Characterization of autism in young children with tuberous sclerosis complex

Risk Factors for Psychiatric Disorders in Pediatric Patients with Tuberous Sclerosis Complex

To identify and evaluate risk factors for psychiatric disorders in pediatric patients with tuberous sclerosis complex (TSC).We recruited 121 children with TSC from the Hangzhou Children's Hospital between April 2021 and December 2023. Four clinical psychiatric scales were used to screen and diagnose the psychiatric comorbidities of TSC: the autism behavior checklist, the SNAP-IV scale, and the self-rating anxiety and depression scales. Risk factors related to each psychiatric disorder were analyzed using univariate and multivariate regression analyses.Comorbid psychiatric disorders were found in 70 (57.85%) children: 51 (42.15%) cases had autism spectrum disorder (ASD), 49 (40.50%) cases had attention-deficit hyperactivity disorder (ADHD), 17 (14.05%) cases had anxiety, and 14 (11.57%) cases had depression. Uni- and multivariate logistic regression analysis revealed that seizure frequency (>1/month; OR = 6.206, P = 0.021), use of anti-seizure medications (≥ 2 types; OR = 118.869, P = 0.003), infantile spasms (OR = 25.748, P = 0.000), ADHD (OR = 11.170, P = 0.001), and intellectual disability (OR = 32.131, P = 0.001) were risk factors for TSC children with ASD; ASD was the only risk factor for occurrence of ADHD (OR = 7.302, P = 0.022). Seizure duration (≥ 2 years; OR = 56.200, P = 0.036) and seizure frequency (>1/month; OR = 25.855, P = 0.027) were closely related to occurrence of anxiety and/or depression disorders in pediatric patients with TSC.The study results showed that psychiatric comorbidities of children with TSC had a high incidence and risk factors. The study provides new insights into the diagnosis and treatment of comorbid psychiatric disorders in pediatric patients with TSC.

Tuberous Sclerosis Complex: A Case Series from a Romanian Genetics Center and a Review of the Literature

Introduction: Tuberous sclerosis complex (TSC) is a rare multisystemic genetic disorder characterized by the formation of benign tumors in various organs, including the central nervous system, skin, kidneys, and heart. The diagnosis is based on well-defined clinical criteria, such as those from Schwartz (2007) updated in 2012 by the International Tuberous Sclerosis Complex Consensus Group. The study aims to investigate the clinical, imaging, and molecular characteristics of patients diagnosed with tuberous sclerosis and to explore the correlation between specific genetic mutations (TSC1 and TSC2 genes) and the severity of clinical manifestations. Material and Methods: This is a retrospective longitudinal study of 13 patients diagnosed with tuberous sclerosis, identified in the records of the Bihor Regional Center for Medical Genetics (BRCMG) within the Bihor County Emergency Clinical Hospital from 1984 to 2024. Clinical, imaging, and molecular features were assessed. Patients were evaluated by a multidisciplinary team, including a geneticist, pediatrician, neurologist, psychiatrist, and psychologist. Clinical and imaging data were retrospectively collected from the congenital malformations and genetic disease records of BRCMG Bihor and statistically analyzed. Results: All patients showed clinical and imaging signs consistent with the diagnosis of tuberous sclerosis. Neurological manifestations were present in 83% of patients, including epilepsy and cognitive delays. Renal lesions were detected in 46% of cases, and dermatological lesions, such as facial angiofibromas, were observed in 69% of patients. Mutational variants identified in the TSC2 gene correlated with a more severe clinical presentation, including severe intellectual disability and treatment-resistant seizures, compared to variants in the TSC1 gene. Conclusions: Our study, although involving a small number of patients, highlights the clinical heterogeneity of tuberous sclerosis and the importance of a multidisciplinary approach in patient management. Early diagnosis and ongoing monitoring are essential to improving the quality of life for patients. Further studies are needed to assess the impact of therapeutic interventions and genetic correlations within the studied population.

Tsc1 deletion in Purkinje neurons disrupts the axon initial segment, impairing excitability and cerebellar function

Loss-of-function mutations in tuberous sclerosis 1 (TSC1) are prevalent monogenic causes of autism spectrum disorder (ASD). Selective deletion of Tsc1 from mouse cerebellar Purkinje neurons has been shown to cause several ASD-linked behavioral impairments, which are linked to reduced Purkinje neuron repetitive firing rates. We used electrophysiology methods to investigate why Purkinje neuron-specific Tsc1 deletion (Tsc1mut/mut) impairs Purkinje neuron firing. These studies revealed a depolarized shift in action potential threshold voltage, an effect that we link to reduced expression of the fast-transient voltage-gated sodium (Nav) current in Tsc1mut/mut Purkinje neurons. The reduced Nav currents in these cells was associated with diminished secondary immunofluorescence from anti-pan Nav channel labeling at Purkinje neuron axon initial segments (AIS). Anti-ankyrinG immunofluorescence was also found to be significantly reduced at the AIS of Tsc1mut/mut Purkinje neurons, suggesting Tsc1 is necessary for the organization and functioning of the Purkinje neuron AIS. An analysis of the 1st and 2nd derivative of the action potential voltage-waveform supported this hypothesis, revealing spike initiation and propagation from the AIS of Tsc1mut/mut Purkinje neurons is impaired compared to age-matched control Purkinje neurons. Heterozygous Tsc1 deletion resulted in no significant changes in the firing properties of adult Purkinje neurons, and slight reductions in anti-pan Nav and anti-ankyrinG labeling at the Purkinje neuron AIS, revealing deficits in Purkinje neuron firing due to Tsc1 haploinsufficiency are delayed compared to age-matched Tsc1mut/mut Purkinje neurons. Together, these data reveal that the loss of Tsc1 impairs Purkinje neuron firing and membrane excitability through the dysregulation of proteins essential for AIS organization and function.

Tsc1 Deletion in Purkinje Neurons Disrupts the Axon Initial Segment, Impairing Excitability and Cerebellar Function

Loss-of-function mutations in tuberous sclerosis 1 (TSC1) are prevalent monogenic causes of autism spectrum disorder (ASD). Selective deletion of Tsc1 from mouse cerebellar Purkinje neurons has been shown to cause several ASD-linked behavioral impairments, which are linked to reduced Purkinje neuron repetitive firing rates. We used electrophysiology methods to investigate why Purkinje neuron-specific Tsc1 deletion (Tsc1 mut/mut ) impairs Purkinje neuron firing. These studies revealed a depolarized shift in action potential threshold voltage, an effect that we link to reduced expression of the fast-transient voltage-gated sodium (Nav) current in Tsc1 mut/mut Purkinje neurons. The reduced Nav currents in these cells was associated with diminished secondary immunofluorescence from anti-pan Nav channel labeling at Purkinje neuron axon initial segments (AIS). Interestingly, anti-ankyrinG immunofluorescence was also found to be significantly reduced at the AIS of Tsc1 mut/mut Purkinje neurons, suggesting Tsc1 is necessary for the organization and functioning of the Purkinje neuron AIS. An analysis of the 1st and 2nd derivative of the action potential voltage-waveform supported this hypothesis, revealing spike initiation and propagation from the AIS of Tsc1 mut/mut Purkinje neurons is impaired compared to age-matched control Purkinje neurons. Heterozygous Tsc1 deletion resulted in no significant changes in the firing properties of adult Purkinje neurons, and slight reductions in anti-pan Nav and anti-ankyrinG labeling at the Purkinje neuron AIS, revealing deficits in Purkinje neuron firing due to Tsc1 haploinsufficiency are delayed compared to age-matched Tsc1 mut/mut Purkinje neurons. Together, these data reveal the loss of Tsc1 impairs Purkinje neuron firing and membrane excitability through the dysregulation of proteins necessary for AIS organization and function.

Resting state EEG in young children with Tuberous Sclerosis Complex: associations with medications and seizures

BACKGROUND

Tuberous Sclerosis Complex (TSC) is a rare genetic condition caused by mutation to TSC1 or TSC2 genes, with a population prevalence of 1/7000 births. TSC manifests behaviorally with features of autism, epilepsy, and intellectual disability. Resting state electroencephalography (EEG) offers a window into neural oscillatory activity and may serve as an intermediate biomarker between gene expression and behavioral manifestations. Such a biomarker could be useful in clinical trials as an endpoint or predictor of treatment response. However, seizures and antiepileptic medications also affect resting neural oscillatory activity and could undermine the utility of resting state EEG features as biomarkers in neurodevelopmental disorders such as TSC.

METHODS

This paper compares resting state EEG features in a cross-sectional cohort of young children with TSC (n = 49, ages 12-37 months) to 49 age- and sex-matched typically developing controls. Within children with TSC, associations were examined between resting state EEG features, seizure severity composite score, and use of GABA agonists.

RESULTS

Compared to matched typically developing children, children with TSC showed significantly greater beta power in permutation cluster analyses. Children with TSC also showed significantly greater aperiodic offset (reflecting nonoscillatory neuronal firing) after power spectra were parameterized using SpecParam into aperiodic and periodic components. Within children with TSC, both greater seizure severity and use of GABAergic antiepileptic medication were significantly and independently associated with increased periodic peak beta power.

CONCLUSIONS

The elevated peak beta power observed in children with TSC compared to matched typically developing controls may be driven by both seizures and GABA agonist use. It is recommended to collect seizure and medication data alongside EEG data for clinical trials. These results highlight the challenge of using resting state EEG features as biomarkers in trials with neurodevelopmental disabilities when epilepsy and anti-epileptic medication are common.

Selective deletion of Tsc1 from mouse cerebellar Purkinje neurons drives sex-specific behavioral impairments linked to autism

There is a striking sex bias in the prevalence and severity of autism spectrum disorder (ASD) with 80% of diagnoses occurring in males. Because the molecular etiology of ASD is likely combinatorial, including interactions across multiple genetic and environmental factors, it is difficult to investigate the physiological mechanisms driving sex-specific differences. Loss of function mutations in TSC1 result in dysregulated mTORC1 signaling and underlie a multi-system disorder known as tuberous sclerosis (TSC). Interestingly, more than 50% of individuals diagnosed with TSC are also diagnosed with ASD, making TSC mutations one of the most prevalent monogenic causes of ASD. Mice harboring targeted deletion of Tsc1 selectively in cerebellar Purkinje neurons, referred to here as Tsc1mut/mut , have multiple ASD-linked behavioral impairments, including deficits in social interactions, motor coordination, and vocalizations. However, these ASD-linked behavioral deficits have only been investigated using male Tsc1mut/mut animals. Here, we used cohorts of male and female Tsc1mut/mut animals to determine if behavioral impairments, previously identified in this model, are similar across sex. Specifically, we measured balance and motor coordination and social interaction behaviors in two age groups across sex. We determined balance and motor coordination deficits are similar in male and female Tsc1mut/mut mice, and that deficits in the firing of Tsc1mut/mut Purkinje neurons located in the cerebellar vermis are also similar across sex. However, impairments in social approach behavior were found to be significantly more severe in Tsc1mut/mut males compared to females. These results indicate the selective deletion of Tsc1 in Purkinje neurons differentially impairs cerebellar circuits based on sex.

Multiparametric Assays Capture Sex- and Environment-Dependent Modifiers of Behavioral Phenotypes in Autism Mouse Models

Background

Current phenotyping approaches for murine autism models often focus on one selected behavioral feature, making the translation onto a spectrum of autistic characteristics in humans challenging. Furthermore, sex and environmental factors are rarely considered. Here, we aimed to capture the full spectrum of behavioral manifestations in 3 autism mouse models to develop a "behavioral fingerprint" that takes environmental and sex influences under consideration.

Methods

To this end, we employed a wide range of classical standardized behavioral tests and 2 multiparametric behavioral assays-the Live Mouse Tracker and Motion Sequencing-on male and female Shank2, Tsc1, and Purkinje cell-specific Tsc1 mutant mice raised in standard or enriched environments. Our aim was to integrate our high dimensional data into one single platform to classify differences in all experimental groups along dimensions with maximum discriminative power.

Results

Multiparametric behavioral assays enabled a more accurate classification of experimental groups than classical tests, and dimensionality reduction analysis demonstrated significant additional gains in classification accuracy, highlighting the presence of sex, environmental, and genotype differences in our experimental groups.

Conclusions

Together, our results provide a complete phenotypic description of all tested groups, suggesting that multiparametric assays can capture the entire spectrum of the heterogeneous phenotype in autism mouse models.

Full and Partial Facial Affect Recognition in Pediatric Brain Tumour Survivors and Typically Developing Children Following COVID-19 Pandemic

Affect recognition has emerged as a potential mechanism underlying the social competence challenges experienced by pediatric brain tumour survivors (PBTSs). However, many social interactions were altered during the pandemic, with the widespread use of masking potentially impacting affect recognition abilities. Here, we examine affect recognition in PBTSs and typically developing youth (TD) after the onset of the global pandemic. Twenty-three PBTSs and 24 TD between 8 and 16 years old were recruited and completed two performance-based affect recognition tasks (full and partial facial features) and a self-reported questionnaire on mask exposure in their social interactions. Their parents completed parent proxy questionnaires on their child's social adjustment and sociodemographics. The scores between the PBTSs and TD did not differ significantly in full (t(45) = 1.33, p = 0.19, d = 0.39, 95% CI [-0.69, 3.40]) or partial (t(37.36) = 1.56, p = 0.13, d = 0.46, 95% CI [-0.47, 3.60]) affect recognition, suggesting similar affect recognition between the two groups. These skills were also not significantly correlated with social adjustment or mask exposure (p > 0.05). However, the combined sample had significantly better scores in affect recognition when exposed to partial facial cues versus full. Additionally, participants obtained lower scores on a measure of full facial affect recognition and higher scores on a measure of partial affect recognition compared to pre-pandemic data. The pandemic may have influenced affect recognition across youth, underscoring the importance of further research into its lasting impact on the social competence of youth.

Selective deletion of Tsc1 from mouse cerebellar Purkinje neurons drives sex-specific behavioral impairments linked to autism

There is a striking sex bias in the prevalence and severity of autism spectrum disorder (ASD) with 80% of diagnoses occurring in males. Because the molecular etiology of ASD is likely combinatorial, including interactions across multiple genetic and environmental factors, it is difficult to investigate the physiological mechanisms driving sex-specific differences. Loss of function mutations in TSC1 result in dysregulated mTORC1 signaling and underlie a multi-system disorder known as tuberous sclerosis (TSC). Interestingly, more than 50% of individuals diagnosed with TSC are also diagnosed with ASD, making TSC mutations one of the most prevalent monogenic causes of ASD. Mice harboring targeted deletion of Tsc1 selectively in cerebellar Purkinje neurons, referred to here as Tsc1 mut/mut , have multiple ASD-linked behavioral impairments, including deficits in social interactions, motor coordination, and vocalizations. However, these ASD-linked behavioral deficits have only been investigated using male Tsc1 mut/mut animals. Here, we used cohorts of male and female Tsc1 mut/mut animals to determine if behavioral impairments, previously identified in this model, are similar across sex. Specifically, we measured balance and motor coordination and social interaction behaviors in two age groups across sex. W e determined balance and motor coordination deficits are similar in male and female Tsc1 mut/mut mice, and that deficits in the firing of Tsc1 mut/mut Purkinje neurons located in the cerebellar vermis are also similar across sex. However, impairments in social approach behavior were found to be significantly more severe in Tsc1 mut/mut males compared to females. These results indicate the selective deletion of Tsc1 in Purkinje neurons differentially impairs cerebellar circuits based on sex.

Social and Emotional Functioning of Pediatric Brain Tumor Survivors and Typically Developing Youth Following the Onset of the Pandemic

Background: Social competence is a domain in which pediatric brain tumour survivors (PBTS) are at risk of challenges. To follow-up on our earlier work, in this study we assessed specific social interaction behaviors and emotional functioning in PBTS relative to typically developing youth (TD). The study coincided with the onset of the global pandemic. Methods: Sixteen PBTS and 16 typically developing youth (TD) between 8-16 years old participated in the study. Youth completed an assessment of social behavior and parents completed online surveys regarding child social and emotional adjustment. Results: PBTS experienced greater impairments in social interaction behaviors and on indices of social adjustment relative to TD. PBTS and TD experienced similar levels of emotional problems. Social behavior challenges were associated with indices of anxiety, rather than depression. Time since pandemic onset was not associated with social emotional outcomes. Conclusions: It will be important to monitor and support the social adjustment of populations such as PBTS, as well as the emotional adjustment across PBTS and TD youth, following the pandemic.

Abnormality of Early White Matter Development in Tuberous Sclerosis Complex and Autism Spectrum Disorder: Longitudinal Analysis of Diffusion Tensor Imaging Measures

Background: Abnormalities in white matter development may influence development of autism spectrum disorder in tuberous sclerosis complex (TSC). Our goals for this study were as follows: (1) use data from a longitudinal neuroimaging study of tuberous sclerosis complex (TACERN) to develop optimized linear mixed effects models for analyzing longitudinal, repeated diffusion tensor imaging metrics (fractional anisotropy, mean diffusivity) pertaining to select white matter tracts, in relation to positive Autism Diagnostic Observation Schedule-Second Edition classification at 36 months, and (2) perform an exploratory analysis using optimized models applied to all white matter tracts from these data. Methods: Eligible participants (3-12 months) underwent brain magnetic resonance imaging (MRI) at repeated time points from ages 3 to 36 months. Positive Autism Diagnostic Observation Schedule-Second Edition classification at 36 months was used. Linear mixed effects models were fine-tuned separately for fractional anisotropy values (using fractional anisotropy corpus callosum as test outcome) and mean diffusivity values (using mean diffusivity right posterior limb internal capsule as test outcome). Fixed effects included participant age, within-participant longitudinal age, and autism spectrum disorder diagnosis. Results: Analysis included data from n = 78. After selecting separate optimal models for fractional anisotropy and mean diffusivity values, we applied these models to fractional anisotropy and mean diffusivity of all 27 white matter tracts. Fractional anisotropy corpus callosum was related to positive Autism Diagnostic Observation Schedule-Second Edition classification (coefficient = 0.0093, P = .0612), and mean diffusivity right inferior cerebellar peduncle was related to positive Autism Diagnostic Observation Schedule-Second Edition classification (coefficient = -0.00002071, P = .0445), though these findings were not statistically significant after multiple comparisons correction. Conclusion: These optimized linear mixed effects models possibly implicate corpus callosum and cerebellar pathology in development of autism spectrum disorder in tuberous sclerosis complex, but future studies are needed to replicate these findings and explore contributors of heterogeneity in these models.

The autism susceptibility kinase, TAOK2, phosphorylates eEF2 and modulates translation

Genes implicated in translation control have been associated with autism spectrum disorders (ASDs). However, some important genetic causes of autism, including the 16p11.2 microdeletion, bear no obvious connection to translation. Here, we use proteomics, genetics, and translation assays in cultured cells and mouse brain to reveal altered translation mediated by loss of the kinase TAOK2 in 16p11.2 deletion models. We show that TAOK2 associates with the translational machinery and functions as a translational brake by phosphorylating eukaryotic elongation factor 2 (eEF2). Previously, all signal-mediated regulation of translation elongation via eEF2 phosphorylation was believed to be mediated by a single kinase, eEF2K. However, we show that TAOK2 can directly phosphorylate eEF2 on the same regulatory site, but functions independently of eEF2K signaling. Collectively, our results reveal an eEF2K-independent signaling pathway for control of translation elongation and suggest altered translation as a molecular component in the etiology of some forms of ASD.

Autism and Epilepsy

Epilepsy is one of the most common comorbidities in individuals with autism spectrum disorders (ASDs). Risk factors include the presence of developmental delay/intellectual disability, female sex, age, and an underlying genetic condition. Due to higher prevalence of epilepsy in ASD, it is important to have a high index of suspicion for seizures and refer to a neurologist if there are concerns. Genetic testing is recommended for all children with ASD but it becomes more high yield in children with epilepsy and ASD.

Is tuberous sclerosis complex-associated autism a preventable and treatable disorder?

BACKGROUND

Tuberous sclerosis complex (TSC) is a genetic disorder caused by inactivating mutations in the TSC1 and TSC2 genes, causing overactivation of the mechanistic (previously referred to as mammalian) target of rapamycin (mTOR) signaling pathway in fetal life. The mTOR pathway plays a crucial role in several brain processes leading to TSC-related epilepsy, intellectual disability, and autism spectrum disorder (ASD). Pre-natal or early post-natal diagnosis of TSC is now possible in a growing number of pre-symptomatic infants.

DATA SOURCES

We searched PubMed for peer-reviewed publications published between January 2010 and April 2023 with the terms "tuberous sclerosis", "autism", or "autism spectrum disorder"," animal models", "preclinical studies", "neurobiology", and "treatment".

RESULTS

Prospective studies have highlighted that developmental trajectories in TSC infants who were later diagnosed with ASD already show motor, visual and social communication skills in the first year of life delays. Reliable genetic, cellular, electroencephalography and magnetic resonance imaging biomarkers can identify pre-symptomatic TSC infants at high risk for having autism and epilepsy.

CONCLUSIONS

Preventing epilepsy or improving therapy for seizures associated with prompt and tailored treatment strategies for autism in a sensitive developmental time window could have the potential to mitigate autistic symptoms in infants with TSC.

Diversity and Classification of Genetic Variations in Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a neurodevelopmental condition with symptoms that affect the whole personality and all aspects of life. Although there is a high degree of heterogeneity in both its etiology and its characteristic behavioral patterns, the disorder is well-captured along the autistic triad. Currently, ASD status can be confirmed following an assessment of behavioral features, but there is a growing emphasis on conceptualizing autism as a spectrum, which allows for establishing a diagnosis based on the level of support need, free of discrete categories. Since ASD has a high genetic predominance, the number of genetic variations identified in the background of the condition is increasing exponentially as genetic testing methods are rapidly evolving. However, due to the huge amount of data to be analyzed, grouping the different DNA variations is still challenging. Therefore, in the present review, a multidimensional classification scheme was developed to accommodate most of the currently known genetic variants associated with autism. Genetic variations have been grouped according to six criteria (extent, time of onset, information content, frequency, number of genes involved, inheritance pattern), which are themselves not discrete categories, but form a coherent continuum in line with the autism spectrum approach.

Understanding speech and language in tuberous sclerosis complex

Tuberous Sclerosis Complex (TSC), is a neurocutaneous disorder, associated with a high prevalence of autism spectrum disorder (ASD; ∼50% of individuals). As TSC is a leading cause of syndromic ASD, understanding language development in this population would not only be important for individuals with TSC but may also have implications for those with other causes of syndromic and idiopathic ASD. In this mini review, we consider what is known about language development in this population and how speech and language in TSC are related to ASD. Although up to 70% of individuals with TSC report language difficulties, much of the limited research to date on language in TSC has been based on summary scores from standardized assessments. Missing is a detailed understanding of the mechanisms driving speech and language in TSC and how they relate to ASD. Here, we review recent work suggesting that canonical babbling and volubility-two precursors of language development that predict the emergence of speech and are delayed in infants with idiopathic ASD-are also delayed in infants with TSC. We then look to the broader literature on language development to identify other early precursors of language development that tend to be delayed in children with autism as a guide for future research on speech and language in TSC. We argue that vocal turn-taking, shared attention, and fast mapping are three such skills that can provide important information about how speech and language develop in TSC and where potential delays come from. The overall goal of this line of research is to not only illuminate the trajectory of language in TSC with and without ASD, but to ultimately find strategies for earlier recognition and treatment of the pervasive language difficulties in this population.

Heterogeneity of Autism Characteristics in Genetic Syndromes: Key Considerations for Assessment and Support

Purpose of Review

Elevated prevalence of autism characteristics is reported in genetic syndromes associated with intellectual disability. This review summarises recent evidence on the behavioural heterogeneity of autism in the following syndromes: Fragile X, Cornelia de Lange, Williams, Prader-Willi, Angelman, Down, Smith-Magenis, and tuberous sclerosis complex. Key considerations for assessment and support are discussed.

Recent Findings

The profile and developmental trajectory of autism-related behaviour in these syndromes indicate some degree of syndrome specificity which may interact with broader behavioural phenotypes (e.g. hypersociability), intellectual disability, and mental health (e.g. anxiety). Genetic subtype and co-occurring epilepsy within syndromes contribute to increased significance of autism characteristics. Autism-related strengths and challenges are likely to be overlooked or misunderstood using existing screening/diagnostic tools and criteria, which lack sensitivity and specificity within these populations.

Summary

Autism characteristics are highly heterogeneous across genetic syndromes and often distinguishable from non-syndromic autism. Autism diagnostic assessment practices in this population should be tailored to specific syndromes. Service provisions must begin to prioritise needs-led support.

Gene Therapy for Neuropsychiatric Disorders: Potential Targets and Tools

Neuropsychiatric disorders that affect the central nervous system cause considerable pressures on the health care system and have a substantial economic burden on modern societies. The present treatments based on available drugs are mostly ineffective and often costly. The molecular process of neuropsychiatric disorders is closely connected to modifying the genetic structures inherited or caused by damage, toxic chemicals, and some current diseases. Gene therapy is presently an experimental concept for neurological disorders. Clinical applications endeavor to alleviate the symptoms, reduce disease progression, and repair defective genes. Implementing gene therapy in inherited and acquired neurological illnesses entails the integration of several scientific disciplines, including virology, neurology, neurosurgery, molecular genetics, and immunology. Genetic manipulation has the power to minimize or cure illness by inducing genetic alterations at endogenous loci. Gene therapy that involves treating the disease by deleting, silencing, or editing defective genes and delivering genetic material to produce therapeutic molecules has excellent potential as a novel approach for treating neuropsychiatric disorders. With the recent advances in gene selection and vector design quality in targeted treatments, gene therapy could be an effective approach. This review article will investigate and report the newest and the most critical molecules and factors in neuropsychiatric disorder gene therapy. Different genome editing techniques available will be evaluated, and the review will highlight preclinical research of genome editing for neuropsychiatric disorders while also evaluating current limitations and potential strategies to overcome genome editing advancements.

The autism spectrum disorder phenotype in children with tuberous sclerosis complex: A systematic review and meta-analysis

AIM

To investigate the phenotype in autistic children with tuberous sclerosis complex (TSC), specifically autism spectrum disorder (ASD) severity and characteristics, intellectual ability, adaptive and executive function, language skills, attention-deficit/hyperactivity disorder features, and internalizing and externalizing behaviours.

METHOD

MEDLINE, Embase, and the Cochrane Library were searched up to March 2021. Studies that investigated predefined phenotypic factors in children with TSC-ASD were included according to the Preferred Reporting Items for Systematic review and Meta-Analysis Protocols (PRISMA-P) guidelines. Two authors independently reviewed titles, abstracts, full texts, and extracted the data. Risk of bias and GRADE assessments were completed.

RESULTS

Thirty-four studies with 3160 children with TSC, 30% with ASD, were included. Meta-analysis found that 90% (95% confidence interval 86%-94%) of children with TSC-ASD have an intellectual disability. There was some evidence to suggest that young children with TSC-ASD and idiopathic ASD have a similar pattern of severity and behaviour. Overall, data about phenotypic characteristics were limited.

INTERPRETATION

A greater proportion of children with TSC-ASD are reported to have an intellectual disability than children with idiopathic ASD. Early intervention should consider the needs of children with a high likelihood of intellectual disability. Research is needed to better understand the impacts of intellectual disability and other co-occurring difficulties on adaptive function, participation, and quality of life in TSC-ASD.

WHAT THIS PAPER ADDS

Most children with tuberous sclerosis complex (TSC) and autism spectrum disorder (ASD) have an intellectual disability. TSC-ASD early intervention planning should consider the high likelihood of intellectual disability. Quality of life and the functional impact of intellectual disability in TSC-ASD are not understood. Little is known about co-occurring difficulties in TSC-ASD.

The Cerebellar Gene Database: a Collective Database of Genes Critical for Cerebellar Development

This report presents the first comprehensive database that specifically compiles genes critical for cerebellar development and function. The Cerebellar Gene Database details genes that, when perturbed in mouse models, result in a cerebellar phenotype according to available data from both Mouse Genome Informatics and PubMed, as well as references to the corresponding studies for further examination. This database also offers a compilation of human genetic disorders with a cerebellar phenotype and their associated gene information from the Online Mendelian Inheritance in Man (OMIM) database. By comparing and contrasting the mouse and human datasets, we observe that only a small proportion of human mutant genes with a cerebellar phenotype have been studied in mouse knockout models. Given the highly conserved nature between mouse and human genomes, this surprising finding highlights how mouse genetic models can be more frequently employed to elucidate human disease etiology. On the other hand, many mouse genes identified in the present study that are known to lead to a cerebellar phenotype when perturbed have not yet been found to be pathogenic in the cerebellum of humans. This database furthers our understanding of human cerebellar disorders with yet-to-be-identified genetic causes. It is our hope that this gene database will serve as an invaluable tool for gathering background information, generating hypotheses, and facilitating translational research endeavors. Moreover, we encourage continual inputs from the research community in making this compilation a living database, one that remains up-to-date with the advances in cerebellar research.

The Cerebellar Involvement in Autism Spectrum Disorders: From the Social Brain to Mouse Models

Autism spectrum disorders (ASD) are pervasive neurodevelopmental disorders that include a variety of forms and clinical phenotypes. This heterogeneity complicates the clinical and experimental approaches to ASD etiology and pathophysiology. To date, a unifying theory of these diseases is still missing. Nevertheless, the intense work of researchers and clinicians in the last decades has identified some ASD hallmarks and the primary brain areas involved. Not surprisingly, the areas that are part of the so-called “social brain”, and those strictly connected to them, were found to be crucial, such as the prefrontal cortex, amygdala, hippocampus, limbic system, and dopaminergic pathways. With the recent acknowledgment of the cerebellar contribution to cognitive functions and the social brain, its involvement in ASD has become unmistakable, though its extent is still to be elucidated. In most cases, significant advances were made possible by recent technological developments in structural/functional assessment of the human brain and by using mouse models of ASD. Mouse models are an invaluable tool to get insights into the molecular and cellular counterparts of the disease, acting on the specific genetic background generating ASD-like phenotype. Given the multifaceted nature of ASD and related studies, it is often difficult to navigate the literature and limit the huge content to specific questions. This review fulfills the need for an organized, clear, and state-of-the-art perspective on cerebellar involvement in ASD, from its connections to the social brain areas (which are the primary sites of ASD impairments) to the use of monogenic mouse models.

Pediatric Brain Tumor Survivors' Understanding of Friendships: A Qualitative Analysis of ADOS-2 Interview Responses

BACKGROUND

Pediatric brain tumor survivors (PBTS) are at risk of experiencing social competence challenges, but only a limited number of studies have used a qualitative approach to understand their social relationships. We examined PBTS responses to social interview questions within the Autism Diagnostic Observation Schedule, 2nd edition (ADOS-2), which includes questions related to their understanding of their own relationships, as well as the construct of friendship more generally.

METHODS

Twenty-four PBTS (ages 9-17 years; M = 14.2 years from diagnosis; 50% male; 42% received radiation treatment) completed the ADOS-2. ADOS-2 social interview responses were recorded and transcribed verbatim. Themes were derived using an inductive thematic analysis approach.

RESULTS

PBTS reported that they considered trust, acceptance, respect, emotional support, and spending time together to be important aspects of friendships in general. When describing their own social relationships, some PBTS noted a lack of intimacy or closeness, spending time with their friends almost exclusively at school, with structured activities outside of school being an additional basis for friendship. Challenges to their social relationships included loneliness and reliance on family for social support, experiences of teasing and bullying, social skills deficits, and lack of insight into social situations.

CONCLUSION

Although PBTS were able to acknowledge many important qualities of friendships in general (e.g., trust, emotional support), these were not necessarily reported in their own friendships. PBTS also appeared to have difficulty identifying whether someone was their friend. These findings offer potential opportunities for supporting PBTS in achieving friendships consistent with their conception of this important relationship.

Harnessing rare variants in neuropsychiatric and neurodevelopment disorders-a Keystone Symposia report

Neurodevelopmental neuropsychiatric disorders, such as autism spectrum disorder and schizophrenia, have strong genetic risk components, but the underlying mechanisms have proven difficult to decipher. Rare, high-risk variants may offer an opportunity to delineate the biological mechanisms responsible more clearly for more common idiopathic diseases. Indeed, different rare variants can cause the same behavioral phenotype, demonstrating genetic heterogeneity, while the same rare variant can cause different behavioral phenotypes, demonstrating variable expressivity. These observations suggest convergent underlying biological and neurological mechanisms; identification of these mechanisms may ultimately reveal new therapeutic targets. At the 2021 Keystone eSymposium "Neuropsychiatric and Neurodevelopmental Disorders: Harnessing Rare Variants" a panel of experts in the field described significant progress in genomic discovery and human phenotyping and raised several consistent issues, including the need for detailed natural history studies of rare disorders, the challenges in cohort recruitment, and the importance of viewing phenotypes as quantitative traits that are impacted by rare variants.

Altered nociceptive behavior and emotional contagion of pain in mouse models of autism

Individuals with autism spectrum disorder (ASD) have altered sensory processing but may ineffectively communicate their experiences. Here, we used a battery of nociceptive behavioral tests to assess sensory alterations in two commonly used mouse models of ASD, BTBR T⁺ Itpr3^tf /J (BTBR), and fragile-X mental retardation-1 knockout (Fmr1-KO) mice. We also asked whether emotional contagion, a primitive form of empathy, was altered in BTBR and Fmr1 KO mice when experiencing pain with a social partner. BTBR mice demonstrated mixed nociceptive responses with hyporesponsivity to mechanical/thermal stimuli and intraplantar injections of formalin and capsaicin while displaying hypersensitivity on the acetic acid test. Fmr1-KO mice were hyposensitive to mechanical stimuli and intraplantar injections of capsaicin and formalin. BTBR and Fmr1-KO mice developed significantly less mechanical allodynia following intraplantar injections of complete Freund's adjuvant, while BTBR mice developed slightly more thermal hyperalgesia. Finally, as measured by the formalin and acetic acid writhing tests, BTBR and Fmr1-KO mice did not show emotional contagion of pain. In sum, our findings indicate that depending on the sensation, pain responses may be mixed, which reflects findings in ASD individuals.

Characterising the Early Presentation of Motor Difficulties in Autistic Children

This study aimed to explore the rates of motor difficulties in children from the Australian Autism Biobank, and how early motor concerns impacted on children functionally. Children with autism aged 2-7 years, including 441 with a Vineland Adaptive Behavior Scale (VABS-II) motor subscale and 385 with a Mullen Scales of Early Learning (MSEL) fine motor subscale were included (n total = 514; 80% male). Approximately 60% of children on the MSEL and ~ 25% on the VABS-II had clinically significant motor impairments. More children with delayed sitting and walking motor milestones had early childhood parent reported motor difficulties (p < 0.001). Early motor delays or concerns may assist identifying individuals who will likely benefit from early ongoing developmental monitoring and early support.

Profile of Autism Spectrum Disorder in Tuberous Sclerosis Complex: Results from a Longitudinal, Prospective, Multisite Study

OBJECTIVE

Tuberous sclerosis complex (TSC) is highly associated with autism spectrum disorder (ASD). Objectives of the study were to characterize autistic features in young children with TSC.

METHODS

Participants included 138 children followed from ages 3 to 36 months with TSC from the Tuberous Sclerosis Complex Autism Center of Excellence Research Network (TACERN), a multicenter, prospective observational study aimed at understanding the underlying mechanisms of ASD in TSC. Developmental and autism-specific assessments were administered, and a clinical diagnosis of ASD was determined for all participants at 36 months. Further analyses were performed on 117 participants with valid autism assessments based on nonverbal mental age greater than 15 months.

RESULTS

Prevalence of clinical diagnosis of ASD at 36 months was 25%. Nearly all autistic behaviors on the Autism Diagnostic Observation Schedule-2 (ADOS-2) and Autism Diagnostic Interview-Revised (ADI-R) were more prevalent in children diagnosed with ASD; however, autism-specific behaviors were also observed in children without ASD. Overall quality of social overtures, facial expressions, and abnormal repetitive interests and behaviors were characteristics most likely to distinguish children with ASD from those without an ASD diagnosis. Participants meeting ADOS-2 criteria but not a clinical ASD diagnosis exhibited intermediate developmental and ADOS-2 scores compared to individuals with and without ASD.

INTERPRETATION

ASD is highly prevalent in TSC, and many additional individuals with TSC exhibit a broad range of subthreshold autistic behaviors. Our findings reveal a broader autism phenotype that can be identified in young children with TSC, which provides opportunity for early targeted treatments. ANN NEUROL 2021.

Neuropsychological and ASD phenotypes in rare genetic syndromes: A critical review of the literature

OBJECTIVE

Autism spectrum disorder (ASD) is a complex neurodevelopmental condition characterized by core deficits in social communication and restricted and repetitive behaviors and interests. Recent advances in clinical genetics have improved our understanding of genetic syndromes associated with ASD, which has helped clarify distinct etiologies of ASD and document syndrome-specific profiles of neurocognitive strengths and weaknesses. Pediatric neuropsychologists have the potential to be impactful members of the care team for children with genetic syndromes and their families.

METHOD

We provide a critical review of the current literature related to the neuropsychological profiles of children with four genetic syndromes associated with ASD, including Tuberous Sclerosis Complex (TSC), fragile X syndrome (FXS), 22q11.2 deletion syndrome, and Angelman syndrome. Recommendations for assessment, intervention, and future directions are provided.

RESULTS

There is vast heterogeneity in terms of the cognitive, language, and developmental abilities of these populations. The within- and across-syndrome variability characteristic of genetic syndromes should be carefully considered during clinical evaluations, including possible measurement limitations, presence of intellectual disability, and important qualitative differences in the ASD-phenotypes across groups.

CONCLUSIONS

Individuals with genetic disorders pose challenging diagnostic and assessment questions. Pediatric neuropsychologists with expertise in neurodevelopmental processes are well suited to address these questions and identify profiles of neurocognitive strengths and weaknesses, tailor individualized recommendations, and provide diagnostic clarification.

Synaptic Alterations in a Transgenic Model of Tuberous Sclerosis Complex: Relevance to Autism Spectrum Disorders

Tuberous sclerosis complex (TSC) is a rare, multi-system genetic disease with serious neurological and mental symptoms, including autism. Mutations in the TSC1/TSC2 genes lead to the overactivation of mTOR signalling, which is also linked to nonsyndromic autism. Our aim was to analyse synaptic pathology in a transgenic model of TSC: two-month-old male B6;129S4-Tsc2^tm1Djk/J mice with Tsc2 haploinsufficiency. Significant brain-region-dependent alterations in the expression of several synaptic proteins were identified. The most prominent changes were observed in the immunoreactivity of presynaptic VAMP1/2 (ca. 50% increase) and phospho-synapsin-1 (Ser62/67) (ca. 80% increase). Transmission electron microscopy demonstrated serious ultrastructural abnormalities in synapses such as a blurred structure of synaptic density and a significantly increased number of synaptic vesicles. The impairment of synaptic mitochondrial ultrastructure was represented by excessive elongation, swelling, and blurred crista contours. Polyribosomes in the cytoplasm and swollen Golgi apparatus suggest possible impairment of protein metabolism. Moreover, the delamination of myelin and the presence of vacuolar structures in the cell nucleus were observed. We also report that Tsc2^+/- mice displayed increased brain weights and sizes. The behavioural analysis demonstrated the impairment of memory function, as established in the novel object recognition test. To summarise, our data indicate serious synaptic impairment in the brains of male Tsc2^+/- mice.

The Connectivity Fingerprint of the Fusiform Gyrus Captures the Risk of Developing Autism in Infants with Tuberous Sclerosis Complex

Tuberous sclerosis complex (TSC) is a rare genetic disorder characterized by benign tumors throughout the body; it is generally diagnosed early in life and has a high prevalence of autism spectrum disorder (ASD), making it uniquely valuable in studying the early development of autism, before neuropsychiatric symptoms become apparent. One well-documented deficit in ASD is an impairment in face processing. In this work, we assessed whether anatomical connectivity patterns of the fusiform gyrus, a central structure in face processing, capture the risk of developing autism early in life. We longitudinally imaged TSC patients at 1, 2, and 3 years of age with diffusion compartment imaging. We evaluated whether the anatomical connectivity fingerprint of the fusiform gyrus was associated with the risk of developing autism measured by the Autism Observation Scale for Infants (AOSI). Our findings suggest that the fusiform gyrus connectivity captures the risk of developing autism as early as 1 year of age and provides evidence that abnormal fusiform gyrus connectivity increases with age. Moreover, the identified connections that best capture the risk of developing autism involved the fusiform gyrus and limbic and paralimbic regions that were consistent with the ASD phenotype, involving an increased number of left-lateralized structures with increasing age.

Loss of Tsc1 in cerebellar Purkinje cells induces transcriptional and translation changes in FMRP target transcripts

Tuberous sclerosis complex (TSC) is a genetic disorder that is associated with multiple neurological manifestations. Previously, we demonstrated that Tsc1 loss in cerebellar Purkinje cells (PCs) can cause altered social behavior in mice. Here, we performed detailed transcriptional and translational analyses of Tsc1-deficient PCs to understand the molecular alterations in these cells. We found that target transcripts of the Fragile X Mental Retardation Protein (FMRP) are reduced in mutant PCs with evidence of increased degradation. Surprisingly, we observed unchanged ribosomal binding for many of these genes using translating ribosome affinity purification. Finally, we found that multiple FMRP targets, including SHANK2, were reduced, suggesting that compensatory increases in ribosomal binding efficiency may be unable to overcome reduced transcript levels. These data further implicate dysfunction of FMRP and its targets in TSC and suggest that treatments aimed at restoring the function of these pathways may be beneficial.

Microbiota and Microglia Interactions in ASD

Autism spectrum disorders (ASD) are serious, highly variable neurodevelopmental disorders, commonly characterized by the manifestation of specific behavioral abnormalities, such as stereotypic behaviors and deficits in social skills, including communication. Although the neurobiological basis for ASD has attracted attention in recent decades, the role of microglial cells, which are the main resident myeloid cell population in the brain, is still controversial and underexplored. Microglia play several fundamental roles in orchestrating brain development and homeostasis. As such, alterations in the intrinsic functions of these cells could be one of the driving forces responsible for the development of various neurodevelopmental disorders, including ASD. Microglia are highly sensitive to environmental cues. Amongst the environmental factors known to influence their intrinsic functions, the gut microbiota has emerged as a central player, controlling both microglial maturation and activation. Strikingly, there is now compelling data suggesting that the intestinal microbiota can play a causative role in driving the behavioural changes associated with ASD. Not only is intestinal dysbiosis commonly reported in ASD patients, but therapies targeting the microbiome can markedly alleviate behavioral symptoms. Here we explore the emerging mechanisms by which altered microglial functions could contribute to several major etiological factors of ASD. We then demonstrate how pre- and postnatal environmental stimuli can modulate microglial cell phenotype and function, underpinning the notion that reciprocal interactions between microglia and intestinal microbes could play a crucial role in ASD aetiology.

mTOR inhibitor improves autistic-like behaviors related to Tsc2 haploinsufficiency but not following developmental status epilepticus

Background

Tuberous sclerosis complex (TSC), a multi-system genetic disorder often associated with autism spectrum disorder (ASD), is caused by mutations of TSC1 or TSC2, which lead to constitutive overactivation of mammalian target of rapamycin (mTOR). In several Tsc1+/- and Tsc2+/- animal models, cognitive and social behavior deficits were reversed by mTOR inhibitors. However, phase II studies have not shown amelioration of ASD and cognitive deficits in individuals with TSC during mTOR inhibitor therapy. We asked here if developmental epilepsy, common in the majority of individuals with TSC but absent in most animal models, could explain the discrepancy.

Methods

At postnatal day P12, developmental status epilepticus (DSE) was induced in male Tsc2+/- (Eker) and wild-type rats, establishing four experimental groups including controls. In adult animals (n = 36), the behavior was assessed in the paradigms of social interaction test, elevated plus-maze, light-dark test, Y-maze, and novel object recognition. The testing was carried out before medication (T1), during a 2-week treatment with the mTOR inhibitor everolimus (T2) and after an 8-week washing-out (T3). Electroencephalographic (EEG) activity was recorded in a separate set of animals (n = 18).

Results

Both Tsc2+/- mutation and DSE caused social behavior deficits and epileptiform EEG abnormalities (T1). Everolimus led to a persistent improvement of the social deficit induced by Tsc2+/-, while deficits related to DSE did not respond to everolimus (T2, T3).

Conclusions

These findings may contribute to an explanation why ASD symptoms in individuals with TSC, where comorbid early-onset epilepsy is common, were not reliably ameliorated by mTOR inhibitors in clinical studies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s11689-021-09357-2.

A Novel Approach to Understanding Social Behaviors in Pediatric Brain Tumor Survivors: A Pilot Study

BACKGROUND/OBJECTIVES

Pediatric brain tumor survivors (PBTS) are at risk of experiencing challenges in social adjustment. However, the specific social behaviors of PBTS have rarely been directly assessed. This pilot study explores the first novel use of the Autism Diagnostic Observation Schedule, second edition (ADOS-2), to evaluate the social behaviors of PBTS.

METHODS

Twenty-six PBTS (ages 9-17 years; M = 7.8 years from diagnosis; 52% male; 41% received radiation treatment) completed the ADOS-2. The proportion of the sample experiencing impairment was examined descriptively across all items of the ADOS-2, as well as by a summary "overall score" created for this study, and using the ADOS-2 "diagnostic algorithm" scores for autism. Social adjustment, cognitive, medical, and demographic variables were explored as correlates of the ADOS-2 "overall score".

RESULTS

Study recruitment was 34%, impeded by distance from the tertiary-care center. The percentage of PBTS experiencing detectable impairments ranged from 0% to 50% across ADOS-2 items. Cranial radiation treatment, lower IQ, and slower cognitive processing were associated with higher impairment on the ADOS-2 "overall score".

CONCLUSION

The ADOS-2 can be used to assess the discrete social behaviors of PBTS. This study provides a foundation for future investigations using the ADOS-2 to assess social behaviors in this population. Identifying specific social behavior difficulties in PBTS is key to refining much needed targeted social skills interventions for this population.

Electroencephalography in Assessment of Autism Spectrum Disorders: A Review

Electroencephalography (EEG) can further out our understanding of autistic spectrum disorders (ASD) neurophysiology. Epilepsy and ASD comorbidity range between 5 and 46%, but its temporal relationship, causal mechanisms and interplay with intellectual disability are still unknown. Epileptiform discharges with or without seizures go as high as 60%, and associate with epileptic encephalopathies, conceptual term suggesting that epileptic activity can lead to cognitive and behavioral impairment beyond the underlying pathology. Seizures and ASD may be the result of similar mechanisms, such as abnormalities in GABAergic fibers or GABA receptor function. Epilepsy and ASD are caused by a number of genetic disorders and variations that induce such dysregulation. Similarly, initial epilepsy may influence synaptic plasticity and cortical connection, predisposing a growing brain to cognitive delays and behavioral abnormalities. The quantitative EEG techniques could be a useful tool in detecting and possibly measuring dysfunctions in specific brain regions and neuronal regulation in ASD. Power spectra analysis reveals a U-shaped pattern of power abnormalities, with excess power in the low and high frequency bands. These might be the consequence of a complicated network of neurochemical changes affecting the inhibitory GABAergic interneurons and their regulation of excitatory activity in pyramidal cells. EEG coherence studies of functional connectivity found general local over-connectivity and long-range under-connectivity between different brain areas. GABAergic interneuron growth and connections are presumably impaired in the prefrontal and temporal cortices in ASD, which is important for excitatory/inhibitory balance. Recent advances in quantitative EEG data analysis and well-known epilepsy ASD co-morbidity consistently indicate a role of aberrant GABAergic transmission that has consequences on neuronal organization and connectivity especially in the frontal cortex.

Autism and Epilepsy in Patients With Tuberous Sclerosis Complex

Introduction: Individuals with Tuberous Sclerosis Complex (TSC) are at increased risk of developing both epilepsy and autism spectrum disorder (ASD), but the relationship between these conditions is little understood. We reviewed published reports to elucidate the relationship between ASD, epilepsy, and TSC, and to define the genetic and neurological risk factors. Methods: Articles (January 2004-May 2019) were identified via PubMed, EMBASE, and CENTRAL databases. Article inclusion required report on individuals with TSC-associated ASD and epilepsy with prevalence, odds ratio, or rate report on the comorbidity of ASD in epileptic patients due to TSC. Results: A total of 841 abstracts were identified in the original search. Thirty-six articles were included, which identified study populations, ASD measures used, and study confounders as bias factors. This review included 2,666 TSC patients, with a mean age of 15.9 years (range 1.94-30.3 years). The percentage of TSC patients with epilepsy and autism was 33.7%. Patients with TSC and autism showed more frequent seizures and earlier epilepsy onset than TSC patients without autism. ASD and intractable epilepsy were both predicted by a higher number of areas with dysplastic features revealed in brain MR scans. ASD, the onset of seizures in children <2 years of age, and >3 tubers have all been associated with an increased risk of refractory epilepsy in TSC patients. However, the direction of the relationship is not clear because a history of epilepsy, or infantile spasms in patients with TSC is also associated with an increased likelihood of ASD. Overall, 73.2% of patients carried TSC2 genetic variant and, among patients with TSC and autism, the percentage of TSC2 individuals was 85.6%. Conclusions: The complex interrelationship between TSC, autism, and epilepsy, coupled with limited knowledge on the neurobiological basis for the interrelationship, limits overall understanding and opportunities for management. The results of this review highlight the need for early identification and management to optimize favorable outcomes in the most vulnerable individuals with TSC. Regardless of whether studies are considered individually or collectively, interpretation is made difficult due to the differences between the studies, most notably between methods and diagnostic criteria used to assess intellectual ability.

An Updated Review of Tuberous Sclerosis Complex-Associated Autism Spectrum Disorder

Tuberous sclerosis complex (TSC) is a neurocutaneous disorder caused by mutations of either the TSC1 or TSC2 gene. Various neuropsychiatric features, including autism, are prevalent in TSC. Recently, significant progress has been possible with the prospective calculation of the prevalence of autism in TSC, identification of early clinical and neurophysiological biomarkers to predict autism, and investigation of different therapies to prevent autism in this high-risk population. The author provides a narrative review of recent findings related to biomarkers for diagnosis of autism in TSC, as well as recent studies related to the management of TSC-associated autism. Further sophisticated modeling and analysis are required to understand the role of different models-tuber models, seizures and related neurophysiological factors models, genotype models, and brain connectivity models-to unravel the neurobiological basis of autism in TSC. Early neuropsychologic assessments may be beneficial in this high-risk group. Targeted intervention to improve visual skill, cognition, and fine motor skills with later addition of social skill training can be helpful. Multicenter, prospective studies are ongoing to identify if presymptomatic treatment with vigabatrin in patients with TSC can improve outcomes, including autism. Several studies indicated reasonable safety of everolimus in young children, and its potential application in high-risk infants with TSC, before the closure of the temporal window of permanent changes, maybe undertaken shortly.

AIMTOR, a BRET biosensor for live imaging, reveals subcellular mTOR signaling and dysfunctions

Background

mTOR signaling is an essential nutrient and energetic sensing pathway. Here we describe AIMTOR, a sensitive genetically encoded BRET (Bioluminescent Resonance Energy Transfer) biosensor to study mTOR activity in living cells.

Results

As a proof of principle, we show in both cell lines and primary cell cultures that AIMTOR BRET intensities are modified by mTOR activity changes induced by specific inhibitors and activators of mTORC1 including amino acids and insulin. We further engineered several versions of AIMTOR enabling subcellular-specific assessment of mTOR activities. We then used AIMTOR to decipher mTOR signaling in physio-pathological conditions. First, we show that mTORC1 activity increases during muscle cell differentiation and in response to leucine stimulation in different subcellular compartments such as the cytosol and at the surface of the lysosome, the nucleus, and near the mitochondria. Second, in hippocampal neurons, we found that the enhancement of neuronal activity increases mTOR signaling. AIMTOR further reveals mTOR-signaling dysfunctions in neurons from mouse models of autism spectrum disorder.

Conclusions

Altogether, our results demonstrate that AIMTOR is a sensitive and specific tool to investigate mTOR-signaling dynamics in living cells and phenotype mTORopathies.

Modeling Neurodevelopmental Deficits in Tuberous Sclerosis Complex with Stem Cell Derived Neural Precursors and Neurons

Tuberous sclerosis complex (TSC) is a rare genetic disorder that is caused by mutations in TSC1 or TSC2. TSC is a multi-organ disorder characterized by development of non-malignant cellular overgrowths, called hamartomas, in different organs of the body. TSC is also characterized as a neurodevelopmental disorder presenting with epilepsy and autism, and formation of cortical malformations ("tubers"), subependymal giant cell astrocytomas (SEGAs), and subependymal nodules (SENs) in the patient's brain. In this chapter, we are going to give an overview of neural stem cell and neuronal development in TSC. In addition, we will also describe previously developed animal models of TSC that display seizures, autistic-like behaviors, and neuronal cell abnormalities in vivo, and we will compare them to disease phenotypes detected with human stem cell derived neuronal cells in vitro. We will describe the effects of TSC-mutations in different neural cell subtypes, and discuss the mitochondrial function, autophagy, and synaptic development and functional deficits in the neurons. Finally, we will review utilization of these human TSC-patient derived neuronal models for drug screening to develop new treatment options for the neurological phenotypes seen in TSC patients.

Impacting development in infants with tuberous sclerosis complex: Multidisciplinary research collaboration

The Tuberous Sclerosis Complex Autism Center of Excellence Network (TACERN) is a 6-site collaborative conducting longitudinal research on infants with tuberous sclerosis complex (TSC), focused on identifying early biomarkers for autism spectrum disorder (ASD). A multidisciplinary research team that includes the specialties of psychology, neurology, pediatrics, medical genetics, and speech-language pathology, its members work together to conduct studies on neurological status, brain structure and function, neurodevelopmental phenotype, and behavioral challenges in this population. This article provides insights into the roles of the multidisciplinary multisite team and lessons learned from the collaboration, in terms of research as well as training of future researchers and clinicians. In addition, the authors detail the major findings to date, including those related to the identification and measurement of early symptoms of ASD, relationship between seizures and early development, and early biomarkers for epilepsy and developmental delay in infants and young children with TSC. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Tsc1 haploinsufficiency in Nkx2.1 cells upregulates hippocampal interneuron mTORC1 activity, impairs pyramidal cell synaptic inhibition, and alters contextual fear discrimination and spatial working memory in mice

Background

Mutations in TSC1 or TSC2 genes cause tuberous sclerosis complex (TSC), a disorder associated with epilepsy, autism, and intellectual disability. TSC1 and TSC2 are repressors of the mechanistic target of rapamycin complex 1 (mTORC1), a key regulator of protein synthesis. Dysregulation of mTORC1 in TSC mouse models leads to impairments in excitation-inhibition balance, synaptic plasticity, and hippocampus-dependent learning and memory deficits. However, synaptic inhibition arises from multiple types of inhibitory interneurons and how changes in specific interneurons contribute to TSC remains largely unknown. In the present work, we determined the effect of conditional Tsc1 haploinsufficiency in a specific subgroup of inhibitory cells on hippocampal function in mice.

Methods

We investigated the consequences of conditional heterozygous knockout of Tsc1 in MGE-derived inhibitory cells by crossing Nkx2.1^Cre/wt;Tsc1^f/f mice. We examined the changes in mTORC1 activity and synaptic transmission in hippocampal cells, as well as hippocampus-related cognitive tasks.

Results

We detected selective increases in phosphorylation of ribosomal protein S6 in interneurons, indicating cell-specific-upregulated mTORC1 signaling. At the behavioral level, Nkx2.1^Cre/wt;Tsc1^f/wt mice exhibited intact contextual fear memory, but impaired contextual fear discrimination. They displayed intact spatial learning and reference memory but impairment in spatial working memory. Whole-cell recordings in hippocampal slices of Nkx2.1^Cre/wt;Tsc1^f/wt mice showed intact basic membrane properties, as well as miniature excitatory and inhibitory synaptic transmission, in pyramidal and Nkx2.1-expressing inhibitory cells. Using optogenetic activation of Nkx2.1 interneurons in slices of Nkx2.1^Cre/wt;Tsc1^f/wt mice, we found a decrease in synaptic inhibition of pyramidal cells. Chronic, but not acute treatment, with the mTORC1 inhibitor rapamycin reversed the impairment in synaptic inhibition.

Conclusions

Our results indicate that Tsc1 haploinsufficiency in MGE-derived inhibitory cells upregulates mTORC1 activity in these interneurons, reduces their synaptic inhibition of pyramidal cells, and alters contextual fear discrimination and spatial working memory. Thus, selective dysregulation of mTORC1 function in Nkx2.1-expressing inhibitory cells appears sufficient to impair synaptic inhibition and contributes to cognitive deficits in the Tsc1 mouse model of TSC.

Elevated protein synthesis in microglia causes autism-like synaptic and behavioral aberrations

Mutations that inactivate negative translation regulators cause autism spectrum disorders (ASD), which predominantly affect males and exhibit social interaction and communication deficits and repetitive behaviors. However, the cells that cause ASD through elevated protein synthesis resulting from these mutations remain unknown. Here we employ conditional overexpression of translation initiation factor eIF4E to increase protein synthesis in specific brain cells. We show that exaggerated translation in microglia, but not neurons or astrocytes, leads to autism-like behaviors in male mice. Although microglial eIF4E overexpression elevates translation in both sexes, it only increases microglial density and size in males, accompanied by microglial shift from homeostatic to a functional state with enhanced phagocytic capacity but reduced motility and synapse engulfment. Consequently, cortical neurons in the mice have higher synapse density, neuroligins, and excitation-to-inhibition ratio compared to control mice. We propose that functional perturbation of male microglia is an important cause for sex-biased ASD.

Language predictors of autism spectrum disorder in young children with tuberous sclerosis complex

BACKGROUND

Epilepsy has previously been implicated in the development of autism spectrum disorder (ASD) in the setting of tuberous sclerosis complex (TSC). However, the role of language in this relationship is unclear, and the specific relationship between ASD, epilepsy, and language development in this population has not been well-studied.

OBJECTIVES

The objectives the study were to identify the role of early language in subsequent development of ASD, evaluate the impact of epilepsy as a covariate on language development, and evaluate the relationship between epilepsy, language development, and development of ASD.

METHODS

This study included 154 children ages 3-36 months with TSC who were enrolled in the TSC Autism Center of Excellence Research Network (TACERN), a multicenter, prospective observational study to identify biomarkers of ASD. Developmental and autism-specific assessments were administered longitudinally. Appropriate variables from the Mullen Scales of Early Learning (MSEL), Vineland Adaptive Behavior Scales, 2nd Edition (VABS-II), and Preschool Language Scales, 5th Edition (PLS-5) were used to assess patients' language skills. At 36 months, clinical best estimate, which was based on clinical assessment and observation, was used to determine a diagnosis of ASD.

RESULTS

By 12 months, all language variables on the MSEL, PLS-5, and VABS-II significantly predicted an ASD diagnosis at 36 months. Age at seizure onset was associated with language scores in that later seizure onset was associated with improved language scores on the MSEL, VABS-II, and PLS-5. Seizure onset prior to 6 months was associated with a diagnosis of ASD at 36 months. Higher seizure frequency negatively correlated with language scores at 12 months and beyond. Higher seizure frequency was also associated with an ASD diagnosis at 36 months. When looking at the relationship between epilepsy, language, and ASD diagnosis, by 18 months, language scores were more associated with a later ASD diagnosis at 36 months compared with age at seizure onset, which was a better predictor of later ASD diagnosis earlier in development.

CONCLUSION

Analysis of language variables and epilepsy characteristics from 6 to 36 months and ASD diagnosis at 36 months revealed significant relationships between all three variables. While the direction of these relationships needs further research, epilepsy, language, and the development of ASD are integrally related in young children with TSC.

New Horizons for Molecular Genetics Diagnostic and Research in Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a highly heritable, heterogeneous, and complex pervasive neurodevelopmental disorder (PND) characterized by distinctive abnormalities of human cognitive functions, social interaction, and speech development.Nowadays, several genetic changes including chromosome abnormalities, genetic variations, transcriptional epigenetics, and noncoding RNA have been identified in ASD. However, the association between these genetic modifications and ASDs has not been confirmed yet.The aim of this review is to summarize the key findings in ASD from genetic viewpoint that have been identified from the last few decades of genetic and molecular research.

Early patterns of functional brain development associated with autism spectrum disorder in tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is a rare genetic disorder that confers a high risk for autism spectrum disorders (ASD), with behavioral predictors of ASD emerging early in life. Deviations in structural and functional neural connectivity are highly implicated in both TSC and ASD. For the first time, we explore whether electroencephalographic (EEG) measures of neural network function precede or predict the emergence of ASD in TSC. We determine whether altered brain function (a) is present in infancy in TSC, (b) differentiates infants with TSC based on ASD diagnostic status, and (c) is associated with later cognitive function. We studied 35 infants with TSC (N = 35), and a group of typically developing infants (N = 20) at 12 and 24 months of age. Infants with TSC were later subdivided into ASD and non-ASD groups based on clinical evaluation. We measured features of spontaneous alpha oscillations (6-12 Hz) that are closely associated with neural network development: alpha power, alpha phase coherence (APC), and peak alpha frequency (PAF). Infants with TSC demonstrated reduced interhemispheric APC compared to controls at 12 months of age, and these differences were found to be most pronounced at 24 months in the infants who later developed ASD. Across all infants, PAF at 24 months was associated with verbal and nonverbal cognition at 36 months. Associations between early network function and later neurodevelopmental and cognitive outcomes highlight the potential utility of early scalable EEG markers to identify infants with TSC requiring additional targeted intervention initiated very early in life. Autism Res 2019, 12: 1758-1773. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Approximately half of infants with tuberous sclerosis complex (TSC) develop autism. Here, using EEG, we find that there is a reduction in communication between brain regions during infancy in TSC, and that the infants who show the largest reductions are those who later develop autism. Being able to identify infants who show early signs of disrupted brain development may improve the timing of early prediction and interventions in TSC, and also help us to understand how early brain changes lead to autism.

Single and staged laser interstitial thermal therapy ablation for cortical tubers causing refractory epilepsy in pediatric patients

OBJECTIVE Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) is a novel, minimally invasive treatment for the surgical treatment of epilepsy. In this paper, the authors report on clinical outcomes for a series of pediatric patients with tuberous sclerosis complex (TSC) and medication-refractory epileptogenic cortical tubers. METHODS A retrospective chart review was performed at SUNY Upstate Golisano Children's Hospital in Syracuse, New York. The authors included all cases involving pediatric patients (< 18 years) who underwent MRgLITT for ablation of epileptogenic cortical tubers between February 2013 and November 2015. RESULTS Seven patients with cortical tubers were treated (4 female and 3 male). The patients' average age was 6.6 years (range 2-17 years). Two patients had a single procedure, and 5 patients had staged procedures. The mean time between procedures in the staged cases was 6 months. All of the patients had a meaningful reduction in seizure frequency as reported by Engel and ILAE seizure outcome classifications, and most (71.4%) of the patients experienced a reduction in AED burden. Three of the 4 patients who presented with neuropsychiatric symptoms had some improvement in these domains after laser ablation. No perioperative complications were noted. The mean duration of follow-up was 19.3 months (range 4-49 months). CONCLUSIONS Laser ablation represents a minimally invasive alternative to resective epilepsy surgery and is an effective treatment for refractory epilepsy due to cortical tubers.

Reproducibility of Structural and Diffusion Tensor Imaging in the TACERN Multi-Center Study

BACKGROUND

Multi-site MRI studies are often necessary for recruiting sufficiently sized samples when studying rare conditions. However, they require pooling data from multiple scanners into a single data set, and therefore it is critical to evaluate the variability of quantitative MRI measures within and across scanners used in multi-site studies. The aim of this study was to evaluate the reproducibility of structural and diffusion weighted (DW) MRI measurements acquired on seven scanners at five medical centers as part of the Tuberous Sclerosis Complex Autism Center of Excellence Research Network (TACERN) multisite study.

METHODS

The American College of Radiology (ACR) phantom was imaged monthly to measure reproducibility of signal intensity and uniformity within and across seven 3T scanners from General Electric, Philips, and Siemens vendors. One healthy adult male volunteer was imaged repeatedly on all seven scanners under the TACERN structural and DW protocol (5 b = 0 s/mm2 and 30 b = 1000 s/mm2) over a period of 5 years (age 22-27 years). Reproducibility of inter- and intra-scanner brain segmentation volumes and diffusion tensor imaging metrics fractional anisotropy (FA) and mean diffusivity (MD) within white matter regions was quantified with coefficient of variation.

RESULTS

The American College of Radiology Phantom signal intensity and uniformity were similar across scanners and changed little over time, with a mean intra-scanner coefficient of variation of 3.6 and 1.8%, respectively. The mean inter- and intra-scanner coefficients of variation of brain structure volumes derived from T1-weighted (T1w) images of the human phantom were 3.3 and 1.1%, respectively. The mean inter- and intra-scanner coefficients of variation of FA in white matter regions were 4.5 and 2.5%, while the mean inter- and intra-scanner coefficients of variation of MD in white matter regions were 5.4 and 1.5%.

CONCLUSION

Our results suggest that volumetric and diffusion tensor imaging (DTI) measurements are highly reproducible between and within scanners and provide typical variation amplitudes that can be used as references to interpret future findings in the TACERN network.

Resting-State fMRI Networks in Children with Tuberous Sclerosis Complex

BACKGROUND AND PURPOSE

There are no published studies examining resting state networks (RSNs) and their relationship with neurodevelopmental metrics in tuberous sclerosis complex (TSC). We aimed to identify major resting-state functional magnetic resonance imaging (rs-fMRI) networks in infants with TSC and correlate network analyses with neurodevelopmental assessments, autism diagnosis, and seizure history.

METHODS

Rs-fMRI data from 34 infants with TSC, sedated with propofol during the scan, were analyzed to identify auditory, motor, and visual RSNs. We examined the correlations between auditory, motor, and visual RSNs at approximately 11.5 months, neurodevelopmental outcome at approximately 18.5 months, and diagnosis of autism spectrum disorders at approximately 36 months of age.

RESULTS

RSNs were obtained in 76.5% (26/34) of infants. We observed significant negative correlations between auditory RSN and auditory comprehension test scores (p = .038; r = -.435), as well as significant positive correlations between motor RSN and gross motor skills test scores (p = .023; r = .564). Significant positive correlations between motor RSNs and gross motor skills (p = .012; r = .754) were observed in TSC infants without autism, but not in TSC infants with autism, which could suggest altered motor processing. There were no significant differences in RSNs according to seizure history.

CONCLUSIONS

Negative correlation between auditory RSN, as well as positive correlation between motor RSN and developmental outcome measures might reflect different brain mechanisms and, when identified, may be helpful in predicting later function. A larger study of TSC patients with a healthy control group is needed before auditory and motor RSNs could be considered as neurodevelopmental outcome biomarkers.

Early Clinical Predictors of Autism Spectrum Disorder in Infants with Tuberous Sclerosis Complex: Results from the EPISTOP Study

Autism spectrum disorder (ASD) is highly prevalent in subjects with Tuberous Sclerosis Complex (TSC), but we are not still able to reliably predict which infants will develop ASD. This study aimed to identify the early clinical markers of ASD and/or developmental delay (DD) in infants with an early diagnosis of TSC. We prospectively evaluated 82 infants with TSC (6-24 months of age), using a detailed neuropsychological assessment (Bayley Scales of Infant Development-BSID, and Autism Diagnostic Observation Schedule-ADOS), in the context of the EPISTOP (Long-term, prospective study evaluating clinical and molecular biomarkers of EPIleptogenesiS in a genetic model of epilepsy-Tuberous SclerOsis ComPlex) project (NCT02098759). Normal cognitive developmental quotient at 12 months excluded subsequent ASD (negative predictive value 100%). The total score of ADOS at 12 months clearly differentiated children with a future diagnosis of ASD from children without (p = 0.012). Atypical socio-communication behaviors (p < 0.001) were more frequently observed than stereotyped/repetitive behaviors in children with ASD at 24 months. The combined use of BSID and ADOS can reliably identify infants with TSC with a higher risk for ASD at age 6-12 months, allowing for clinicians to target the earliest symptoms of abnormal neurodevelopment with tailored intervention strategies.

Is there an "antisocial" cerebellum? Evidence from disorders other than autism characterized by abnormal social behaviours

The cerebellum is a hindbrain structure which involvement in functions not related to motor control and planning is being increasingly recognized in the last decades. Studies on Autism Spectrum Disorders (ASD) have reported cerebellar involvement on these conditions characterized by social deficits and repetitive motor behavior patterns. Although such an involvement hints at a possible cerebellar participation in the social domain, the fact that ASD patients present both social and motor deficits impedes drawing any firm conclusion regarding cerebellar involvement in pathological social behaviours, probably influenced by the classical view of the cerebellum as a purely "motor" brain structure. Here, we suggest the cerebellum can be a key node for the production and control of normal and particularly aberrant social behaviours, as indicated by its involvement in other neuropsychiatric disorders which main symptom is deregulated social behaviour. Therefore, in this work, we briefly review cerebellar involvement in social behavior in rodent models, followed by discussing the findings linking the cerebellum to those other psychiatric conditions characterized by defective social behaviours. Finally, possible commonalities between the studies and putative underlying impaired functions will be discussed and experimental approaches both in patients and experimental animals will also be proposed, aimed at stimulating research on the role of the cerebellum in social behaviours and disorders characterized by social impairments, which, if successful, will definitely help reinforcing the proposed cerebellar involvement in the social domain.