Ted Hutman

Common genetic variants on 5p14.1 associate with autism spectrum disorders

Autism spectrum disorders (ASDs) represent a group of childhood neurodevelopmental and neuropsychiatric disorders characterized by deficits in verbal communication, impairment of social interaction, and restricted and repetitive patterns of interests and behaviour. To identify common genetic risk factors underlying ASDs, here we present the results of genome-wide association studies on a cohort of 780 families (3,101 subjects) with affected children, and a second cohort of 1,204 affected subjects and 6,491 control subjects, all of whom were of European ancestry. Six single nucleotide polymorphisms between cadherin 10 (CDH10) and cadherin 9 (CDH9)—two genes encoding neuronal cell-adhesion molecules—revealed strong association signals, with the most significant SNP being rs4307059 (P = 3.4u2009×u200910-8, odds ratio = 1.19). These signals were replicated in two independent cohorts, with combined Pu2009values ranging from 7.4u2009×u200910-8 to 2.1u2009×u200910-10. Our results implicate neuronal cell-adhesion molecules in the pathogenesis of ASDs, and represent, to our knowledge, the first demonstration of genome-wide significant association of common variants with susceptibility to ASDs.

Recurrence risk for autism spectrum disorders: A baby siblings research consortium study

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 infants 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.

Genome-Wide Analyses of Exonic Copy Number Variants in a Family-Based Study Point to Novel Autism Susceptibility Genes

The genetics underlying the autism spectrum disorders (ASDs) is complex and remains poorly understood. Previous work has demonstrated an important role for structural variation in a subset of cases, but has lacked the resolution necessary to move beyond detection of large regions of potential interest to identification of individual genes. To pinpoint genes likely to contribute to ASD etiology, we performed high density genotyping in 912 multiplex families from the Autism Genetics Resource Exchange (AGRE) collection and contrasted results to those obtained for 1,488 healthy controls. Through prioritization of exonic deletions (eDels), exonic duplications (eDups), and whole gene duplication events (gDups), we identified more than 150 loci harboring rare variants in multiple unrelated probands, but no controls. Importantly, 27 of these were confirmed on examination of an independent replication cohort comprised of 859 cases and an additional 1,051 controls. Rare variants at known loci, including exonic deletions at NRXN1 and whole gene duplications encompassing UBE3A and several other genes in the 15q11–q13 region, were observed in the course of these analyses. Strong support was likewise observed for previously unreported genes such as BZRAP1, an adaptor molecule known to regulate synaptic transmission, with eDels or eDups observed in twelve unrelated cases but no controls (pu200a=u200a2.3×10−5). Less is known about MDGA2, likewise observed to be case-specific (pu200a=u200a1.3×10−4). But, it is notable that the encoded protein shows an unexpectedly high similarity to Contactin 4 (BLAST E-valueu200a=u200a3×10−39), which has also been linked to disease. That hundreds of distinct rare variants were each seen only once further highlights complexity in the ASDs and points to the continued need for larger cohorts.

Beyond autism: A baby siblings research consortium study of high-risk children at three years of age

OBJECTIVEnFirst-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.nnnMETHODnTwo 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 Schedulexa0(ADOS) calibrated severity scores, and Mullen Verbal and Non-Verbal Developmental Quotients (DQ).nnnRESULTSnAt 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.nnnCONCLUSIONSnHaving 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.

Deficit, Difference, or Both? Autism and Neurodiversity

The neurodiversity movement challenges the medical models interest in causation and cure, celebrating autism as an inseparable aspect of identity. Using an online survey, we examined the perceived opposition between the medical model and the neurodiversity movement by assessing conceptions of autism and neurodiversity among people with different relations to autism. Participants (N = 657) included autistic people, relatives and friends of autistic people, and people with no specified relation to autism. Self-identification as autistic and neurodiversity awareness were associated with viewing autism as a positive identity that needs no cure, suggesting core differences between the medical model and the neurodiversity movement. Nevertheless, results suggested substantial overlap between these approaches to autism. Recognition of the negative aspects of autism and endorsement of parenting practices that celebrate and ameliorate but do not eliminate autism did not differ based on relation to autism or awareness of neurodiversity. These findings suggest a deficit-as-difference conception of autism wherein neurological conditions may represent equally valid pathways within human diversity. Potential areas of common ground in research and practice regarding autism are discussed.

Behavioral Profiles of Affected and Unaffected Siblings of Children with Autism: Contribution of Measures of Mother–Infant Interaction and Nonverbal Communication

We investigated whether deficits in social gaze and affect and in joint attention behaviors are evident within the first year of life among siblings of children with autism who go on to be diagnosed with autism or ASD (ASD) and siblings who are non-diagnosed (NoASD-sib) compared to low-risk controls. The ASD group did not differ from the other two groups at 6xa0months of age in the frequency of gaze, smiles, and vocalizations directed toward the caregiver, nor in their sensitivity to her withdrawal from interaction. However, by 12xa0months, infants in the ASD group exhibited lower rates of joint attention and requesting behaviors. In contrast, NoASD-sibs did not differ from comparison infants on any variables of interest at 6 and 12xa0months.

A Parent-Mediated Intervention to Increase Responsive Parental Behaviors and Child Communication in Children with ASD: A Randomized Clinical Trial

Longitudinal research has demonstrated that responsive parental behaviors reliably predict subsequent language gains in children with autism spectrum disorder. To investigate the underlying causal mechanisms, we conducted a randomized clinical trial of an experimental intervention (Focused Playtime Intervention, FPI) that aims to enhance responsive parental communication (Nxa0=xa070). Results showed a significant treatment effect of FPI on responsive parental behaviors. Findings also revealed a conditional effect of FPI on children’s expressive language outcomes at 12-month follow up, suggesting that children with baseline language skills below 12xa0months (nxa0=xa024) are most likely to benefit from FPI. Parents of children with more advanced language skills may require intervention strategies that go beyond FPI’s focus on responsive communication.

How Early Do Parent Concerns Predict Later Autism Diagnosis

Objective: To study the relationship between parent concerns about development in the first year and a half of life and later autism diagnostic outcomes. Method: Parent concerns about development were collected for infants at high and low risk for autism, using a prospective, longitudinal design. Parents were asked about developmental concerns at study intake and when their infant was 6, 12, and 18 months. Infants were then followed up until 36 months, when diagnostic status was determined. Results: By the time their child was 12 months, parents who have an older child with autism reported significantly more concerns in autism spectrum disorders-related areas than parents of children with typical outcomes. These concerns were significantly related to independent measures of developmental status and autism symptoms and helped predict which infants would later be diagnosed with autism or autism spectrum disorders. At 6 months, however, the concerns of parents who have an older child with autism do not predict outcome well. Conclusion: Explicitly probing for parent concerns about development is useful for identifying children in need of closer monitoring and surveillance, as recommended by the American Academy of Pediatrics.

Early Childhood Predictors of the Social Competence of Adults with Autism

Longitudinal research into adult outcomes in autism remains limited. Unlike previous longitudinal examinations of adult outcome in autism, the twenty participants in this study were evaluated across multiple assessments between early childhood (Mxa0=xa03.9xa0years) and adulthood (Mxa0=xa026.6xa0years). In early childhood, responsiveness to joint attention (RJA), language, and intelligence were assessed. In adulthood, the parents of participants responded to interviews assessing the adaptive functioning, autistic symptomology and global functioning of their children. RJA and early childhood language predicted a composite measure of adult social functioning and independence. Early childhood language skills and intelligence predicted adult adaptive behaviors. RJA predicted adult non-verbal communication, social skills and symptoms. Adaptive behaviors changed with development, but symptoms of autism did not. Additional factors associated with adult outcomes are discussed.

Imitation from 12 to 24 months in autism and typical development: A longitudinal Rasch analysis

The development of imitation during the second year of life plays an important role in domains of sociocognitive development such as language and social learning. Deficits in imitation ability in persons with autism spectrum disorder (ASD) from toddlerhood into adulthood have also been repeatedly documented, raising the possibility that early disruptions in imitation contribute to the onset of ASD and the deficits in language and social interaction that define the disorder. This study prospectively examined the development of imitation between 12 and 24 months of age in 154 infants at familial risk for ASD and 78 typically developing infants who were all later assessed at 36 months for ASD or other developmental delays. The study established a developmental measure of imitation ability and examined group differences over time, using an analytic Rasch measurement model. Results revealed a unidimensional latent construct of imitation and verified a reliable sequence of imitation skills that was invariant over time for all outcome groups. Results also showed that all groups displayed similar significant linear increases in imitation ability between 12 and 24 months and that these increases were related to individual growth in both expressive language and ratings of social engagement but not in fine motor development. The group of children who developed ASD by age 3 years exhibited delayed imitation development compared with the low-risk typical outcome group across all time-points, but were indistinguishable from other high-risk infants who showed other cognitive delays not related to ASD.