Large-scale associations between the leukocyte transcriptome and BOLD responses to speech differ in autism early language outcome subtypes.

Heterogeneity in early language development in autism spectrum disorder (ASD) is clinically important and may reflect neurobiologically distinct subtypes. Here, we identified a large-scale association between multiple coordinated blood leukocyte gene coexpression modules and the multivariate functional neuroimaging (fMRI) response to speech. Gene coexpression modules associated with the multivariate fMRI response to speech were different for all pairwise comparisons between typically developing toddlers and toddlers with ASD and poor versus good early language outcome. Associated coexpression modules were enriched in genes that are broadly expressed in the brain and many other tissues. These coexpression modules were also enriched in ASD-associated, prenatal, human-specific, and language-relevant genes. This work highlights distinctive neurobiology in ASD subtypes with different early language outcomes that is present well before such outcomes are known. Associations between neuroimaging measures and gene expression levels in blood leukocytes may offer a unique in vivo window into identifying brain-relevant molecular mechanisms in ASD

Loss of Wdfy3 in mice alters cerebral cortical neurogenesis reflecting aspects of the autism pathology.

Autism spectrum disorders (ASDs) are complex and heterogeneous developmental disabilities affecting an ever-increasing number of children worldwide. The diverse manifestations and complex, largely genetic aetiology of ASDs pose a major challenge to the identification of unifying neuropathological features. Here we describe the neurodevelopmental defects in mice that carry deleterious alleles of the Wdfy3 gene, recently recognized as causative in ASDs. Loss of Wdfy3 leads to a regionally enlarged cerebral cortex resembling early brain overgrowth described in many children on the autism spectrum. In addition, affected mouse mutants display migration defects of cortical projection neurons, a recognized cause of epilepsy, which is significantly comorbid with autism. Our analysis of affected mouse mutants defines an important role for Wdfy3 in regulating neural progenitor divisions and neural migration in the developing brain. Furthermore, Wdfy3 is essential for cerebral expansion and functional organization while its loss-of-function results in pathological changes characteristic of ASDs

Proteomic analysis of post mortem brain tissue from autism patients: Evidence for opposite changes in prefrontal cortex and cerebellum in synaptic connectivity-related proteins

BACKGROUND: Autism is a neurodevelopmental disorder characterized by impaired language, communication and social skills. Although genetic studies have been carried out in this field, none of the genes identified have led to an explanation of the underlying causes. Here, we have investigated molecular alterations by proteomic profiling of post mortem brain samples from autism patients and controls. The analysis focussed on prefrontal cortex and cerebellum as previous studies have found that these two brain regions are structurally and functionally connected, and they have been implicated in autism. METHODS: Post mortem prefrontal cortex and cerebellum samples from autism patients and matched controls were analysed using selected reaction monitoring mass spectrometry (SRM-MS). The main objective was to identify significantly altered proteins and biological pathways and to compare these across these two brain regions. RESULTS: Targeted SRM-MS resulted in identification of altered levels of proteins related to myelination, synaptic vesicle regulation and energy metabolism. This showed decreased levels of the immature astrocyte marker vimentin in both brain regions, suggesting a decrease in astrocyte precursor cells. Also, decreased levels of proteins associated with myelination and increased synaptic and energy-related proteins were found in the prefrontal cortex, indicative of increased synaptic connectivity. Finally, opposite directional changes were found for myelination and synaptic proteins in the cerebellum. CONCLUSION: These findings suggest altered structural and/or functional connectivity in the prefrontal cortex and cerebellum in autism patients, as shown by opposite effects on proteins involved in myelination and synaptic function. Further investigation of these findings could help to increase our understanding of the mechanisms underlying autism relating to brain connectivity, with the ultimate aim of facilitating novel therapeutic approaches

Investigation of the human X-linked autism protein KIDLIA in neuronal development and brain function

Previous studies of autism spectrum disorder (ASD) have shown abnormalities in brain development, synaptic plasticity, and social and learning behavior. Our previous study has identified the X-linked gene KIAA2022, and its protein product KIDLIA, as the etiological factor in a particular group of patients with intellectual disability and ASD phenotypes. I found that KIDLIA is neuron specific and localized exclusively in the nucleus, indicating a possible role for KIDLIA in neuronal gene regulation. Using rat hippocampal neurons, I found that shRNA-mediated knockdown of KIDLIA resulted in a marked impairment of neurite outgrowth via the disruption of the N-cadherin/δ-catenin/RhoA signaling pathway. Additionally, I showed that loss of KIDLIA expression decreases synapse formation and synaptic transmission. To investigate the role of KIDLIA in vivo, I generated and characterized KIDLIA knockout (KO) mice. KIDLIA KO mice demonstrated significant impairments in social interactions, increased repetitive behaviors and deficits in learning and memory, consistent with symptoms observed in human ASD patients and validate this mouse line as a valuable new model for ASD. The KIDLIA KO mice showed reduced synapse formation and abnormal expression of synaptic components such as the GluA1 subunit of AMPA receptors. To understand the potential role of KIDLIA in gene regulation, I used RNAseq to identify major candidates involved in synapse formation and function and discovered the synapse-enriched Ca2+-mediated protein, neurogranin, as the most down-regulated synaptic transcript. I showed that over-expression of neurogranin can rescue KIDLIA-dependent structural and functional synaptic deficits. This study provides valuable insight into the cellular and molecular mechanisms underlying KIDLIA-dependent autism and intellectual disability phenotypes.2018-11-08T00:00:00

Deletion of autism risk gene Shank3 disrupts prefrontal connectivity

Mutations in the synaptic scaffolding protein Shank3 are a major cause of autism, and are associated with prominent intellectual and language deficits. However, the neural mechanisms whereby SHANK3 deficiency affects higher order socio-communicative functions remain unclear. Using high-resolution functional and structural MRI in adult male mice, here we show that loss of Shank3 (Shank3B-/-) results in disrupted local and long-range prefrontal and fronto-striatal functional connectivity. We document that prefrontal hypo-connectivity is associated with reduced short-range cortical projections density, and reduced gray matter volume. Finally, we show that prefrontal disconnectivity is predictive of social communication deficits, as assessed with ultrasound vocalization recordings. Collectively, our results reveal a critical role of SHANK3 in the development of prefrontal anatomy and function, and suggest that SHANK3 deficiency may predispose to intellectual disability and socio-communicative impairments via dysregulation of higher-order cortical connectivity

Genetic implications of individual intervention and neuronal dysfunction in neurodevelopmental disorders

Neurodevelopmental disorders (NDDs) are a group of conditions appearing in childhood, with developmental deficits that produce impairments of functioning. Autism spectrum disorder (ASD) is a common NDD with a high heritability affected by complex genetic factors, including both common and rare variants. Behavior interventions such as social skills group training (SSGT) have been widely used in school-aged autistic individuals to relieve social communication difficulties in a group setting. Studies have confirmed that intervention outcomes can be influenced by sex and age, but how the genetic risk contributes to the outcome variability remains elusive. Furthermore, although large population cohorts have been well studied and have found numerous genes associated with ASD and NDDs, the molecular and neuronal outcomes of risk variants and genes are unclear. Therefore, this thesis included four studies in which the effects of genetic factors on intervention outcomes and cellular level neuronal functions were investigated. Results from this thesis may provide a genetic perspective for further studies to explore potential individualized treatments for ASD and other NDDs. Specifically, In STUDY 1-3, exome sequencing and microarray were performed on individuals from a randomized controlled trial of SSGT (KONTAKT®). Common and rare variants, including copy number variations (CNVs) and exome variants, were tested for association effects with SSGT and standard care intervention outcomes. Polygenic risk scores (PRSs) were calculated from common variants, and clinically significant rare CNVs and rare exome variants were prioritized. Molecular diagnoses were identified in 12.6% of the autistic participants. PRSs and carrier status of clinically significant rare variants were associated with intervention outcomes, although with varied effects on both SSGT and standard care. In addition, genetic scores representing variant loads in specific gene sets were obtained from rare and common variants in ASD-related pathways. Outcomes of interventions were differentially associated with genetic scores for ASD-related gene sets including synaptic transmission and transcription regulation from RNA polymerase II. After combining genetic information and behavior measures, a machine learning model was able to select important features and confirm that the intervention outcomes were predictable. In STUDY 4, genetic variants affecting Calcium/Calmodulin Dependent Serine Protein Kinase (CASK) gene, a risk gene for NDDs, were examined using human induced pluripotent stem cell-derived neuronal models to identify the cellular effects of these mutation consequences. CASK protein was reduced in maturing neurons from mutation carriers. Bulk RNA sequencing results revealed that the global expression of genes from presynaptic development and CASK network were downregulated in CASK-deficient neurons compared to controls. Neuronal cells influenced by CASK mutations showed a decrease of inhibitory presynapse size and changed excitatory-inhibitory (E/I) balance in developing neural circuitries. In summary, this is the first study to investigate the association of genome-wide rare and common variants with ASD intervention outcomes. Differential variant effects were found for individuals receiving SSGT or standard care. Future studies should include genetic information at different levels to improve molecular genetic testing for diagnoses and intervention plans. Presynapses and E/I imbalance could be an option to be developed for the treatment of CASK-related disorders

A proposal for a coordinated effort for the determination of brainwide neuroanatomical connectivity in model organisms at a mesoscopic scale

In this era of complete genomes, our knowledge of neuroanatomical circuitry remains surprisingly sparse. Such knowledge is however critical both for basic and clinical research into brain function. Here we advocate for a concerted effort to fill this gap, through systematic, experimental mapping of neural circuits at a mesoscopic scale of resolution suitable for comprehensive, brain-wide coverage, using injections of tracers or viral vectors. We detail the scientific and medical rationale and briefly review existing knowledge and experimental techniques. We define a set of desiderata, including brain-wide coverage; validated and extensible experimental techniques suitable for standardization and automation; centralized, open access data repository; compatibility with existing resources, and tractability with current informatics technology. We discuss a hypothetical but tractable plan for mouse, additional efforts for the macaque, and technique development for human. We estimate that the mouse connectivity project could be completed within five years with a comparatively modest budget.Comment: 41 page

Small semantic networks in individuals with autism spectrum disorder without intellectual impairment: A verbal fluency approach

Individuals with Autism Spectrum Disorder (ASD) experience a variety of symptoms sometimes including atypicalities in language use. The study explored diferences in semantic network organisation of adults with ASD without intellectual impairment. We assessed clusters and switches in verbal fuency tasks (‘animals’, ‘human feature’, ‘verbs’, ‘r-words’) via curve ftting in combination with corpus-driven analysis of semantic relatedness and evaluated socio-emotional and motor action related content. Compared to participants without ASD (n=39), participants with ASD (n=32) tended to produce smaller clusters, longer switches, and fewer words in semantic conditions (no p values survived Bonferroni-correction), whereas relatedness and content were similar. In ASD, semantic networks underlying cluster formation appeared comparably small without afecting strength of associations or content