CNTN6 copy number variations in 14 patients: a possible candidate gene for neurodevelopmental and neuropsychiatric disorders

Background

Neurodevelopmental disorders are impairments of brain function that affect emotion, learning, and memory. Copy number variations of contactin genes (CNTNs), including CNTN3, CNTN4, CNTN5, and CNTN6, have been suggested to be associated with these disorders. However, phenotypes have been reported in only a handful of patients with copy number variations involving CNTNs.

Methods

From January 2009 to January 2013, 3724 patients ascertained through the University of Pittsburgh Medical Center were referred to our laboratory for clinical array comparative genomic hybridization testing. We screened this cohort of patients to identify individuals with the 3p26.3 copy number variations involving the CNTN6 gene, and then retrospectively reviewed the clinical information and family history of these patients to determine the association between the 3p26.3 copy number variations and neurodevelopmental disorders.

Results

Fourteen of the 3724 patients had 3p26.3 copy number variations involving the CNTN6 gene. Thirteen of the 14 patients with these CNTN6 copy number variations presented with various neurodevelopmental disorders including developmental delay, autistic spectrum disorders, seizures and attention deficit hyperactivity disorder. Family history was available for 13 of the 14 patients. Twelve of the thirteen families have multiple members with neurodevelopmental and neuropsychiatric disorders including attention deficit hyperactivity disorder, seizures, autism spectrum disorder, intellectual disability, schizophrenia, depression, anxiety, learning disability, and bipolar disorder.

Conclusions

Our findings suggest that deletion or duplication of the CNTN6 gene is associated with a wide spectrum of neurodevelopmental behavioral disorders.     

Mobile EEG in research on neurodevelopmental disorders: Opportunities and challenges

Mobile electroencephalography (mobile EEG) represents a next-generation neuroscientific technology – to study real-time brain activity – that is relatively inexpensive, non-invasive and portable. Mobile EEG leverages state-of-the-art hardware alongside established advantages of traditional EEG and recent advances in signal processing. In this review, we propose that mobile EEG could open unprecedented possibilities for studying neurodevelopmental disorders. We first present a brief overview of recent developments in mobile EEG technologies, emphasising the proliferation of studies in several neuroscientific domains. As these developments have yet to be exploited by neurodevelopmentalists, we then identify three research opportunities: 1) increase in the ease and flexibility of brain data acquisition in neurodevelopmental populations; 2) integration into powerful developmentally-informative research designs; 3) development of innovative non-stationary EEG-based paradigms. Critically, we address key challenges that should be considered to fully realise the potential of mobile EEG for neurodevelopmental research and for understanding developmental psychopathology more broadly, and suggest future research directions.     

Environmental toxicology: Sensitive periods of development and neurodevelopmental disorders

Development of the mammalian central nervous system is a complex process whose disruption may have severe and long-lasting consequences upon brain structure and function, potentially resulting in a neurodevelopmental disorder (NDD). Many NDDs are known to be genetic in origin, with symptom onset and their underlying mechanisms now known to be regulated during time-dependent windows or ‘critical periods’ during normal brain development. However, it is increasingly evident that similar disturbances to the developing nervous system may be caused by exposure to non-genetic, environmental factors. Strikingly, at least 200 industrially applied or produced chemicals have been associated with neurotoxicity in humans and exposure to these modifying compounds, through consumer products or environmental pollution, therefore poses serious threats to public health. Through a combination of human epidemiological and animal experimental studies, we identified developmental periods for increased vulnerability to environmentally-modifying compounds and determined whether and how exposure during specific sensitive time-windows could increase the risk for the NDDs of autism, ADHD or schizophrenia in the developing organism. We report that many environmental toxicants have distinct sensitive time-windows during which exposure may disrupt critical developmental events, thereby increasing the risk of developing NDDs. The majority of these time-windows occur prenatally rather than postnatally. We propose four underlying mechanisms that mediate pathogenesis, namely oxidative stress, immune system dysregulation, altered neurotransmission and thyroid hormone disruption. Given the complexity of underlying mechanisms and their prenatal inception, treatment options are currently limited. Thus, we conclude that preventing early exposure to environmental toxicants, by increasing public awareness and improving government and industry guidelines, may ultimately lead to a significant reduction in the incidence of NDDs.     

Adult reversal of cognitive phenotypes in neurodevelopmental disorders

Recent findings in mice suggest that it is possible to reverse certain neurodevelopmental disorders in adults. Changes in development, previously thought to be irreparable in adults, were believed to underlie the neurological and psychiatric phenotypes of a range of common mental health problems with a clear developmental component. As a consequence, most researchers have focused their efforts on understanding the molecular and cellular processes that alter development with the hope that early intervention could prevent the emergent pathology. Unexpectedly, several different animal model studies published recently, including animal models of autism, suggest that it may be possible to reverse neurodevelopmental disorders in adults: Addressing the underlying molecular and cellular deficits in adults could in several cases dramatically improve the neurocognitive phenotypes in these animal models. The findings reviewed here provide hope to millions of individuals afflicted with a wide range of neurodevelopmental disorders, including autism, since they suggest that it may be possible to treat or even cure them in adults.     

Linkage analysis and exome sequencing identify a novel mutation in KCTD7 in patients with progressive myoclonus epilepsy with ataxia

Epilepsy affects approximately 1% of the world's population. Genetic factors and acquired etiologies, as well as a range of environmental triggers, together contribute to epileptogenesis. We have identified a family with three daughters affected with progressive myoclonus epilepsy with ataxia. Clinical details of the onset and progression of the neurologic presentation, epileptic seizures, and the natural history of progression over a 10‐year period are described. Using autozygosity genetic mapping, we identified a high likelihood homozygous region on chromosome 7p12.1‐7q11.22. We subsequently applied whole‐exome sequencing and employed a rare variant prioritization analysis within the homozygous region. We identified p.Tyr276Cys in the potassium channel tetramerization domain–containing seven gene, KCTD7, which is expressed predominantly in the brain. Mutations in this gene have been implicated previously in epileptic phenotypes due to disturbances in potassium channel conductance. Pathogenicity of the mutation was supported by bioinformatic predictive analyses and variant cosegregation within the family. Further biologic validation is necessary to fully characterize the pathogenic mechanisms that explain the phenotypic causes of epilepsy with ataxia in these patients.     

Connecting brain and body: Transdiagnostic relevance of connective tissue variants to neuropsychiatric symptom expression

The mind is embodied; thoughts and feelings interact with states of physiological arousal and physical integrity of the body. In this context, there is mounting evidence for an association between psychiatric presentations and the expression variant connective tissue, commonly recognised as joint hypermobility. Joint hypermobility is common, frequently under-recognised, significantly impacts quality of life, and can exist in isolation or as the hallmark of hypermobility spectrum disorders (encompassing joint hypermobility syndrome and hypermobile Ehlers-Danlos syndrome). In this narrative review, we appraise the current evidence linking psychiatric disorders across the lifespan, beginning with the relatively well-established connection with anxiety, to hypermobility. We next consider emerging associations with affective illnesses, eating disorders, alongside less well researched links with personality disorders, substance misuse and psychosis. We then review related findings relevant to neurodevelopmental disorders and stress-sensitive medical conditions. With growing understanding of mind-body interactions, we discuss potential aetiopathogenetic contributions of dysautonomia, aberrant interoceptive processing, immune dysregulation and proprioceptive impairments in the context of psychosocial stressors and genetic predisposition. We examine clinical implications of these evolving findings, calling for increased awareness amongst healthcare professionals of the transdiagnostic nature of hypermobility and related disorders. A role for early screening and detection of hypermobility in those presenting with mental health and somatic symptoms is further highlighted, with a view to facilitate preventative approaches alongside longer-term holistic management strategies. Finally, suggestions are offered for directions of future scientific exploration which may be key to further delineating fundamental mind-body-brain interactions.     

Fetal alcohol syndrome and the risk of neurodevelopmental disorders: A longitudinal cohort study

BackgroundThis hypothesis-testing study evaluated the relationship between fetal alcohol syndrome (FAS) and neurodevelopmental disorder (ND) diagnoses within the Independent Healthcare Research Database (IHRD).MethodsDe-identified eligibility and claim healthcare records prospectively generated from the 1990–2012 Florida Medicaid system were analyzed using SAS software. There were 89,766 children continuously eligible with ≥10 outpatient office visits during the 120 month period following birth in the cohort examined. A total of 321 children were diagnosed with FAS. Autism spectrum disorder (ASD) (n = 922), tics (n = 551), attention deficit disorder/attention deficit-hyperactivity disorder (ADD/ADHD) (n = 20,260), mental retardation (MR) (n = 915), and specific delays in development (SDD) (n = 24,630) incidence rates were examined using frequency risk ratio (RR) and logistic regression models.ResultsThe incidence rate of tics (RR = 5.68), ADD/ADHD (RR = 2.30), MR (RR = 7.83), SDD (RR = 2.88), and ASD (RR = 6.74) were significantly increased among FAS diagnosed children as compared to undiagnosed children. Adjusted (for gender, race, residency, and date of birth) odds ratios (ORs) were significantly increased for tics (OR = 4.87), ADD/ADHD (OR = 3.40), MR (OR = 7.91), SDD (OR = 9.56), and ASD (OR = 6.87) when comparing the FAS diagnosed children to undiagnosed children.ConclusionTens of thousands of American children with lifetime costs in the billions of US dollars were estimated to be impacted by FAS-associated NDs. These impacts are particularly tragic because FAS is dependent upon lifestyle.     

Celiac disease and risk of neuropsychiatric disorders: A nationwide cohort study

Introduction

Previous studies have indicated that patients with celiac disease (CD) may have an increased risk of developing neuropsychiatric disorders. However, large-scale epidemiologic studies on the topic are still scarce. We aimed to examine the association between CD and development of neuropsychiatric disorders during an 18-year follow-up period.

Methods

We conducted a prospective cohort study. All Danish patients with an incident diagnosis of CD (ICD-10 K90.0) from 2000 to 2018 were identified in nationwide registries and compared with birthdate- and sex-matched controls (variable 1:10 ratio) for the development of a neuropsychiatric disease. Individual neuropsychiatric diseases were also examined. The absolute risk was calculated by the cumulative incidence, and the relative risk was estimated in Cox regression models.

Results

We identified a cohort of 6329 patients with CD diagnosed from 2000 to 2018 and 63,287 matches at risk for developing incident neuropsychiatric disorders. The cumulative incidence of development of any neuropsychiatric disorder was 3.9%, 14.9%, 24.8%, 35.9% after 1, 5, 10, and 15 years of follow-up, respectively, in patients with CD compared with 1.8%, 9.3%, 18.3%, and 27.0% in controls. Gray's test for equality p < 0.001. The relative risk was HR = 1.58 (95% confidence interval: 1.49–1.68) in CD patients compared with matches. For the individual outcomes, CD was associated with an increased relative risk of developing anxiety, depression, eating disorders, epilepsy, migraine, and stress. We also found indications of an increased relative risk of ADHD, alcoholism, bipolar disorders, and drug abuse, although the associations were less clear. No associations were found between CD and dementia, Parkinson's disease, and schizophrenia.

Conclusions

In this nationwide study including more than 6000 patients with CD, we found an increased risk of development of a neuropsychiatric disorder compared with age- and sex-matched controls. The causes and the clinical relevance of these associations remain to be elucidated.     

Sensitive and critical periods during neurotypical and aberrant neurodevelopment: A framework for neurodevelopmental disorders

During sensitive and critical periods, the brain undergoes significant plasticity from the level of individual synapses and neuronal networks up to the level of behaviour. Both sensitive and critical periods during neurotypical development of the young animal provide a framework to the early temporally-regulated modifications that occur in the nervous system.In neurodevelopmental disorders (NDD), notably autistic syndromes and intellectual disability, children exhibit developmental delays in motor, social and sensory processes and often miss key developmental milestones. In corresponding genetic NDD mouse models, recent data reveal temporally-regulated and in some cases, transient impairments in many neuronal and behavioural phenotypes during development. However, the mechanisms underlying these impairments in NDDs and their potential links with neurobiological mechanisms governing neurotypical development are not fully investigated. This article highlights the potential for the use of known critical and sensitive periods during vertebrate development to investigate and advance our understanding of the neural bases underlying impairments in these developmental disorders of the nervous system.     

Conceptualising compensation in neurodevelopmental disorders: Reflections from autism spectrum disorder

Within research into neurodevelopmental disorders, little is known about the mechanisms underpinning changes in symptom severity across development. When the behavioural presentation of a condition improves/symptoms lessen, this may be because core underlying atypicalities in cognition/neural function have ameliorated. An alternative possibility is ‘compensation’; that the behavioural presentation appears improved, despite persisting deficits at cognitive and/or neurobiological levels. There is, however, currently no agreed technical definition of compensation or its behavioural, cognitive and neural characteristics. Furthermore, its workings in neurodevelopmental disorders have not been studied directly. Here, we review current evidence for compensation in neurodevelopmental disorders, using Autism Spectrum Disorder as an example, in order to move towards a better conceptualisation of the construct. We propose a transdiagnostic framework, where compensation represents the processes responsible for an observed mismatch between behaviour and underlying cognition in a neurodevelopmental disorder, at any point in development. Further, we explore potential cognitive and neural mechanisms driving compensation and discuss the broader relevance of the concept within research and clinical settings.     

An evaluation of speech production in two boys with neurodevelopmental disorders who received communication intervention with a speech-generating device

BackgroundChildren with neurodevelopmental disorders often present with little or no speech. Augmentative and alternative communication (AAC) aims to promote functional communication using non-speech modes, but it might also influence natural speech production.MethodTo investigate this possibility, we provided AAC intervention to two boys with neurodevelopmental disorders and severe communication impairment. Intervention focused on teaching the boys to use a tablet computer-based speech-generating device (SGD) to request preferred stimuli. During SGD intervention, both boys began to utter relevant single words. In an effort to induce more speech, and investigate the relation between SGD availability and natural speech production, the SGD was removed during some requesting opportunities.ResultsWith intervention, both participants learned to use the SGD to request preferred stimuli. After learning to use the SGD, both participants began to respond more frequently with natural speech when the SGD was removed.ConclusionThe results suggest that a rehabilitation program involving initial SGD intervention, followed by subsequent withdrawal of the SGD, might increase the frequency of natural speech production in some children with neurodevelopmental disorders. This effect could be an example of response generalization.     

Offspring neuroimmune consequences of maternal malnutrition: Potential mechanism for behavioral impairments that underlie metabolic and neurodevelopmental disorders

Maternal malnutrition significantly increases offspring risk for both metabolic and neurodevelopmental disorders. Animal models of maternal malnutrition have identified behavioral changes in the adult offspring related to executive function and reward processing. Together, these changes in executive and reward-based behaviors likely contribute to the etiology of both metabolic and neurodevelopmental disorders associated with maternal malnutrition. Concomitant with the behavioral effects, maternal malnutrition alters offspring expression of reward-related molecules and inflammatory signals in brain pathways that control executive function and reward. Neuroimmune pathways and microglial interactions in these specific brain circuits, either in early development or later in adulthood, could directly contribute to the maternal malnutrition-induced behavioral phenotypes. Understanding these mechanisms will help advance treatment strategies for metabolic and neurodevelopmental disorders, especially noninvasive dietary supplementation interventions.     

A compensatory role for declarative memory in neurodevelopmental disorders

Most research on neurodevelopmental disorders has focused on their abnormalities. However, what remains intact may also be important. Increasing evidence suggests that declarative memory, a critical learning and memory system in the brain, remains largely functional in a number of neurodevelopmental disorders. Because declarative memory remains functional in these disorders, and because it can learn and retain numerous types of information, functions, and tasks, this system should be able to play compensatory roles for multiple types of impairments across the disorders. Here, we examine this hypothesis for specific language impairment, dyslexia, autism spectrum disorder, Tourette syndrome, and obsessive–compulsive disorder. We lay out specific predictions for the hypothesis and review existing behavioral, electrophysiological, and neuroimaging evidence. Overall, the evidence suggests that declarative memory indeed plays compensatory roles for a range of impairments across all five disorders. Finally, we discuss diagnostic, therapeutic and other implications.     

Ultrasonic vocalizations in mice: relevance for ethologic and neurodevelopmental disorders studies

Mice use ultrasonic vocalizations(USVs) to communicate each other and to convey their emotional state. USVs have been greatly characterized in specific life phases and contexts, such as mother isolation-induced USVs for pups or female-induced USVs for male mice during courtship. USVs can be acquired by means of specific tools and later analyzed on the base of both quantitative and qualitative parameters. Indeed, different ultrasonic call categories exist and have already been defined. The understanding of different calls meaning is still missing, and it will represent an essential step forward in the field of USVs. They have long been studied in the ethological context, but recently they emerged as a precious instrument to study pathologies characterized by deficits in communication, in particular neurodevelopmental disorders(NDDs), such as autism spectrum disorders. This review covers the topics of USVs characteristics in mice, contexts for USVs emission and factors that modulate their expression. A particular focus will be devoted to mouse USVs in the context of NDDs. Indeed, several NDDs murine models exist and an intense study of USVs is currently in progress, with the aim of both performing an early diagnosis and to find a pharmacological/behavioral intervention to improve patients' quality of life.     

Sleep disorders in children with cerebral palsy: neurodevelopmental and behavioral correlates

ObjectivesWe aimed to estimate the frequency of sleep disorders in children with cerebral palsy (CP) using the Sleep Disturbance Scale for Children (SDSC) and to evaluate the relations between sleep disorders and motor, cognitive, and behavioral problems.MethodsOne hundred and sixty-five children with CP ages 6–16 years (mean age, 11 years) were assessed using the SDSC, the Gross Motor Function Classification System (GMFCS), the Wechsler Intelligence Scale for Children and the Child Behavior Check List (CBCL) to assess sleep, motor, cognitive, and behavioral problems, respectively.ResultsAn abnormal total sleep score was found in 19% of children with CP; more than 40% of children had an abnormal score on at least one SDSC factor. The SDSC total score was significantly associated (P < .01) with mental retardation, epilepsy, CBCL scores, and level 5 on the GMFCS.ConclusionsOur results confirm that sleep disorders are common in children with cerebral palsy. The relationship between motor and cognitive behavior and epilepsy should be further explored to better understand how these factors influence one another to identify effective treatments and to improve the well-being of the child.     

Family quality of life among families with a child who has a severe neurodevelopmental disability: Impact of family and child socio-demographic factors

We aimed to examine family quality of life (FQOL) of Northern Israeli families having a child with a severe neurodevelopmental disability and its relation to socio-demographics. The cohort included caregivers of 70 children ages (mean ± standard deviation) 5.36 ± 3.53 years. Families were two-parent (85.7%), lived in the periphery (67.1%) and included Jews (60%), Muslims (18.6%), Druze (14.3%) and Christians (7.1%). Religiosity included: secular (38.6%), traditional (31.4%), religious (30%). Children's diagnosis included autistic spectrum disorder (41.4%), intellectual disability (21.4%), cerebral palsy (17.1%), genetic syndromes (17.1%) and sensorineural hearing loss (2.9%). Degree of support (1-minimal,5-greatest) required by the child was 3.67 ± 1.28 for physical and 3.49 ± 1.36 for communication. Primary caregivers completed the FQOL Survey. Domain scores were highest for family relations and lowest for financial well-being. Dimension scores were highest for importance and lowest for opportunities. Overall FQOL approximated average. Jewish families and residents of a major urban area reported higher and more religious families reported lower overall FQOL. Regression analysis found ethnicity contributing to overall FQOL and domain scores with residence contributing to support from services. Ethnicity and child dependence contributed to dimension scores. Northern Israeli families having a child with a severe neurodevelopmental disability report average FQOL scores. However, family and child dependence characteristics affect FQOL scores. Professionals working with these families should consider FQOL information when making recommendations.