential Marker of Genetic Liability to Autism

Autism spectrum disorder (ASD), a heritable neurodevelopmental disorder, confers genetic liability that is often expressed among relatives through subclinical, genetically-meaningful traits, or endophenotypes. For instance, relative to controls, parents of individuals with ASD differ in language-related skills, with differences emerging in childhood. To examine ASD-related endophenotypes, this study investigated developmental academic profiles among clinically unaffected siblings of individuals with ASD (n = 29). Lower performance in language-related skills among siblings mirrored previously-reported patterns among parents, which were also associated with greater subclinical ASD-related traits in themselves and their parents, and with greater symptom severity in their sibling with ASD. Findings demonstrated specific phenotypes, derived from standardized academic testing, that may represent childhood indicators of genetic liability to ASD in first-degree relatives.

Auditory Pitch Perception in Autism Spectrum Disorder: A Systematic Review and Meta-Analysis

PURPOSE

Pitch plays an important role in auditory perception of music and language. This study provides a systematic review with meta-analysis to investigate whether individuals with autism spectrum disorder (ASD) have enhanced pitch processing ability and to identify the potential factors associated with processing differences between ASD and neurotypicals.

METHOD

We conducted a systematic search through six major electronic databases focusing on the studies that used nonspeech stimuli to provide a qualitative and quantitative assessment across existing studies on pitch perception in autism. We identified potential participant- and methodology-related moderators and conducted metaregression analyses using mixed-effects models.

RESULTS

On the basis of 22 studies with a total of 464 participants with ASD, we obtained a small-to-medium positive effect size (g = 0.26) in support of enhanced pitch perception in ASD. Moreover, the mean age and nonverbal IQ of participants were found to significantly moderate the between-studies heterogeneity.

CONCLUSIONS

Our study provides the first meta-analysis on auditory pitch perception in ASD and demonstrates the existence of different developmental trajectories between autistic individuals and neurotypicals. In addition to age, nonverbal ability is found to be a significant contributor to the lower level/local processing bias in ASD. We highlight the need for further investigation of pitch perception in ASD under challenging listening conditions. Future neurophysiological and brain imaging studies with a longitudinal design are also needed to better understand the underlying neural mechanisms of atypical pitch processing in ASD and to help guide auditory-based interventions for improving language and social functioning.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.21614271.

A case of catatonia in the aftermath of the COVID-19 pandemic: does autism spectrum matter?

BACKGROUND

There is growing concern about the psychopathological consequences of the COVID-19 pandemic. The prolonged stress due to the spreading fear of the contagion and to the enforced containment measures are deemed to trigger recurrences of preexisting mental disorders as well as the onset of new ones. From such perspective, clinical cases may be of primary ground to identify individual features and pandemic-related factors predisposing to the development of serious psychiatric symptoms.

CASE PRESENTATION

Mr. R. is a 64-year-old, married, unemployed man, whose premorbid personality was characterized by relevant autistic traits. The patient developed catatonia in the context of the COVID-19 pandemic. We aimed at discussing the role of both preexisting and precipitating factors.

CONCLUSIONS

Autism spectrum could represent a predisposing factor for severe psychopathological outcome and catatonia. Furthermore, the present clinical case highlights the role of COVID-19 pandemic in influencing physical and mental health.

Three decades of ASD genetics: Building a foundation for neurobiological understanding and treatment

Methodological advances over the last three decades have led to a profound transformation in our understanding of the genetic origins of neuropsychiatric disorders. This is exemplified by the study of autism spectrum disorders (ASD) for which microarrays, whole exome sequencing (WES) and whole genome sequencing (WGS) have yielded over a hundred causal loci. Genome-wide association studies (GWAS) in ASD have also been fruitful, identifying 5 genome-wide significant loci thus far and demonstrating a substantial role for polygenic inherited risk. Approaches rooted in systems biology and functional genomics have increasingly placed genes implicated by risk variants into biological context. Genetic risk affects a finite group of cell-types and biological processes, converging primarily on early stages of brain development (though, the expression of many risk genes persists through childhood). Coupled with advances in stem cell-based human in vitro model systems, these findings provide a basis for developing mechanistic models of disease pathophysiology.

The broad autism phenotype in real-life: clinical and functional correlates of autism spectrum symptoms and rumination among parents of patients with autism spectrum disorder

OBJECTIVE

Increasing literature reported higher rates of psychiatric disorders in parents of children with autism spectrum disorder (ASD), as well as of autistic-like features in social and cognitive functioning. However, little attention has been paid to the association between autistic traits (AT) and global functioning in this population. The aim of the present work was to investigate clinical and functional correlates of AT among parents of ASD children, with a specific focus on ruminative thinking.

METHODS

One hundred and twenty parents of ASD children were assessed by the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders (DSM-5), the Adult Autism Subthreshold Spectrum (AdAS Spectrum), the Ruminative Response Scale (RRS), the Social and Occupational Functioning Assessment Scale (SOFAS).

RESULTS

Subjects with at least 1 psychiatric disorder (39.2%) showed significantly higher AdAS Spectrum and RRS scores. Subjects with a history of school difficulties and with language development alterations scored significantly higher on specific AdAS Spectrum domains. A significant negative correlation was found between SOFAS and AdAS Spectrum scores, as well as between SOFAS and RRS scores. AdAS Spectrum nonverbal communication domain score was identified has a statistically predictive variable for the presence of psychiatric disorders and lower SOFAS scores. Finally, we found a significant indirect effect of AdAS total score on SOFAS score, which was fully mediated by RRS total score.

CONCLUSIONS

AT in parents of ASD children seem to be associated with a higher vulnerability toward psychopathology and with a lower global functioning. Ruminative thinking may play a role in the relationship between AT and functional outcome.

Mentalising Moderates the Link between Autism Traits and Current Gender Dysphoric Features in Primarily Non-autistic, Cisgender Individuals

The co-occurrence between autism and gender dysphoria has received much attention recently. We found that, among 101 adults from the general population number of autism traits, as measured using the autism-spectrum quotient was associated significantly with recalled and current gender dysphoric traits. Furthermore, performance on an objective measure of mentalising, such as the “Reading the Mind in the Eyes” test was associated with current gender dysphoric traits, but most importantly it moderated the relation between number of autism traits and number of current gender dysphoric traits, such that the association was significant only when mentalising ability was relatively low. Results suggest mentalising may represent a contributing factor to the relation between autism and gender dysphoric traits in the general population.

Alexithymia Profile in Relation to Negative Affect in Parents of Autistic and Typically Developing Young Children

In our study, we explored the construct of alexithymia in parents of children with and without ASD using a multi-method approach based on self-rated and external rater assessment. We also assessed the level of self-report measures of negative affect states such as trait anxiety and depression, and investigated the correlation between the alexithymia construct, trait anxiety, and depression within the broader autism phenotype (BAP). A total sample of 100 parents (25 mothers and 25 fathers in each group) were administered the TAS-20 and the TSIA to measure self-reported and observer-rated alexithymia traits, as well as self-report measures of anxiety and depression. Study results showed that the TSIA but not the TAS-20 was able to detect significant group differences in alexithymia traits among parents of children with and without ASD, with parents of ASD children displaying significantly higher levels of alexithymia. Furthermore, differently from the TAS-20, no significant correlations between the TSIA and measures of anxiety and depression were detected. Taken together, our results suggest the importance of using multi-method approaches to control for potential measurement bias and to detect psychological constructs such as alexithymia in subclinical samples such as parents of children with ASD.

Cognitive and behavioral differences in toddlers with autism spectrum disorder from multiplex and simplex families

Prospective, longitudinal designs utilizing "high-risk" infant siblings of children diagnosed with Autism Spectrum Disorder (ASD-sibs) have provided unique and valuable insights regarding the early ASD phenotype. However, it remains unclear whether these cases are representative of all children with ASD. The objective in the present study was to investigate whether the early development of toddlers with ASD from multiplex (MPX) families, who have an affected older sibling, is similar or different to toddlers with ASD from simplex (SPX) families, where there is no affected sibling. A further aim was to examine patterns of association between autism symptom severity and cognitive functioning within each group to inform possible mechanisms for group similarities/differences. Behavioral and cognitive assessment data from a sample of toddlers with ASD was utilized, comprising 45 MPX, 127 first-born SPX, and 72 later-born SPX toddlers. Participants in the MPX group had significantly higher developmental quotients on the Mullen Scales of Early Learning compared to those in the SPX groups, who did not differ from each other. However, all three groups were similar on their autism severity scores (measured using the Autism Diagnostic Observation Schedule and the Autism Diagnostic Interview), and the pattern of relationships between cognitive ability and autism symptom severity. The results suggest that caution be exercised in generalizing findings from ASD-sib samples to other samples of children with ASD. The higher cognitive abilities in the MPX group, in addition to biological differences, may also be an outcome of family environmental factors, which deserves further investigation. Autism Research 2019, 12: 682-693. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: We sought to establish whether toddlers with autism from families where there is more than one affected child, called multiplex families, are different to children from simplex families, where there is only one affected child, and no other members within the immediate family with an autism diagnosis. We found that while toddlers from multiplex families were similar to those from simplex families in their autism symptoms, they were more developmentally advanced than children in the latter group.

Broader autism phenotype in parents of children with autism: a systematic review of percentage estimates

The broader autism phenotype (BAP) is a collection of sub-diagnostic autistic traits more common in families of individuals with autism spectrum disorder (ASD) than in the general population. BAP is a latent construct that can be defined using different domains, measured using multiple instruments, and reported using different techniques. Therefore, estimates of BAP may vary greatly across studies. Our objective was to systematically review studies that reported occurrence of BAP in parents of children with ASD in order to quantify and describe heterogeneity in estimates. We systematically searched PubMed and Scopus using PRISMA guidelines for studies quantifying percentage of parents of children with ASD who had BAP We identified 41 studies that measured BAP in parents of children with ASD. These studies used eight different instruments, four different forms of data collection, and had a wide range of sample sizes (N=4 to N=3299). Percentage with BAP ranged from 2.6% to 80%. BAP was more prevalent in fathers than mothers. Parental BAP may be an important tool for parsing heterogeneity in ASD etiology and for developing parent-mediated ASD interventions. However, the variety in measurement instruments and variability in study samples limits our ability to synthesize estimates. To improve measurement of BAP and increase consistency across studies, universal methods should be accepted and adopted across studies. A more consistent approach to BAP measurement may enable efficient etiologic research that can be meta-analyzed and may allow for a larger evidence base that can be used to account for BAP when developing parent-mediated interventions.

Alexithymia, depression and anxiety in parents of children with neurodevelopmental disorder: Comparative study of autistic disorder, pervasive developmental disorder not otherwise specified and attention deficit-hyperactivity disorder

BACKGROUND

Recent studies have shown that individuals with neurodevelopmental disorders and their relatives have problems expressing and recognizing emotions, but there is a lack of studies on alexithymia, and the relationship between parental alexithymia and depression-anxiety symptoms in these groups. The aim of this study was therefore to measure alexithymia, depression, and anxiety levels in parents of children with pervasive developmental disorders and attention deficit-hyperactivity disorder (ADHD), and determine whether there is a positive correlation between the child's neurodevelopmental problem severity and parent scores.

METHODS

Parents of 29 autistic disorder (AD), 28 pervasive developmental disorder not otherwise specified (PDD-NOS) and 29 ADHD children were recruited into the study, and completed a demographic information form, as well as the Toronto Alexithymia Scale (TAS-20), Beck Depression Inventory, and State-Trait Anxiety Inventory.

RESULTS

Alexithymia symptoms were higher in parents of children with AD than in others but unexpectedly, also these symptoms were higher in ADHD parents than in PDD-NOS groups. In addition, there were unexpected differences according to alexithymia subtype, while only the difference in maternal TAS-1 scores (difficulty in describing feelings) were statistically significant. Parental depression and state anxiety scores were increased as the child's symptom severity increased, but trait anxiety symptoms were higher in the AD and ADHD group than in the PDD-NOS group. In all groups, maternal depression and anxiety scores were higher than paternal scores, and differences were significant for depression and anxiety types in AD, and for only anxiety types in ADHD parents. The AD group had the strongest correlation between parental depression-anxiety and alexithymia.

CONCLUSION

The possibility of alexithymia, depression and anxiety should be kept in mind when working with parents of children with neurodevelopmental disorders.

The Broader Autism Phenotype in Mothers is Associated with Increased Discordance Between Maternal-Reported and Clinician-Observed Instruments that Measure Child Autism Spectrum Disorder

Autism spectrum disorder (ASD) diagnosis relies on parent-reported and clinician-observed instruments. Sometimes, results between these instruments disagree. The broader autism phenotype (BAP) in parent-reporters may be associated with discordance. Study to Explore Early Development data (N = 712) were used to address whether mothers with BAP and children with ASD or non-ASD developmental disabilities were more likely than mothers without BAP to 'over-' or 'under-report' child ASD on ASD screeners or interviews compared with clinician observation or overall impression. Maternal BAP was associated with a child meeting thresholds on a maternal-reported screener or maternal interview when clinician ASD instruments or impressions did not (risk ratios: 1.30 to 2.85). Evidence suggests acknowledging and accounting for reporting discordances may be important when diagnosing ASD.

Brief Report: Autism Symptoms in Infants with Fragile X Syndrome

Fragile X syndrome (FXS) is the most common known genetic cause of autism spectrum disorder (ASD). Although 50-75 % of children with FXS meet ASD criteria, no studies have compared ASD symptoms in infants with FXS versus other high risk groups, such as siblings of children with ASD (ASIBs). Using the Autism Observation Scale for Infants, our findings indicate that 53 % of 12-month infants with FXS fall in the "at risk" category compared to 17 and 6 % for age-matched ASIBs and controls, respectively. Elevated atypical motor behaviors were associated with elevated risk for FXS. Cross-syndrome comparisons are essential to understanding the heterogeneity of ASD and identifying candidate markers that will facilitate differential diagnosis of ASD in genetic disorders such as FXS.

Increased Sensory Processing Atypicalities in Parents of Multiplex ASD Families Versus Typically Developing and Simplex ASD Families

Recent studies have suggested that sensory processing atypicalities may share genetic influences with autism spectrum disorder (ASD). To further investigate this, the adolescent/adult sensory profile (AASP) questionnaire was distributed to 85 parents of typically developing children (P-TD), 121 parents from simplex ASD families (SPX), and 54 parents from multiplex ASD families (MPX). After controlling for gender and presence of mental disorders, results showed that MPX parents significantly differed from P-TD parents in all four subscales of the AASP. Differences between SPX and MPX parents reached significance in the Sensory Sensitivity subscale and also in subsequent modality-specific analyses in the auditory and visual domains. Our finding that parents with high genetic liability for ASD (i.e., MPX) had more sensory processing atypicalities than parents with low (i.e., SPX) or no (i.e., P-TD) ASD genetic liability suggests that sensory processing atypicalities may contribute to the genetic susceptibility for ASD.

Parent-reported patterns of loss and gain in communication in 1- to 2-year-old children are not unique to autism spectrum disorder

We compared loss and gain in communication from 1 to 2 years in children later diagnosed with autism spectrum disorder (n = 41), language impairment (n = 110) and in children with typical language development at 7 years (n = 831). Participants were selected from a prospective population cohort study of child language (the Early Language in Victoria Study). Parent-completed communication tools were used. As a group, children with autism spectrum disorder demonstrated slower median skill gain, with an increasing gap between trajectories compared to children with typical development and language impairment. A proportion from all groups lost skills in at least one domain (autism spectrum disorder (41%), language impairment (30%), typical development (26%)), with more children with autism spectrum disorder losing skills in more than one domain (autism spectrum disorder (47%), language impairment (15%, p = 0.0003), typical development (16%, p < 0.001)). Loss was most common for all groups in the domain of 'emotion and eye gaze' but with a higher proportion for children with autism spectrum disorder (27%; language impairment (12%, p = 0.03), typical development (14%, p = 0.03)). A higher proportion of children with autism spectrum disorder also lost skills in gesture (p = 0.01), sounds (p = 0.009) and understanding (p = 0.004) compared to children with typical development but not with language impairment. These findings add to our understanding of early communication development and highlight that loss is not unique to autism spectrum disorder.

Mothers' Parenting Behaviors in Families of School-Aged Children with Autism Spectrum Disorder: An Observational and Questionnaire Study

Although parents of children with ASD face specific challenges in parenting, only a few studies have empirically investigated parenting behaviors among these parents. The current study examined differences in parenting behaviors between mothers of school-aged children with ASD (n = 30) and mothers of typically developing children (n = 39), using both an observational measure and a self-report questionnaire. Results indicated that mothers of children with ASD obtained significantly lower scores on Sensitivity and Provision of structure as measured during the observation. They reported significantly higher scores on Material rewarding and Adapting the environment on the questionnaire. When controlling for parenting stress, the group differences on Sensitivity and Material rewarding did not remain significant.

New interview and observation measures of the broader autism phenotype: group differentiation

To identify the broader autism phenotype (BAP), the Family History Interview subject and informant versions and an observational tool (Impression of Interviewee), were developed. This study investigated whether the instruments differentiated between parents of children with autism, and parents of children with Down syndrome (DS). The BAP scores of parents of 28 multiplex autism families were compared with parents from, 32 DS families. The BAP measures provided good group differentiation but when considered together, the subject interview did not improve group differentiation. The differentiation was better for fathers than mothers. The measures do carry an important degree of validity; whether they can differentiate the BAP from other social disorders should be tested.

New Interview and Observation Measures of the Broader Autism Phenotype: Description of Strategy and Reliability Findings for the Interview Measures

Clinical genetic studies confirm the broader autism phenotype (BAP) in some relatives of individuals with autism, but there are few standardized assessment measures. We developed three BAP measures (informant interview, self-report interview, and impression of interviewee observational scale) and describe the development strategy and findings from the interviews. International Molecular Genetic Study of Autism Consortium data were collected from families containing at least two individuals with autism. Comparison of the informant and self-report interviews was restricted to samples in which the interviews were undertaken by different researchers from that site (251 UK informants, 119 from the Netherlands). Researchers produced vignettes that were rated blind by others. Retest reliability was assessed in 45 participants. Agreement between live scoring and vignette ratings was very high. Retest stability for the interviews was high. Factor analysis indicated a first factor comprising social-communication items and rigidity (but not other repetitive domain items), and a second factor comprised mainly of reading and spelling impairments. Whole scale Cronbach's alphas were high for both interviews. The correlation between interviews for factor 1 was moderate (adult items 0.50; childhood items 0.43); Kappa values for between-interview agreement on individual items were mainly low. The correlations between individual items and total score were moderate. The inclusion of several factor 2 items lowered the overall Cronbach's alpha for the total set. Both interview measures showed good reliability and substantial stability over time, but the findings were better for factor 1 than factor 2. We recommend factor 1 scores be used for characterising the BAP.

Relationship between temperament, character and the autistic trait in parents of children with autistic spectrum disorder

OBJECTIVE

Previous studies have revealed distinct features of autism, with higher harm avoidance and lower reward dependence and novelty seeking. It is assumed that high harm avoidance, and low novelty seeking, reward dependence, cooperativeness, and self-directedness are related with the broad autism phenotype, as seen in autistic individuals.

METHOD

This study examined the association between the Temperament and Character Inventory (TCI) and the Autism Spectrum Quotient (AQ), in parents of children with ASD.

RESULT

There was significant correlation between total AQ and total harm avoidance, cooperativeness, and self-directedness (p < 0.05). In the stepwise analysis, self-directedness and education emerged significantly (F(2,67) = 19.71, p < .005). This model modestly explained 35% of variance (Adjusted R(2) = .350).

CONCLUSION

Our findings suggest that self-directedness may be an autistic trait.

A review of the role of female gender in autism spectrum disorders

This paper reviews the literature exploring gender differences associated with the clinical presentation of autism spectrum disorders (ASD). The potentially mediating effect of comorbid psychopathology, biological and neurodevelopmental implications on these gender differences is also discussed. A vastly heterogeneous condition, while females on the lower-functioning end of the spectrum appear to be more severely affected, an altered clinical manifestation of the disorder among high-functioning females may consequently result in many being un- or mis-diagnosed. To date, there is strong bias in the literature towards the clinical presentation of ASD in males. It is imperative that future research explores gender differences across the autism spectrum, in order to improve researchers', clinicians' and the public's understanding of this debilitating disorder.

Subthreshold traits of the broad autistic spectrum are distributed across different subgroups in parents, but not siblings, of probands with autism

Autism is a categorical developmental disorder characterized by impairment in socialization, communication, and by restricted and circumscribed interests. Several authors have described the presence of subthreshold autistic traits in the general population, pervasive developmental disorders representing the extreme end of their distribution. In this study, we explored the presence of autistic traits in siblings and parents of a proband with autism, and in siblings and parents of a normally developing child, using the previously validated self-report French Autism Quotient, an adaptation of the AQ developed by S. Baron-Cohen. Scores were distributed between two main factors, F1 corresponding to socialization and communication, F2 to imagination and rigidity. Here, we show that both parents and siblings of a child with autism have more symptomatic scores in the domains of communication and socialization. In addition, we show that in these families the parents, but not the siblings, are distributed across different subcategories, according to their scores for the F1 and F2 domains. We hypothesize that these different subgroups may correspond to different underlying genetic mechanisms.

The broader autism phenotype in simplex and multiplex families

Mothers, fathers, and siblings from 87 multiplex (M-mothers, M-fathers, and M-siblings) and 41 simplex (S-mothers, S-fathers, and S-siblings) Autism spectrum disorder families were assessed using the Broader Phenotype Autism Symptom Scale. S-mothers, S-fathers, and S-siblings showed more social interest and were more expressive in their use of nonverbal communication compared to M-mothers, M-fathers, and M-siblings. Conversational skills were also improved in S-fathers and S-siblings compared to M-fathers and M-siblings. S-siblings showed significantly lower rigidity and intense interests compared to M-siblings. The decreased number and intensity of broader autism phenotype traits observed in parents and siblings within simplex families provide behavioral evidence consistent with findings of increased de novo genetic events in simplex families.

A molecular genetic study of autism and related phenotypes in extended pedigrees

Background

Efforts to uncover the risk genotypes associated with the familial nature of autism spectrum disorder (ASD) have had limited success. The study of extended pedigrees, incorporating additional ASD-related phenotypes into linkage analysis, offers an alternative approach to the search for inherited ASD susceptibility variants that complements traditional methods used to study the genetics of ASD.

Methods

We examined evidence for linkage in 19 extended pedigrees ascertained through ASD cases spread across at least two (and in most cases three) nuclear families. Both compound phenotypes (i.e., ASD and, in non-ASD individuals, the broad autism phenotype) and more narrowly defined components of these phenotypes, e.g., social and repetitive behavior, pragmatic language, and anxiety, were examined. The overarching goal was to maximize the aggregate information available on the maximum number of individuals and to disaggregate syndromic phenotypes in order to examine the genetic underpinnings of more narrowly defined aspects of ASD behavior.

Results

Results reveal substantial between-family locus heterogeneity and support the importance of previously reported ASD loci in inherited, familial, forms of ASD. Additional loci, not seen in the ASD analyses, show evidence for linkage to the broad autism phenotype (BAP). BAP peaks are well supported by multiple subphenotypes (including anxiety, pragmatic language, and social behavior) showing linkage to regions overlapping with the compound BAP phenotype. Whereas 'repetitive behavior’, showing the strongest evidence for linkage (Posterior Probability of Linkage = 62% at 6p25.2-24.3, and 69% at 19p13.3), appears to be linked to novel regions not detected with other compound or narrow phenotypes examined in this study.

Conclusions

These results provide support for the presence of key features underlying the complexity of the genetic architecture of ASD: substantial between-family locus heterogeneity, that the BAP appears to correspond to sets of subclinical features segregating with ASD within pedigrees, and that different features of the ASD phenotype segregate independently of one another. These findings support the additional study of larger, even more individually informative pedigrees, together with measurement of multiple, behavioral- and biomarker-based phenotypes, in both affected and non-affected individuals, to elucidate the complex genetics of familial ASD.

Parental broader autism subphenotypes in ASD affected families: relationship to gender, child's symptoms, SSRI treatment, and platelet serotonin

Relationships between parental broader autism phenotype (BAP) scores, gender, selective serotonin reuptake inhibitor (SSRI) treatment, serotonin (5HT) levels, and the child's symptoms were investigated in a family study of autism spectrum disorder (ASD). The Broader Autism Phenotype Questionnaire (BAPQ) was used to measure the BAP of 275 parents. Fathers not taking SSRIs (F-SSRI; n = 115) scored significantly higher on BAP Total and Aloof subscales compared to mothers not receiving treatment (M-SSRI; n = 136.) However, mothers taking SSRIs (M + SSRI; n = 19) scored higher than those not taking medication on BAP Total and Rigid subscales, and they were more likely to be BAPQ Total, Aloof, and Rigid positive. Significant correlations were noted between proband autism symptoms and parental BAPQ scores such that Total, Aloof, and Rigid subscale scores of F-SSRI correlated with proband restricted repetitive behavior (RRB) measures on the ADOS, CRI, and RBS-R. However, only the Aloof subscale score of M + SSRI correlated with proband RRB on the ADOS. The correlation between the BAPQ scores of mothers taking SSRIs and child scores, as well as the increase in BAPQ scores of this group of mothers, requires careful interpretation and further study because correlations would not withstand multiple corrections. As expected by previous research, significant parent-child correlations were observed for 5HT levels. However, 5HT levels were not correlated with behavioral measures. Study results suggest that the expression of the BAP varies not only across parental gender, but also across individuals using psychotropic medication and those who do not.

Quantitative autistic traits ascertained in a national survey of 22 529 Japanese schoolchildren

OBJECTIVE

Recent epidemiologic studies worldwide have documented a rise in prevalence rates for autism spectrum disorders (ASD). Broadening of diagnostic criteria for ASD may be a major contributor to the rise in prevalence, particularly if superimposed on an underlying continuous distribution of autistic traits. This study sought to determine the nature of the population distribution of autistic traits using a quantitative trait measure in a large national population sample of children.

METHOD

The Japanese version of the Social Responsiveness Scale (SRS) was completed by parents on a nationally representative sample of 22 529 children, age 6-15.

RESULTS

Social Responsiveness Scale scores exhibited a skewed normal distribution in the Japanese population with a single-factor structure and no significant relation to IQ within the normal intellectual range. There was no evidence of a natural 'cutoff' that would differentiate populations of categorically affected children from unaffected children.

CONCLUSION

This study provides evidence of the continuous nature of autistic symptoms measured by the SRS, a validated quantitative trait measure. The findings reveal how paradigms for diagnosis that rest on arbitrarily imposed categorical cutoffs can result in substantial variation in prevalence estimation, especially when measurements used for case assignment are not standardized for a given population.

Episodic memory retrieval for story characters in high-functioning autism

Background

The objective of this study was to examine differences in episodic memory retrieval between individuals with autism spectrum disorder (ASD) and typically developing (TD) individuals. Previous studies have shown that personality similarities between readers and characters facilitated reading comprehension. Highly extraverted participants read stories featuring extraverted protagonists more easily and judged the outcomes of such stories more rapidly than did less extraverted participants. Similarly, highly neurotic participants judged the outcomes of stories with neurotic protagonists more rapidly than did participants with low levels of neuroticism. However, the impact of the similarity effect on memory retrieval remains unclear. This study tested our ‘similarity hypothesis’, namely that memory retrieval is enhanced when readers with ASD and TD readers read stories featuring protagonists with ASD and with characteristics associated with TD individuals, respectively.

Methods

Eighteen Japanese individuals (one female) with high-functioning ASD (aged 17 to 40 years) and 17 age- and intelligence quotient (IQ)-matched Japanese (one female) TD participants (aged 22 to 40 years) read 24 stories; 12 stories featured protagonists with ASD characteristics, and the other 12 featured TD protagonists. Participants read a single sentence at a time and pressed a spacebar to advance to the next sentence. After reading all 24 stories, they were asked to complete a recognition task about the target sentence in each story.

Results

To investigate episodic memory in ASD, we analyzed encoding based on the reading times for and readability of the stories and retrieval processes based on the accuracy of and response times for sentence recognition. Although the results showed no differences between ASD and TD groups in encoding processes, they did reveal inter-group differences in memory retrieval. Although individuals with ASD demonstrated the same level of accuracy as did TD individuals, their patterns of memory retrieval differed with respect to response times.

Conclusions

Individuals with ASD more effectively retrieved ASD-congruent than ASD-incongruent sentences, and TD individuals retrieved stories with TD more effectively than stories with ASD protagonists. Thus, similarity between reader and story character had different effects on memory retrieval in the ASD and TD groups.

Peripheral blood gene expression signature differentiates children with autism from unaffected siblings

Autism spectrum disorder (ASD) is one of the most prevalent neurodevelopmental disorders with high heritability, yet a majority of genetic contribution to pathophysiology is not known. Siblings of individuals with ASD are at increased risk for ASD and autistic traits, but the genetic contribution for simplex families is estimated to be less when compared to multiplex families. To explore the genomic (dis-) similarity between proband and unaffected sibling in simplex families, we used genome-wide gene expression profiles of blood from 20 proband-unaffected sibling pairs and 18 unrelated control individuals. The global gene expression profiles of unaffected siblings were more similar to those from probands as they shared genetic and environmental background. A total of 189 genes were significantly differentially expressed between proband-sib pairs (nominal p < 0.01) after controlling for age, sex, and family effects. Probands and siblings were distinguished into two groups by cluster analysis with these genes. Overall, unaffected siblings were equally distant from the centroid of probands and from that of unrelated controls with the differentially expressed genes. Interestingly, five of 20 siblings had gene expression profiles that were more similar to unrelated controls than to their matched probands. In summary, we found a set of genes that distinguished probands from the unaffected siblings, and a subgroup of unaffected siblings who were more similar to probands. The pathways that characterized probands compared to siblings using peripheral blood gene expression profiles were the up-regulation of ribosomal, spliceosomal, and mitochondrial pathways, and the down-regulation of neuroreceptor-ligand, immune response and calcium signaling pathways. Further integrative study with structural genetic variations such as de novo mutations, rare variants, and copy number variations would clarify whether these transcriptomic changes are structural or environmental in origin.

Sex differences and within-family associations in the broad autism phenotype

While there is a strong sex bias in the presentation of autism, it is unknown whether this bias is also present in subclinical manifestations of autism among relatives, or the broad autism phenotype. This study examined this question and investigated patterns of co-occurrence of broad autism phenotype traits within families of individuals with autism. Pragmatic language and personality features of the broad autism phenotype were studied in 42 fathers and 50 mothers of individuals with autism using direct assessment tools used in prior family studies of the broad autism phenotype. Higher rates of aloof personality style were detected among fathers, while no sex differences were detected for other broad autism phenotype traits. Within individuals, pragmatic language features were associated with the social personality styles of the broad autism phenotype in mothers but not in fathers. A number of broad autism phenotype features were correlated within spousal pairs. Finally, the associations were detected between paternal broad autism phenotype characteristics and the severity of children's autism symptoms in all three domains (social, communication, and repetitive behaviors). Mother-child correlations were detected for aspects of communication only. Together, the findings suggest that most features of the broad autism phenotype express comparably in males and females and raise some specific questions about how such features might inform studies of the genetic basis of autism.

Common genetic variants, acting additively, are a major source of risk for autism

Background

Autism spectrum disorders (ASD) are early onset neurodevelopmental syndromes typified by impairments in reciprocal social interaction and communication, accompanied by restricted and repetitive behaviors. While rare and especially de novo genetic variation are known to affect liability, whether common genetic polymorphism plays a substantial role is an open question and the relative contribution of genes and environment is contentious. It is probable that the relative contributions of rare and common variation, as well as environment, differs between ASD families having only a single affected individual (simplex) versus multiplex families who have two or more affected individuals.

Methods

By using quantitative genetics techniques and the contrast of ASD subjects to controls, we estimate what portion of liability can be explained by additive genetic effects, known as narrow-sense heritability. We evaluate relatives of ASD subjects using the same methods to evaluate the assumptions of the additive model and partition families by simplex/multiplex status to determine how heritability changes with status.

Results

By analyzing common variation throughout the genome, we show that common genetic polymorphism exerts substantial additive genetic effects on ASD liability and that simplex/multiplex family status has an impact on the identified composition of that risk. As a fraction of the total variation in liability, the estimated narrow-sense heritability exceeds 60% for ASD individuals from multiplex families and is approximately 40% for simplex families. By analyzing parents, unaffected siblings and alleles not transmitted from parents to their affected children, we conclude that the data for simplex ASD families follow the expectation for additive models closely. The data from multiplex families deviate somewhat from an additive model, possibly due to parental assortative mating.

Conclusions

Our results, when viewed in the context of results from genome-wide association studies, demonstrate that a myriad of common variants of very small effect impacts ASD liability.

The Broad Autism Phenotype Questionnaire: mothers versus fathers of children with an autism spectrum disorder

Parents of individuals with autism were examined using the Broad Autism Phenotype Questionnaire (BAPQ; Hurley et al. in J Autism Dev Disord 37:1679-1690, 2007) assessing BAP-related personality and language characteristics. The BAPQ was administered to parents as a self-report and as an informant (spouse)-based measure. Results indicated the same pattern of differences for the informant and best-estimate (average between self-report and informant scores) reports. Fathers were rated as more "aloof" than mothers, whereas mothers were rated as more "rigid" than fathers. Fathers described their wives as less "aloof" and more "rigid" compared to the mothers' self-descriptions. Correlational analyses revealed no significant associations among parent/child characteristics and parents' BAPQ scores. Results are discussed in reference to sex differences in BAP-related characteristics in parents of children with autism.

A comparison of three self-report measures of the broader autism phenotype in a non-clinical sample

Three self-report measures of the broader autism phenotype (BAP) were evaluated in terms of their internal consistency, distribution of scores, factor structure, and criterion-related validity in a non-clinical sample. All measures showed a continuous distribution. The SRS-A and BAPQ showed expected sex differences and were superior to the AQ in terms of internal consistency. The proposed factor structure of the BAPQ replicated better than the proposed structures of the other measures. All measures showed evidence of criterion validity via correlations with related constructs and each measure incremented the others in predicting related constructs. However, the SRS-A and BAPQ were generally stronger in this domain. Recommendations for the use of these instruments for measuring the BAP in non-clinical populations are discussed.

Physiologic Arousal to Social Stress in Children with Autism Spectrum Disorders: A Pilot Study

Little is known about arousal to socially stressful situations in children with Autism Spectrum Disorders. This preliminary study investigates physiologic arousal in children with high functioning autism (HFA, n=19) compared to a comparison group (n=11) before, during, and after the Trier Social Stress Test. The HFA group was more likely to have a decrease in salivary cortisol following the stressor, while the comparison group was more likely to have an increase (p=.02). However, there was no difference in electrodermal activity, a measure of sympathetic arousal, or vagal tone, a measure of parasympathetic activity, between groups. These findings implicate a differential neuroendocrine response to social stress in children with HFA despite similar sympathetic and parasympathetic responses during a stressor. Further studies are required to substantiate this finding.

Autistic-like traits and their association with mental health problems in two nationwide twin cohorts of children and adults

BACKGROUND

Autistic-like traits (ALTs), that is restrictions in intuitive social interaction, communication and flexibility of interests and behaviors, were studied in two population-based Swedish twin studies, one in children and one in adults: (1) to examine whether the variability in ALTs is a meaningful risk factor for concomitant attention deficit hyperactivity disorder (ADHD), anxiety, conduct problems, depression and substance abuse, and (2) to assess whether common genetic and environmental susceptibilities can help to explain co-existence of ALTs and traits associated with such concomitant problems.

METHOD

Two nationwide twin cohorts from Sweden (consisting of 11 222 children and 18 349 adults) were assessed by DSM-based symptom algorithms for autism. The twins were divided into six groups based on their degree of ALTs and the risk for concomitant mental health problems was calculated for each group. Genetic and environmental susceptibilities common to ALTs and the other problem types were examined using bivariate twin modeling.

RESULTS

In both cohorts, even the lowest degree of ALTs increased the risk for all other types of mental health problems, and these risk estimates increased monotonically with the number of ALTs. For all conditions, common genetic and environmental factors could be discerned. Overall, the phenotypic correlation between ALTs and the traits examined were less pronounced in adulthood than in childhood and less affected by genetic compared with environmental factors.

CONCLUSIONS

Even low-grade ALTs are relevant to clinical psychiatry as they increase the risk for several heterotypical mental health problems. The association is influenced partly by common genetic and environmental susceptibilities. Attention to co-existing ALTs is warranted in research on a wide range of mental disorders.

Autistic traits below the clinical threshold: re-examining the broader autism phenotype in the 21st century

Diagnosis, intervention and support for people with autism can be assisted by research into the aetiology of the condition. Twin and family studies indicate that autism spectrum conditions are highly heritable; genetic relatives of people with autism often show milder expression of traits characteristic for autism, referred to as the Broader Autism Phenotype (BAP). In the past decade, advances in the biological and behavioural sciences have facilitated a more thorough examination of the BAP from multiple levels of analysis. Here, the candidate phenotypic traits delineating the BAP are summarised, including key findings from neuroimaging studies examining the neural substrates of the BAP. We conclude by reviewing the value of further research into the BAP, with an emphasis on deriving heritable endophenotypes which will reliably index autism susceptibility and offer neurodevelopmental mechanisms that bridge the gap between genes and a clinical autism diagnosis.

Quantitative autism traits in first degree relatives: evidence for the broader autism phenotype in fathers, but not in mothers and siblings

Autism spectrum disorder (ASD) symptoms are present in unaffected relatives and individuals from the general population. Results are inconclusive, however, on whether unaffected relatives have higher levels of quantitative autism traits (QAT) or not. This might be due to differences in research populations, because behavioral data and molecular genetic research suggest that the genetic etiology of ASD is different in multiplex and simplex families. We compared 117 unaffected siblings and 276 parents of at least one child with ASD with 280 children and 595 adults from the general population on the presence of QAT using the Social Responsiveness Scale (SRS). Mean SRS scores for siblings, control children, parents and control adults were 25.4, 26.6, 33.7 and 32.9. Fathers of children with ASD showed significantly higher levels of QAT than controls, but siblings and mothers did not. We could not detect a statistically significant difference in SRS scores between relatives from simplex and multiplex families. These results do not support the theory of differential (genetic) etiology in multiplex and simplex families and suggest that a carried genetic risk is generally not expressed phenotypically in most relatives, except in fathers.

Evidence for broader autism phenotype characteristics in parents from multiple-incidence autism families

The broader autism phenotype (BAP) was assessed in parents who have two or more children with autism spectrum disorder (ASD) (multiplex (MPX) autism), parents who have no more than one child with ASD (simplex autism), parents who have a child with developmental delay without ASD, and parents who have typically developing children. Clinicians, naive to parent group membership status, rated BAP characteristics from videotaped administration of the Broader Autism Phenotype Symptom Scale (BPASS). Differences among groups in BPASS scores in the four assessed domains (social motivation, conversational skills, expressiveness, and restricted interests) were examined using multivariate ANOVA and post hoc comparisons. Further, ratings of videotapes by observers naïve to family status were compared with live, non-naive ratings by observers who were aware of family status (non-naïve). Findings demonstrate that the BPASS is an instrument resistant to rater bias. Parents from MPX autism families showed significantly more autism phenotype characteristics than the parents in the other groups. Moreover, the parents from simplex autism families did not differ from the parents of children with developmental delay or typical development. Finally, no differences between live, non-naive ratings and videotaped, naive ratings were observed. These findings suggest that characteristics of the BAP, specifically in the social and communication domains, are present in MPX autism parents to a greater degree than simplex autism and control parents. Further, the results provide support for the notion that genetic transmission mechanisms may differ between families with more than one child with autism and families with only one child with autism.

The broader autism phenotype and its implications on the etiology and treatment of autism spectrum disorders

The presence of autism-related traits has been well documented in undiagnosed family members of individuals with autism spectrum disorder (ASD). The most common finding is mild impairments in social and communication skills that are similar to those shown by individuals with autism, but exhibited to a lesser degree. Termed the broader autism phenotype (BAP), these traits suggest a genetic liability for autism-related traits in families. Genetic influence in autism is strong, with identical twins showing high concordance for the diagnosis and related traits and approximately 20% of all ASD cases having an identified genetic mechanism. This paper highlights the studies conducted to date regarding the BAP and considers the implications of these findings for the etiology and treatment of ASD.

Out of the mouths of babes: vocal production in infant siblings of children with ASD

BACKGROUND

Younger siblings of children with autism spectrum disorders (ASD) are at higher risk for acquiring these disorders than the general population. Language development is usually delayed in children with ASD. The present study examines the development of pre-speech vocal behavior in infants at risk for ASD due to the presence of an older sibling with the disorder.

METHODS

Infants at high risk (HR) for ASD and those at low risk, without a diagnosed sibling (LR), were seen at 6, 9, and 12 months as part of a larger prospective study of risk for ASD in infant siblings. Standard clinical assessments were administered, and vocalization samples were collected during play with mother and a standard set of toys. Infant vocal behavior was recorded and analyzed for consonant inventory, presence of canonical syllables, and of non-speech vocalizations, in a cross-sectional design. Children were seen again at 24 months for provisional diagnosis.

RESULTS

Differences were seen between risk groups for certain vocal behaviors. Differences in vocal production in the first year of life were associated with outcomes in terms of autistic symptomotology in the second year.

CONCLUSIONS

Early vocal behavior is a sensitive indicator of heightened risk for autistic symptoms in infants with a family history of ASD.

Can family affectedness inform infant sibling outcomes of autism spectrum disorders?

BACKGROUND

Difficulties in communication and reciprocal social behavior are core features of autism spectrum disorders (ASD) and are often present, to varying degrees, in other family members. This prospective longitudinal infant sibling study examines whether social-communicative features of family members may inform which infants are at increased risk for ASD and other developmental concerns.

METHOD

Two hundred and seventeen families participated in this study. Infant siblings were recruited from families with at least one older child diagnosed with an ASD (n = 135) or at least one typically developing older child (n = 82). Families completed the Social Responsiveness Scale to assess social and communication features of the broader autism phenotype (BAP), sometimes called quantitative autistic traits (QAT). Family affectedness was assessed in two ways: categorically, based on number of affected older siblings (i.e., typical, simplex, multiplex risk groups) and dimensionally, by assessing varying degrees of QAT in all family members. Infant siblings were assessed at 36 months of age and completed the Autism Diagnostic Observation Schedule and the Mullen Scales of Early Learning.

RESULTS

In structural equation models, comparisons between multiplex, simplex and typical groups revealed the highest rates of QAT in the multiplex group followed by the simplex and typical groups. Infant sibling outcomes were predicted by gender, family risk group, proband QAT, and additional sibling QAT.

CONCLUSIONS

Replicating previous cross-sectional and family history findings, the present study found elevated social and communication features of the BAP in siblings and fathers of ASD families, but not in mothers. While social and communication features of the BAP in mothers, fathers, and undiagnosed siblings did not predict infant sibling outcomes, having more than one affected older sibling did. Infant siblings from multiplex families were at significantly higher risk for ASD than infant siblings from simplex families in this sample.

Social demographic change and autism

Parental age at child's birth--which has increased for U.S. children in the 1992-2000 birth cohorts--is strongly associated with an increased risk of autism. By turning a social demographic lens on the historical patterning of concordance among twin pairs, we identify a central mechanism for this association: de novo mutations, which are deletions, insertions, and duplications of DNA in the germ cells that are not present in the parents' DNA. Along the way, we show that a demographic eye on the rising prevalence of autism leads to three major discoveries. First, the estimated heritability of autism has been dramatically overstated. Second, heritability estimates can change over remarkably short periods of time because of increases in germ cell mutations. Third, social demographic change can yield genetic changes that, at the population level, combine to contribute to the increased prevalence of autism.

Dynamic infant-parent affect coupling during the face-to-face/still-face

We examined dynamic infant-parent affect coupling using the Face-to-Face/Still-Face (FFSF). The sample included 20 infants whose older siblings had been diagnosed with Autism Spectrum Disorders (ASD-sibs) and 18 infants with comparison siblings (COMP-sibs). A series of mixed effects bivariate autoregressive models was used to represent the self-regulation and interactive dynamics of infants and parents during the FFSF. Significant bidirectional affective coupling was found between infants and parents, with infant-to-parent coupling being more prominent than parent-to-infant coupling. Further analysis of within-dyad dynamics revealed ongoing changes in concurrent infant-parent linkages both within and between different FFSF episodes. The importance of considering both inter- and intradyad differences is discussed.

A genome-wide association study of social and non-social autistic-like traits in the general population using pooled DNA, 500 K SNP microarrays and both community and diagnosed autism replication samples

Two separate genome-wide association studies were conducted to identify single nucleotide polymorphisms (SNPs) associated with social and nonsocial autistic-like traits. We predicted that we would find SNPs associated with social and non-social autistic-like traits and that different SNPs would be associated with social and nonsocial. In Stage 1, each study screened for allele frequency differences in approximately 430,000 autosomal SNPs using pooled DNA on microarrays in high-scoring versus low-scoring boys from a general population sample (N = approximately 400/group). In Stage 2, 22 and 20 SNPs in the social and non-social studies, respectively, were tested for QTL association by individually genotyping an independent community sample of 1,400 boys. One SNP (rs11894053) was nominally associated (P < .05, uncorrected for multiple testing) with social autistic-like traits. When the sample was increased by adding females, 2 additional SNPs were nominally significant (P < .05). These 3 SNPs, however, showed no significant association in transmission disequilibrium analyses of diagnosed ASD families.

Neurodevelopmental disorders: cluster 2 of the proposed meta-structure for DSM-V and ICD-11

BACKGROUND

DSM-IV and ICD-10 are atheoretical and largely descriptive. Although this achieves good reliability, the validity of diagnoses can be increased by an understanding of risk factors and other clinical features. In an effort to group mental disorders on this basis, five clusters have been proposed. We now consider the second cluster, namely neurodevelopmental disorders.

METHOD

We reviewed the literature in relation to 11 validating criteria proposed by a DSM-V Task Force Study Group.

RESULTS

This cluster reflects disorders of neurodevelopment rather than a 'childhood' disorders cluster. It comprises disorders subcategorized in DSM-IV and ICD-10 as Mental Retardation; Learning, Motor, and Communication Disorders; and Pervasive Developmental Disorders. Although these disorders seem to be heterogeneous, they share similarities on some risk and clinical factors. There is evidence of a neurodevelopmental genetic phenotype, the disorders have an early emerging and continuing course, and all have salient cognitive symptoms. Within-cluster co-morbidity also supports grouping these disorders together. Other childhood disorders currently listed in DSM-IV share similarities with the Externalizing and Emotional clusters. These include Conduct Disorder, Attention Deficit Hyperactivity Disorder and Separation Anxiety Disorder. The Tic, Eating/Feeding and Elimination disorders, and Selective Mutisms were allocated to the 'Not Yet Assigned' group.

CONCLUSION

Neurodevelopmental disorders meet some of the salient criteria proposed by the American Psychiatric Association (APA) to suggest a classification cluster.

Language and reading abilities of children with autism spectrum disorders and specific language impairment and their first-degree relatives

Autism spectrum disorder (ASD) and specific language impairment (SLI) are developmental disorders exhibiting language deficits, but it is unclear whether they arise from similar etiologies. Language impairments have been described in family members of children with ASD and SLI, but few studies have quantified them. In this study, we examined IQ, language, and reading abilities of ASD and SLI children and their first-degree relatives to address whether the language difficulties observed in some children with ASD are familial and to better understand the degree of overlap between these disorders and their broader phenotypes. Participants were 52 autistic children, 36 children with SLI, their siblings, and their parents. The ASD group was divided into those with (ALI, n=32) and without (ALN, n=20) language impairment. Relationships between ASD severity and language performance were also examined in the ASD probands. ALI and SLI probands performed similarly on most measures while ALN probands scored higher. ALN and ALI probands' language scores were not related to Autism Diagnostic Interview-Revised and Autism Diagnostic Observation Schedule algorithm scores. SLI relatives scored lowest on all measures, and while scores were not in the impaired range, relatives of ALI children scored lower than relatives of ALN children on some measures, though not those showing highest heritability in SLI. Given that ALI relatives performed better than SLI relatives across the language measures, the hypothesis that ALI and SLI families share similar genetic loading for language is not strongly supported.

Predicting social impairment and ASD diagnosis in younger siblings of children with autism spectrum disorder

Later-born siblings of children with autism spectrum disorder (Sibs-ASD) are at elevated risk for social impairments. Two putative predictors of later social impairment-measures of responding to joint attention and weighted triadic communication-were examined in a sample of 43 Sibs-ASD who were followed from 15 to 34 months of age. Results revealed that initial level of responding to joint attention and growth rate of weighted triadic communication predicted the degree of social impairment at the final measurement period. Additionally, both predictors were associated with later ASD diagnosis. In contrast, unweighted triadic communication, age of entry into the study, and initial language level did not predict later social impairment. The importance of considering social outcome as a continuous variable in prospective studies of Sibs-ASD is discussed.