Angelman syndrome: a review of the clinical and genetic aspects

Lipids shape brain function through ion channel and receptor modulations: physiological mechanisms and clinical perspectives

Lipids represent the most abundant molecular type in the brain, with a fat content of ∼60% of the dry brain weight in humans. Despite this fact, little attention has been paid to circumscribe the dynamic role of lipids in brain function and disease. Membrane lipids such as cholesterol, phosphoinositide, sphingolipids, arachidonic acid, and endocannabinoids finely regulate both synaptic receptors and ion channels that ensure critical neural functions. After a brief introduction on brain lipids and their respective properties, we review here their role in regulating synaptic function and ion channel activity, action potential propagation, neuronal development, and functional plasticity and their contribution in the development of neurological and neuropsychiatric diseases. We also provide possible directions for future research on lipid function in brain plasticity and diseases.

Genotype-phenotype correlation over time in Angelman syndrome: Researching 134 patients

Angelman syndrome (AS) is a severe neurodevelopmental disorder caused by the loss of function of maternal UBE3A. The major cause of AS is a maternal deletion in 15q11.2-q13, and the minor causes are a UBE3A mutation, uniparental disomy (UPD), and imprinting defect (ID). Previous reports suggest that all patients with AS exhibit developmental delay, movement or balance disorders, behavioral characteristics, and speech impairment. In contrast, a substantial number of AS patients with a UBE3A mutation, UPD, or ID were reported not to show these consistent features and to show age-dependent changes in their features. In this study, we investigated 134 patients with AS, including 57 patients with a UBE3A mutation and 48 patients with UPD or ID. Although developmental delay was present in all patients, 20% of patients with AS caused by UPD or ID did not exhibit movement or balance disorders. Differences were also seen in hypopigmentation and seizures, depending on the causes. Moreover, patients with a UBE3A mutation, UPD, or ID tended to show fewer of the specific phenotypes depending on their age. In particular, in patients with UPD or ID, easily provoked laughter and hyperactivity tended to become more pronounced as they aged. Therefore, the clinical features of AS based on cause and age should be understood, and genetic testing should not be limited to patients with the typical clinical features of AS.

Do metabolic deficits contribute to sleep disruption in monogenic intellectual disability syndromes?

Intellectual disability is defined as limitations in cognitive and adaptive behavior that often arise during development. Disordered sleep is common in intellectual disability and, given the importance of sleep for cognitive function, it may contribute to other behavioral phenotypes. Animal models of intellectual disability, in particular of monogenic intellectual disability syndromes (MIDS), recapitulate many disease phenotypes and have been invaluable for linking some of these phenotypes to specific molecular pathways. An emerging feature of MIDS, in both animal models and humans, is the prevalence of metabolic abnormalities, which could be relevant for behavior. Focusing on specific MIDS that have been molecularly characterized, we review sleep, circadian, and metabolic phenotypes in animal models and humans and propose that altered metabolic state contributes to the abnormal sleep/circadian phenotypes in MIDS.

Ube3a unsilencer for the potential treatment of Angelman syndrome

Deletion of the maternal UBE3A allele causes Angelman syndrome (AS); because paternal UBE3A is epigenetically silenced by a long non-coding antisense (UBE3A-ATS) in neurons, this nearly eliminates UBE3A protein in the brain. Reactivating paternal UBE3A holds promise for treating AS. We previously showed topoisomerase inhibitors can reactivate paternal UBE3A, but their therapeutic challenges prompted our search for small molecule unsilencers with a different mechanism of action. Here, we found that (S)-PHA533533 acts through a novel mechanism to significantly increase paternal Ube3a mRNA and UBE3A protein levels while downregulating Ube3a-ATS in primary neurons derived from AS model mice. Furthermore, peripheral delivery of (S)-PHA533533 in AS model mice induces widespread neuronal UBE3A expression. Finally, we show that (S)-PHA533533 unsilences paternal UBE3A in AS patient-derived neurons, highlighting its translational potential. Our findings provide a lead for developing a small molecule treatment for AS that could be safe, non-invasively delivered, and capable of brain-wide unsilencing of paternal UBE3A.

Developmental milestones and daily living skills in individuals with Angelman syndrome

BACKGROUND

Angelman syndrome (AS) is a neurodevelopmental disorder associated with severe global developmental delay. However, the ages at which different developmental skills are achieved in these individuals remain unclear. We seek to determine the probability and the age of acquisition of specific developmental milestones and daily living skills in individuals with AS across the different molecular subtypes, viz. class I deletion, class II deletion, uniparental disomy, imprinting defect, and UBE3A variants.

METHODS

Caregivers participating in a longitudinal multicenter Angelman Syndrome Natural History Study completed a questionnaire regarding the age at which their children achieved specific developmental milestones and daily living skills. The Cox Proportional Hazard model was applied to analyze differences in the probability of achievement of skills at various ages among five molecular subtypes of AS.

RESULTS

Almost all individuals, regardless of molecular subtype, were able to walk with support by five years of age. By age 15, those with a deletion had at least a 50% probability of acquiring 17 out of 30 skills compared to 25 out of 30 skills among those without a deletion. Overall, fine and gross motor skills such as holding and reaching for small objects, sitting, and walking with support were achieved within a fairly narrow range of ages, while toileting, feeding, and hygiene skills tend to have greater variability in the ages at which these skills were achieved. Those without a deletion had a higher probability (25-92%) of achieving daily living skills such as independently toileting and dressing compared to those with a deletion (0-13%). Across all molecular subtypes, there was a low probability of achieving independence in bathing and brushing teeth.

CONCLUSION

Individuals with AS without a deletion are more likely to achieve developmental milestones and daily living skills at an earlier age than those with a deletion. Many individuals with AS are unable to achieve daily living skills necessary for independent self-care.

The Type, Severity, and Impact of Sleep Problems in Children With Angelman Syndrome and Parental Help-seeking Patterns

Angelman syndrome (AS) is a rare genetic developmental disability that presents with high rates of co-occurring sleep difficulties. Most existing research has focused on the pathophysiology of sleep problems in people with AS, and suggests that sleep problems are the result of genetic and neurobiological factors. However, little is known about the role of the social environment and learning in sleep problems in children with AS. This descriptive study used survey data from 139 parents of children with AS to investigate: 1) the type, topography and severity of children's sleep problems; 2) the collateral child, parent and family impacts of the sleep problems; 3) treatment selection practices and the perceived effectiveness of these treatments; and 4) sources of support and treatment advice received. Parents reported that the majority of children experienced sleep problems, resulting in numerous deleterious effects on child and family functioning. They also reported high levels of concern about these sleep problems, but low levels of perceived support. Study findings highlight the need to establish a disability-specific profile of the type and impact of sleep problems experienced by children with AS, and have further implications for the delivery of clinical services and support provided to parents of children with AS.

Factors associated with sleep disturbances in children and adolescents with Angelman Syndrome

BACKGROUND

Angelman Syndrome (AS) is a rare genetic disorder characterised by hyperactivity, overexcitability, developmental delays, and lack of speech.

METHODS

This study used secondary data analysis to investigate sleep disturbances in children and adolescents (n = 212) who are enrolled in the Global Angelman Syndrome Registry. Participants were divided into two groups based on the presence or absence of sleep disturbance. The cut-off score of 40 on the Sleep Disturbance Scale for Children was used to indicate the presence or absence of sleep disturbances. Sleep disturbances and their association with co-occurring conditions were examined regarding challenging behaviour, language and communication, infancy history, gastrointestinal symptoms, and epilepsy. Multiple regression was then conducted to investigate possible predictors for sleep disturbances.

RESULTS

Children and adolescents with AS, with and without sleep disturbances, differed considerably regarding anxiety. Sleep disturbances were significantly associated with an ability to use spoken words and computerised communication devices, and anxiety was a predictor of sleep disturbances.

CONCLUSION

Future research is necessary to replicate this novel research, and to advance the clinical treatment of sleep disturbances in children and adolescents with AS.

Activation of the imprinted Prader-Willi Syndrome locus by CRISPR-based epigenome editing

Epigenome editing with DNA-targeting technologies such as CRISPR-dCas9 can be used to dissect gene regulatory mechanisms and potentially treat associated disorders. For example, Prader-Willi Syndrome (PWS) is caused by loss of paternally expressed imprinted genes on chromosome 15q11.2-q13.3, although the maternal allele is intact but epigenetically silenced. Using CRISPR repression and activation screens in human induced pluripotent stem cells (iPSCs), we identified genomic elements that control expression of the PWS gene SNRPN from the paternal and maternal chromosomes. We showed that either targeted transcriptional activation or DNA demethylation can activate the silenced maternal SNRPN and downstream PWS transcripts. However, these two approaches function at unique regions, preferentially activating different transcript variants and involving distinct epigenetic reprogramming mechanisms. Remarkably, transient expression of the targeted demethylase leads to stable, long-term maternal SNRPN expression in PWS iPSCs. This work uncovers targeted epigenetic manipulations to reprogram a disease-associated imprinted locus and suggests possible therapeutic interventions.

Child characteristics associated with child quality of life and parenting stress in Angelman syndrome

BACKGROUND

Angelman syndrome (AS) is a rare neurodevelopmental disorder characterised by severe intellectual disability, movement disorder, epilepsy, sleeping problems, and behavioural issues. Little is known on child health-related quality of life (HRQoL) in AS. AS family studies have reported elevated parenting stress and a high impact of the child's syndrome on the parent. It is unclear which factors influence child HRQoL and parenting stress/impact in AS.

METHODS

We collected data prospectively through standardised clinical assessments of children with AS at the ENCORE Expertise centre for Angelman Syndrome at the Erasmus MC Sophia Children's Hospital. A linear regression analysis was conducted for the following outcome variables: (1) child HRQoL (Infant and Toddler Quality of Life Questionnaire); (2) the impact of the child's syndrome on the parent (Infant and Toddler Quality of Life Questionnaire); and (3) parenting stress (Parenting Stress Index). Predictor variables were child genotype, epilepsy, sleeping problems (Sleep Disturbance Scale for Children), cognitive developmental level (Bayley Cognition Scale), autistic features (Autism Diagnostic Observation Schedule) and emotional/behavioural problems (Child Behaviour Checklist). Covariates were sex, age and socio-economic status.

RESULTS

The study sample consisted of 73 children with AS, mean age = 9.1 years, range = 2-18 years. Emotional/behavioural problems were the strongest significant predictor of lowered child HRQoL. Internalising problems were driving this effect. In addition, having the deletion genotype and higher age was related to lower child HRQoL. Sleeping problems were related to a higher impact of the child's syndrome on the parent. Finally, emotional/behavioural problems were associated with higher parenting stress. Cognitive developmental level, autistic features and epilepsy were not a significant predictor of child HRQoL and parenting stress/impact.

CONCLUSIONS

These results suggest that interventions aimed at increasing child HRQoL and decreasing parenting stress/impact in AS should focus on child emotional/behavioural problems and sleeping problems, using a family-centred approach.

Evolution of the nervous system by acquisition of retrovirus-derived genes in mammals

In the course of evolution, the most highly developed organ is likely the brain, which has become more complex over time and acquired diverse forms and functions in different species. In particular, mammals have developed complex and high-functioning brains, and it has been reported that several genes derived from retroviruses were involved in mammalian brain evolution, that is, generating the complexity of the nervous system. Especially, the sushi-ichi-related retrotransposon homolog (SIRH)/retrotransposon gag-like (RTL) genes have been suggested to play a role in the evolutionary processes shaping brain morphology and function in mammals. Genetic mutation and altered expression of genes are linked to neurological disorders, highlighting how the acquisition of virus-derived genes in mammals has both driven brain evolution and imposed a susceptibility to diseases. This review provides an overview of the functions, diversity, evolution and diseases associated with SIRH/RTL genes in the nervous system. The contribution of retroviruses to brain evolution is an important research topic in evolutionary biology and neuroscience, and further insights are expected to be gained through future studies.

Genetic investigation of the ubiquitin-protein ligase E3A gene as putative target in Angelman syndrome

BACKGROUND

Angelman syndrome (AS) is caused by maternal chromosomal deletions, imprinting defects, paternal uniparental disomy involving chromosome 15 and the ubiquitin-protein ligase UBE3A gene mutations. However the genetic basis remains unclear for several patients.

AIM

To investigate the involvement of UBE3A gene in AS and identifying new potential genes using exome sequencing.

METHODS

We established a cohort study in 50 patients referred to Farhat Hached University Hospital between 2006 and 2021, with a strong suspicion of AS and absence of chromosomal aberrations. The UBE3A gene was screened for mutation detection. Two unrelated patients issued from consanguineous families were subjected to exome analysis.

RESULTS

We describe seven UBE3A variants among them 3 none previously described including intronic variants c.2220+14T>C (intron14), c.2507+43T>A (Exon15) and insertion in Exon7: c.30-47_30-46. The exome sequencing revealed 22 potential genes that could be involved in AS-like syndromes that should be investigated further.

CONCLUSION

Screening for UBE3A mutations in AS patients has been proven to be useful to confirm the diagnosis. Our exome findings could rise to new potential alternative target genes for genetic counseling.

Relationship between strabismus associated with Angelman syndrome and orbital anomaly

PURPOSE

To investigate the relationship between the details of strabismus and orbital abnormalities determined by ocular motility tests and orbital imaging examinations in 9 cases with Angelman syndrome (AS).

STUDY DESIGN

A retrospective, clinical report.

METHODS

The 9 AS cases (mean age at initial visit: 4.6 ± 8.0 years) were confirmed by genetic diagnosis of the chromosome 15q11-13 region. In all cases, axial imaging of the orbit in the transverse plane of the horizontal extraocular muscles was obtained. The opening angle between both lateral walls of the orbit (greater wing of sphenoid) was measured as the biorbital angle, and compared with the 95% confidence interval of the orbital angle in normal children.

RESULTS

All cases had exotropia with means of the distance and near of angle 32.2 prism diopters (Δ) ± 9.7Δ and 32.8Δ ± 8.3Δ. The mean of the biorbital angle was 107.7° ± 7.6°, greater than the biorbital angle of 94.3° ± 5.1° previously reported in 129 normal children (P < 0.0001, t-test). Except for one biorbital angle of 93° in the 25-year-old patient, all the biorbital angles in the 8 children were larger than the upper 95% confidence interval in normal children. Astigmatic and hyperopic ametropic amblyopia were detected in 3 cases and 1 case, respectively.

CONCLUSIONS

The frequency of exotropia in AS is higher than previously reported, with our results strongly suggesting that the enlarged biorbital angle is related to the pathogenesis of exotropia in AS.

"Heal the sick": Health status and caregiving during the 17th-18th century in Northern Italy (St. Biagio cemetery, Ravenna)

OBJECTIVE

The study of health-related care provision in archeology gives important indications on the culture and community organization of past populations. This study aims to assess the health status of the skeletal assemblage recovered from the burial site of St. Biagio (Ravenna, 17th-18th Centuries); next, we identified likely instances of need for and receipt of caregiving in response to the condition, to examine evidence of community attitudes toward disease and disability.

MATERIALS AND METHODS

The skeletal assemblage is composed of 133 individuals in a generally good state of preservation. Sex and age-at-death were estimated through classical anthropological methods. Health status was inferred through the biological index of frailty (BIF) and paleopathological analysis was performed through macroscopic and radiographic investigations. The "bioarcheology of care" approach was applied to individuals who showed evidence of impairment and disability.

RESULTS

The skeletal assemblage of St. Biagio was equally represented by males and females (50% males), with a higher percentage of adults (83.4%) than subadults (10.5%), and this is reflected in the high life expectancy at birth (40.3 years). No significant differences in health status emerged between age groups and sexes, with a generally high percentage of joint diseases, antemortem trauma, and infectious diseases. Evidence of care and compassion was found in some individuals with a high degree of impairment or disability, as in the case of probable Angelman syndrome.

DISCUSSION

This study provided important insights into the biological and social aspects of an Early Modern population in Northern Italy, showing that people with functional and/or visible abnormalities were probably cared for in life and were presumably considered full members of the society.

The 100 most-cited manuscripts in epilepsy epigenetics: a bibliometric analysis

PURPOSE

The top citation article reflects the developmental milestone of a given field. The purpose of this bibliometric analysis was to identify and assess the 100 most-cited (T100) articles on the epigenetics mechanism of epilepsy.

METHODS

The Web of Science Core Collection (WoSCC) database was used to investigate, and search terms related to epilepsy epigenetics were compiled. Results were ranked according to citation number. The publication year, citation density, authorship, journal, country, institution, manuscript type, theme, and clinical topics were further evaluated.

RESULTS

The Web of Science search returned a total of 1231 manuscripts. The number of citations for a manuscript ranges from 739 to 75. The greatest number of manuscripts in the top 100 was published in the Human Molecular Genetics and Neurobiology of Disease (n = 4). The journal with the highest 2021 impact factor was Nature Medicine (IF = 87.244). The most-cited paper by Aid et al. reported a new nomenclature for mouse and rat BDNF gene and its expression profiles. Most manuscripts were original articles (n = 69), of which 52 (75.4%) report findings of basic scientific work. The most prevalent theme was microRNA (n = 29), and the most popular clinical topic was temporal lobe epilepsy (n = 13).

CONCLUSIONS

The research on the epigenetics mechanism of epilepsy was in its infancy but full of potential. The developmental history and current achievements of hot themes, including microRNA, DNA methylation, and temporal lobe epilepsy, were overviewed. This bibliometric analysis provides useful information and insight for researchers when launching new projects.

A PSD-95 peptidomimetic mitigates neurological deficits in a mouse model of Angelman syndrome

Angelman Syndrome (AS) is a severe cognitive disorder caused by loss of neuronal expression of the E3 ubiquitin ligase UBE3A. In an AS mouse model, we previously reported a deficit in brain-derived neurotrophic factor (BDNF) signaling, and set out to develop a therapeutic that would restore normal signaling. We demonstrate that CN2097, a peptidomimetic compound that binds postsynaptic density protein-95 (PSD-95), a TrkB associated scaffolding protein, mitigates deficits in PLC-CaMKII and PI3K/mTOR pathways to restore synaptic plasticity and learning. Administration of CN2097 facilitated long-term potentiation (LTP) and corrected paired-pulse ratio. As the BDNF-mTORC1 pathway is critical for inhibition of autophagy, we investigated whether autophagy was disrupted in AS mice. We found aberrantly high autophagic activity attributable to a concomitant decrease in mTORC1 signaling, resulting in decreased levels of synaptic proteins, including Synapsin-1 and Shank3. CN2097 increased mTORC1 activity to normalize autophagy and restore hippocampal synaptic protein levels. Importantly, treatment mitigated cognitive and motor dysfunction. These findings support the use of neurotrophic therapeutics as a valuable approach for treating AS pathology.

Effects of valproate on seizure-like activity in Drosophila melanogaster with a knockdown of Ube3a in different neuronal populations as a model of Angelman Syndrome

Angelman Syndrome is a rare, genetically induced neurodevelopmental disorder. This disorder stems from a mutation or deletion of the maternal UBE3A gene. Characteristics of this disease include developmental delay, recurring seizures, and severe intellectual disabilities. We studied seizure activity in male Drosophila melanogaster with a knockdown of Ube3a in different neuronal populations (GABAergic, glutamatergic, mushroom body, and all neurons) and investigated the effects of the antiseizure medication (ASM) on seizure-like activity. Epileptiform activity was monitored in individual fruit flies using imaging chambers and mechanically induced seizures using a vortex assay. A positive control was also used: eas (easily shocked seizure phenotype). Seizure activity was analyzed for sums of seizure durations, number of seizures, and total time to return to normal activity. Ube3a knockdowns in GABAergic neurons elicited more seizure-like episodes than knockdowns in glutamatergic neurons and were on par with the positive control group and those with knockdowns in the mushroom bodies. We have established a method whereby valproate could be administered through food rather than through injections to effectively treat epileptiform activity. We demonstrated that if Ube3a is not knocked down pan-neuronally, Angelman Syndrome seizure-like activity can be studied using Drosophila melanogaster and therefore allows for high-throughput drug discovery.

Adult Gene Therapy for Epilepsy in a Model of Angelman Syndrome: Hope or Hype?

Antisense Oligonucleotide Therapy Rescues Disturbed Brain Rhythms and Sleep in Juvenile and Adult Mouse Models of Angelman Syndrome Lee D, Chen W, Kaku HN, Zhuo X, Chao ES, Soriano A, Kuncheria A, Flores S, Kim JH, Rivera A, Rigo F, Jafar-Nejad P, Beaudet AL, Caudill MS, Xue M. Elife . 20233;12:e81892. doi:10.7554/eLife.81892 UBE3A encodes ubiquitin protein ligase E3A, and in neurons its expression from the paternal allele is repressed by the UBE3A antisense transcript (UBE3A-ATS). This leaves neurons susceptible to loss-of-function of maternal UBE3A. Indeed, Angelman syndrome, a severe neurodevelopmental disorder, is caused by maternal UBE3A deficiency. A promising therapeutic approach to treating Angelman syndrome is to reactivate the intact paternal UBE3A by suppressing UBE3A-ATS. Prior studies show that many neurological phenotypes of maternal Ube3a knockout mice can only be rescued by reinstating Ube3a expression in early development, indicating a restricted therapeutic window for Angelman syndrome. Here, we report that reducing Ube3a-ATS by antisense oligonucleotides in juvenile or adult maternal Ube3a knockout mice rescues the abnormal electroencephalogram (EEG) rhythms and sleep disturbance, two prominent clinical features of Angelman syndrome. Importantly, the degree of phenotypic improvement correlates with the increase of Ube3a protein levels. These results indicate that the therapeutic window of genetic therapies for Angelman syndrome is broader than previously thought, and EEG power spectrum and sleep architecture should be used to evaluate the clinical efficacy of therapies.

Enabling endpoint development for interventional clinical trials in individuals with Angelman syndrome: a prospective, longitudinal, observational clinical study (FREESIAS)

BACKGROUND

Angelman syndrome (AS) is a rare neurodevelopmental disorder characterized by the absence of a functional UBE3A gene, which causes developmental, behavioral, and medical challenges. While currently untreatable, comprehensive data could help identify appropriate endpoints assessing meaningful improvements in clinical trials. Herein are reported the results from the FREESIAS study assessing the feasibility and utility of in-clinic and at-home measures of key AS symptoms.

METHODS

Fifty-five individuals with AS (aged < 5 years: n = 16, 5-12 years: n = 27, ≥ 18 years: n = 12; deletion genotype: n = 40, nondeletion genotype: n = 15) and 20 typically developing children (aged 1-12 years) were enrolled across six USA sites. Several clinical outcome assessments and digital health technologies were tested, together with overnight 19-lead electroencephalography (EEG) and additional polysomnography (PSG) sensors. Participants were assessed at baseline (Clinic Visit 1), 12 months later (Clinic Visit 2), and during intermittent home visits.

RESULTS

The participants achieved high completion rates for the clinical outcome assessments (adherence: 89-100% [Clinic Visit 1]; 76-91% [Clinic Visit 2]) and varied feasibility of and adherence to digital health technologies. The coronavirus disease 2019 (COVID-19) pandemic impacted participants' uptake of and/or adherence to some measures. It also potentially impacted the at-home PSG/EEG recordings, which were otherwise feasible. Participants achieved Bayley-III results comparable to the available natural history data, showing similar scores between individuals aged ≥ 18 and 5-12 years. Also, participants without a deletion generally scored higher on most clinical outcome assessments than participants with a deletion. Furthermore, the observed AS EEG phenotype of excess delta-band power was consistent with prior reports.

CONCLUSIONS

Although feasible clinical outcome assessments and digital health technologies are reported herein, further improved assessments of meaningful AS change are needed. Despite the COVID-19 pandemic, remote assessments facilitated high adherence levels and the results suggested that at-home PSG/EEG might be a feasible alternative to the in-clinic EEG assessments. Taken altogether, the combination of in-clinic/at-home clinical outcome assessments, digital health technologies, and PSG/EEG may improve protocol adherence, reduce patient burden, and optimize study outcomes in AS and other rare disease populations.

Angelman and Prader-Willi Syndromes: Sister Imprinting Disorders With High Complication Rates Following Spinal Deformity Surgery

We sought to examine the modern surgical treatment of spinal deformity associated with sister imprinting disorders, Prader-Willi syndrome (PWS) and Angelman syndrome (AS), with emphasis on the specific complications encountered in these patient populations. Fifteen patients with PWS and 5 patients with AS who underwent surgical intervention for spinal deformity between 2000 and 2018 were identified. Postoperative complications were classified using the modified Clavien-Dindo-Sink (CDS) system and further categorized into specific subtypes including excessive drainage, dehiscence, implant failure, infection, and delayed wound healing. Perioperative and final follow-up radiographic data were analyzed. Mean age at surgery was 12.9 years (range, 4-21 years) with mean follow-up of 46.1 months (range, 1-145 months). There were postoperative complications in 17 patients (85%). Ten major complications (CDS ≥ 3) occurred in 9 patients (45%). These included 5 infections requiring reoperation, 1 seroma requiring drainage, 2 severe cervical-thoracic deformities requiring reoperation, 1 implant failure requiring reoperation, and 1 death secondary to fungal sepsis and thromboembolic disease. Eight additional patients (40%) had minor complications (CDS 1 or 2). Eight intraoperative complications occurred in 5 patients (25%), including loss of neuromonitoring signals and cerebrospinal fluid leaks. Surgical intervention for scoliosis in PWS and AS continues to have high complication rates secondary to medical and behavioral comorbidities found in these patient populations. The exact etiology of the high complication rates encountered cannot be definitively stated, but both syndromes frequently present with a number of unique features that may predispose patients to develop surgical complications. [Orthopedics. 2023;46(4):e223-e229.].

Developing Angelman syndrome-specific clinician-reported and caregiver-reported measures to support holistic, patient-centered drug development

BACKGROUND

Angelman syndrome (AS) is a rare, heterogenous neurogenetic condition, which significantly impacts the lives of people with AS and their families. Valid and reliable measures reporting key symptoms and functional impairments of AS are required to support development of patient-centered therapies. We describe the development of clinician- and caregiver-reported, AS-specific Global Impression scales for incorporation into clinical trials. Best practice US Food and Drug Administration guidance for measure development was followed with input from expert clinicians, patient advocates, and caregivers during content generation and refinement.

RESULTS

Initial measurement domains for the Symptoms of AS-Clinician Global Impression (SAS-CGI) and the Caregiver-reported AS Scale (CASS) were identified from a conceptual disease model of AS symptoms and impacts, derived from interviews with caregivers and clinicians. Two rounds of cognitive debriefing (CD) interviews were performed; clinicians debriefed the SAS-CGI, with patient advocates and caregivers debriefing the CASS to ensure relevance and comprehension. Feedback was used to refine items and ensure wording was age-appropriate and captured AS-specific symptoms, as well as associated impacts and functional impairments. The SAS-CGI and CASS capture global assessments of seizures, sleep, maladaptive behaviors, expressive communication, fine and gross motor skills, cognition, and self-care, which were determined by clinicians, patient advocates, and caregivers to be the most challenging aspects of AS. Additionally, the measures include items for assessing overall AS symptoms and the meaningfulness of any change. In addition to ratings for severity, impact, and change, a notes field was included in the SAS-CGI to provide the rationale for the chosen rating. CD interviews confirmed the measures covered key concepts of AS from the perspective of clinicians and caregivers, and demonstrated that the measures' instructions, items, and response options were clear and appropriate. Interview feedback informed adjustments to the wording of the instructions and the items.

CONCLUSIONS

The SAS-CGI and CASS were designed to capture multiple AS symptoms, reflecting the heterogeneity and complexity of AS in children 1 to 12 years old. These clinical outcome assessments have been incorporated into AS clinical studies, which will allow for the evaluation of their psychometric properties and inform further refinements if needed.

Rates of Status Epilepticus and Sudden Unexplained Death in Epilepsy in People With Genetic Developmental and Epileptic Encephalopathies

BACKGROUND AND OBJECTIVES

The genetic developmental and epileptic encephalopathies (DEEs) comprise a large group of severe epilepsy syndromes, with a wide phenotypic spectrum. Currently, the rates of convulsive status epilepticus (CSE), nonconvulsive status epilepticus (NCSE), and sudden unexplained death in epilepsy (SUDEP) in these diseases are not well understood. We aimed to describe the proportions of patients with frequently observed genetic DEEs who developed CSE, NCSE, mortality, and SUDEP. Understanding the risks of these serious presentations in each genetic DEE will enable earlier diagnosis and appropriate management.

METHODS

In this retrospective analysis of patients with a genetic DEE, we estimated the proportions with CSE, NCSE, and SUDEP and the overall and SUDEP-specific mortality rates for each genetic diagnosis. We included patients with a pathogenic variant in the genes SCN1A, SCN2A, SCN8A, SYNGAP1, NEXMIF, CHD2, PCDH19, STXBP1, GRIN2A, KCNT1, and KCNQ2 and with Angelman syndrome (AS).

RESULTS

The cohort comprised 510 individuals with a genetic DEE, in whom we observed CSE in 47% and NCSE in 19%. The highest proportion of CSE occurred in patients with SCN1A-associated DEEs, including 181/203 (89%; 95% CI 84-93) patients with Dravet syndrome and 8/15 (53%; 95% CI 27-79) non-Dravet SCN1A-DEEs. CSE was also notable in patients with pathogenic variants in KCNT1 (6/10; 60%; 95% CI 26-88) and SCN2A (8/15; 53%; 95% CI 27-79). NCSE was common in patients with non-Dravet SCN1A-DEEs (8/15; 53%; 95% CI 27-79) and was notable in patients with CHD2-DEEs (6/14; 43%; 95% CI 18-71) and AS (6/19; 32%; 95% CI 13-57). There were 42/510 (8%) deaths among the cohort, producing a mortality rate of 6.1 per 1,000 person-years (95% CI 4.4-8.3). Cases of SUDEP accounted for 19/42 (48%) deaths. Four genes were associated with SUDEP: SCN1A, SCN2A, SCN8A, and STXBP1. The estimated SUDEP rate was 2.8 per 1,000 person-years (95% CI 1.6-4.3).

DISCUSSION

We showed that proportions of patients with CSE, NCSE, and SUDEP differ for commonly encountered genetic DEEs. The estimates for each genetic DEE studied will inform early diagnosis and management of status epilepticus and SUDEP and inform disease-specific counseling for patients and families in this high-risk group of conditions.

Quantitative EEG Analysis in Angelman Syndrome: Candidate Method for Assessing Therapeutics

The goal of these studies was to use quantitative (q)EEG techniques on data from children with Angelman syndrome (AS) using spectral power analysis, and to evaluate this as a potential biomarker and quantitative method to evaluate therapeutics. Although characteristic patterns are evident in visual inspection, using qEEG techniques has the potential to provide quantitative evidence of treatment efficacy. We first assessed spectral power from baseline EEG recordings collected from children with AS compared to age-matched neurotypical controls, which corroborated the previously reported finding of increased total power driven by elevated delta power in children with AS. We then retrospectively analyzed data collected during a clinical trial evaluating the safety and tolerability of minocycline (3 mg/kg/d) to compare pretreatment recordings from children with AS (4-12 years of age) to EEG activity at the end of treatment and following washout for EEG spectral power and epileptiform events. At baseline and during minocycline treatment, the AS subjects demonstrated increased delta power; however, following washout from minocycline treatment the AS subjects had significantly reduced EEG spectral power and epileptiform activity. Our findings support the use of qEEG analysis in evaluating AS and suggest that this technique may be useful to evaluate therapeutic efficacy in AS. Normalizing EEG power in AS therefore may become an important metric in screening therapeutics to gauge overall efficacy. As therapeutics transition from preclinical to clinical studies, it is vital to establish outcome measures that can quantitatively evaluate putative treatments for AS and neurological disorders with distinctive EEG patterns.

Angelman syndrome in two siblings: clinical case

Background. Angelman syndrome (AS) is rare genetic disease characterized by severe mental retardation, gross developmental speech delay, facial dysmorphia, disorders of motor activity, behavior and sleep, epileptic seizures manifestation. Pathology refers to diseases of genomic imprinting. There are four possible mechanisms of pathology development in Angelman syndrome: 15q11.2-q13 deletion on the chromosome 15 of maternal origin, mutation of the ubiquitin ligase (UBE3A) gene at the 15q11.2 locus on the chromosome 15 of maternal origin, uniparental disomy of the 15q11.2-q13 region of paternal origin, imprinting center defect.

Clinical case description. Clinical picture of Angelman syndrome in two twin sibs (boy E., girl V.) observed in Children’s City Clinical Hospital № 1 in Nizhny Novgorod is presented. Children from consecutive pregnancy with dichorionic-diamniotic twins; preterm birth at 30 weeks. There was burdened obstetric-biological and perinatal history due to the threatened miscarriage during this pregnancy and due to asphyxia of both children during delivery. The disease has classical course in both patients: static functions development delay, gross developmental speech and intellectual delay, behavioral and motor disorders (stereotypy, tremor, ataxia, episodes of unmotivated laughter, sleep disorders), presence of typical facial dysmorphia. This diagnosis was confirmed by the molecular genetic study (boy — mutation in exon 7 of the UBE3A gene, girl — mutations in exons 6 and 7 of the UBE3A gene). Features of epileptic seizure therapy in both patients are presented.

Conclusion. The presented clinical case demonstrates typical clinical picture of AS in two sibs confirmed by molecular genetic study. The therapy of this syndrome is very complicated. The described patients require constant anticonvulsant therapy, observation of neurologist, psychotherapist, working with speech pathologist. Complete correction of this syndrome is impossible. 

Social attention and social-emotional modulation of attention in Angelman syndrome: an eye-tracking study

Individuals with Angelman syndrome (AS) present with severe intellectual disability alongside a social phenotype characterised by social communication difficulties and an increased drive for social engagement. As the social phenotype in this condition is poorly understood, we examined patterns of social attention and social modulation of attention in AS. Twenty-four individuals with AS and twenty-one young children with similar mental age were shown videos featuring unfamiliar actors who performed simple actions across two conditions: a playful condition, in which the actor showed positive facial emotions, and a neutral condition, in which the actor showed a neutral facial expression. During the passive observation of the videos, participants' proportion of time spent watching the two areas of interest (faces and actions) was examined using eye-tracking technology. We found that the playful condition elicited increased proportion of fixations duration to the actor's face compared to the neutral condition similarly across groups. Additionally, the proportion of fixations duration to the action area was similar across groups in the two conditions. However, children with AS looked towards the actor's face for a shorter duration compared to the comparison group across conditions. This pattern of similarities and differences provides novel insight on the complex social phenotype of children with AS.

Developmental Skills of Individuals with Angelman Syndrome Assessed Using the Bayley-III

We describe the development of 236 children with Angelman syndrome (AS) using the Bayley Scales of Infant and Toddler Development, Third Edition. Multilevel linear mixed modeling approaches were used to explore differences between molecular subtypes and over time. Individuals with AS continue to make slow gains in development through at least age 12 years of age at about 1-2 months/year based on age equivalent score and 1-16 growth score points/year depending on molecular subtype and domain. Children with a deletion have lower scores at baseline and slower rate of gaining skills while children with UBE3A variant subtype demonstrated higher scores as well as greater rates of skill attainment in all domains. The developmental profiles of UPD and ImpD were similar.

The accuracy of cell-free DNA screening for fetal segmental copy number variants: A systematic review and meta-analysis

BACKGROUND

The performance of cell-free DNA (cfDNA) screening for microscopic copy number variants (CNVs) is unclear.

OBJECTIVES

This was a systematic review and meta-analysis to investigate the sensitivity, specificity and positive predictive value (PPV) of cfDNA screening for CNVs.

SEARCH STRATEGY

Articles published in EMBASE, PubMed or Web of Science before November 2022 were screened for inclusion. This protocol was registered with PROSPERO (23 March 2021, CRD42021250849) prior to initiation.

SELECTION CRITERIA

Articles published in English, detailing diagnostic outcomes for at least 10 high-risk CNV results with cfDNA were considered for inclusion.

DATA COLLECTION AND ANALYSIS

The PPV was calculated and pooled with random-effects models for double-arcsine transformed proportions, using cases with diagnostic confirmation. Overall sensitivity, specificity and a summary receiver-operating characteristics (ROC) curve were calculated using bivariate models. The risk of bias was assessed using QUADAS-2.

MAIN RESULTS

In all, 63 articles were included in the final analysis, detailing 1 591 459 cfDNA results. The pooled PPV was 37.5% (95% confidence interval [CI] 30.6-44.8), with substantial statistical heterogeneity (I²  = 93.9%). Bivariate meta-analysis estimated sensitivity and specificity to be 77.4% (95% CI 65.7-86.0) and 99.4% (95% CI 98.0-99.8), respectively, with an area under the summary ROC curve of 0.947 (95% CI 0.776-0.984).

CONCLUSIONS

Approximately one-third of women who screen high-risk for CNVs with cfDNA will have an affected fetus. This value is of importance for screening counselling.

Typical and atypical neural mechanisms support spoken word processing in Angelman syndrome

Angelman syndrome (AS) is known to affect expressive and receptive communication abilities. This study examined individual differences in neural mechanisms underlying speech processing in children with AS (n = 24, M age = 10.01 years) and typical development (n = 30, M age = 10.82 years) using auditory event-related potentials during passive listening to common English words and novel pseudowords. A group of adults with AS (n = 7, M = 31.78 years) provided data about the upper developmental range. The typically developing group demonstrated the expected more negative amplitudes in response to words than pseudowords within 250-500 ms after stimulus onset at the left temporal scalp region. Children and adults with AS exhibited a similar left-lateralized pattern of word-pseudoword differentiation at temporal and parietal regions, but not the midline parietal memory response for known words observed in the typically developing group, suggesting typical-like word-pseudoword differentiation along with possible alterations in the automatic recall of word meaning. These results have important implications for understanding receptive and expressive communication processes in AS and support the use of auditory neural responses for characterizing individual differences in neurodevelopmental disorders with limited speech.

Spoken language comprehension in children and adults with Angelman Syndrome

INTRODUCTION

Objective evaluation of receptive communication abilities in nonspeaking individuals using standardized behavioral measures can be complicated by co-occurring intellectual disabilities and motor difficulties. Eye tracking during listening may offer an informative complementary approach to directly evaluate receptive language skills.

METHOD

This study examined feasibility of eye gaze measures as an index of spoken language comprehension in nonspeaking children and adults with Angelman syndrome (AS; n = 23) using a looking-while-listening procedure. Typically developing children (n = 34) provided a reference data set. Primary caregivers of participants with AS completed standardized informant reports (MacArthur-Bates Communicative Development Inventory: Words and Gestures; Vineland Adaptive Behavior Scales-3; Aberrant Behavior Checklist-2) to characterize communicative skills and general adaptive functioning.

RESULTS

Gaze data in participants with AS, particularly in the individuals reported by caregivers to have larger receptive vocabularies and stronger adaptive communicative functioning, demonstrated the expected pattern of comprehension reflected by the increased probability of looks to the target images after vs. before they were named in a spoken sentence. However, processing speed (gaze reaction time) was significantly slower in participants with AS than in the typically developing group.

CONCLUSIONS

Gaze-based paradigms could be an informative measure of receptive communication processes in participants who are unable to complete traditional standardized behavioral assessments.

Telehealth Training in Naturalistic Communication Intervention for Mothers of Children with Angelman Syndrome

Objectives 

Young children with Angelman syndrome have significant delays in expressive communication. Parents of children with Angelman syndrome require training to support their child's communication development. Unfortunately, parent training focused on the needs of families of children with rare genetic syndromes is unavailable to many families. The purpose of this study was to evaluate a telehealth parent training program on naturalistic communication intervention for young children with Angelman syndrome.

Methods

Using two single-case multiple baseline designs across a total of six parent-child dyads, we evaluated the effects of a telehealth parent training program on parent implementation fidelity of a naturalistic communication intervention, child communication, and child engagement.

Results

With the telehealth parent training program, parent implementation fidelity of naturalistic communication intervention improved, maintained and generalized to untrained home routines. Small effects on child communication and engagement were observed during the program.

Conclusions

Parents of children with Angelman syndrome were successfully taught via telehealth to implement a naturalistic communication intervention with their child at home. Additional research is needed to promote positive child communication outcomes through parent-mediated intervention.

Generation and Characterization of a Novel Angelman Syndrome Mouse Model with a Full Deletion of the Ube3a Gene

Angelman syndrome (AS) is a neurodevelopmental disorder caused by deficits in maternally inherited UBE3A. The disease is characterized by intellectual disability, impaired motor skills, and behavioral deficits, including increased anxiety and autism spectrum disorder features. The mouse models used so far in AS research recapitulate most of the cardinal AS characteristics. However, they do not mimic the situation found in the majority of AS patients who have a large deletion spanning 4–6 Mb. There is also a large variability in phenotypes reported in the available models, which altogether limits development of therapeutics. Therefore, we have generated a mouse model in which the Ube3a gene is deleted entirely from the 5′ UTR to the 3′ UTR of mouse Ube3a isoform 2, resulting in a deletion of 76 kb. To investigate its phenotypic suitability as a model for AS, we employed a battery of behavioral tests directed to reveal AS pathology and to find out whether this model better mirrors AS development compared to other available models. We found that the maternally inherited Ube3a-deficient line exhibits robust motor dysfunction, as seen in the rotarod and DigiGait tests, and displays abnormalities in additional behavioral paradigms, including reduced nest building and hypoactivity, although no apparent cognitive phenotype was observed in the Barnes maze and novel object recognition tests. The AS mice did, however, underperform in more complex cognition tasks, such as place reversal in the IntelliCage system, and exhibited a different circadian rhythm activity pattern. We show that the novel UBE3A-deficient model, based on a whole-gene deletion, is suitable for AS research, as it recapitulates important phenotypes characteristic of AS. This new mouse model provides complementary possibilities to study the Ube3a gene and its function in health and disease as well as possible therapeutic interventions to restore function.

Relationships between challenging behavior and gastrointestinal symptoms, sleep problems, and internalizing and externalizing symptoms in children and adolescents with Angelman syndrome

BACKGROUND

Angelman syndrome (AS), is a rare genetic disorder. This study investigated the relationship between parent-reported comorbid symptoms including gastrointestinal symptoms, sleep problems, internalizing symptoms, and behavior problems in children and adolescents with AS.

METHOD

Parents of 98 children and adolescents with AS completed the Gastrointestinal Symptom Inventory, Children's Sleep Habits Questionnaire, Child Behavior Checklist, Social Communication Questionnaire, and the Behavior Problem Inventory-Short Form. Data were analyzed using descriptive statistics, Pearson's correlation coefficients, and hierarchical multiple regressions.

RESULTS

There was a high frequency of GI symptoms (99%), sleep problems (95.9%), challenging behavior (98%), internalizing symptoms (38%), and 72.4% of children and adolescents presented with ASD symptoms. Self-injurious behavior (SIB), aggressive/destructive behavior, and the frequency of stereotyped behavior positively correlated with GI symptoms and sleep problems and it was moderately negatively associated with age. Internalizing symptoms and age were positively associated with SIB. Aggression was significantly related to gender, but not the presence of ASD symptoms.

CONCLUSIONS

Findings highlight the relationships between comorbid conditions. They may lead to a deeper understanding of how comorbidities present in children and adolescents with Angelman Syndrome.

Feasibility of wearable technology for 'real-world' gait analysis in children with Prader-Willi and Angelman syndromes

BACKGROUND

Prader-Willi syndrome (PWS) and Angelman syndrome (AS) are neurodevelopmental disorders in need of innovative 'real-world' outcome measures to evaluate treatment effects. Instrumented gait analysis (IGA) using wearable technology offers a potentially feasible solution to measure "real-world' neurological and motor dysfunction in these groups.

METHODS

Children (50% female; 6-16 years) diagnosed with PWS (n = 9) and AS (n = 5) completed 'real-world' IGA assessments using the Physilog®5 wearable. PWS participants completed a laboratory assessment and a 'real-world' long walk. The AS group completed 'real-world' caregiver-assisted assessments. Mean and variability results for stride time, cadence, stance percentage (%) and stride length were extracted and compared across three different data reduction protocols.

RESULTS

The wearables approach was found to be feasible, with all participants able to complete at least one assessment. This study also demonstrated significant agreement, using Lin's concordance correlation coefficient (CCC), between laboratory and 'real-world' assessments in the PWS group for mean stride length, mean stance % and stance % CV (n = 7, CCC: 0.782-0.847, P = 0.011-0.009).

CONCLUSION

'Real-world' gait analysis using the Physilog®5 wearable was feasible to efficiently assess neurological and motor dysfunction in children affected with PWS and AS.

Improving Gene Therapy for Angelman Syndrome with Secreted Human UBE3A

The rare genetic neurodevelopmental disease Angelman syndrome (AS) is caused by the loss of function of UBE3A, a ubiquitin ligase. The disease results in a lifetime of severe symptoms, including intellectual disability and motor impairments for which there are no effective treatments. One avenue of treatment for AS is the use of gene therapy to reintroduce a functional copy of the UBE3A gene. Our group had previously shown that recombinant adeno-associated virus (rAAV) expressing mouse Ube3a could rescue deficits in a mouse model of AS. Here, we expand on this work and show that this approach could be successfully replicated in a second AS model using the human UBE3A gene. Furthermore, we address the challenge of limited vector distribution in the brain by developing a novel modified form of UBE3A. This modified protein, termed STUB, was designed with a secretion signal and a cell-penetrating peptide. This allowed transduced cells to act as factories for the production of UBE3A protein that could be taken up by neighboring non-transduced cells, thus increasing the number of neurons receiving the therapeutic protein. Combining this construct with intracerebroventricular injections to maximize rAAV distribution within the brain, we demonstrate that this novel approach improves the recovery of behavioral and electrophysiological deficits in the AS rat model. More importantly, a comparison of rAAV-STUB to a rAAV expressing the normal human UBE3A gene showed that STUB was a more effective therapeutic. These data suggest that rAAV-STUB is a new potential approach for the treatment of AS.

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.

The behavioural phenotype of SATB2-associated syndrome: a within-group and cross-syndrome analysis

Background

SATB2-associated syndrome (SAS) is a multisystem neurodevelopmental disorder characterised by intellectual disability, speech delay, and craniofacial anomalies. Although the clinical presentation of SAS is well-delineated, behaviours associated with SAS are less well-defined. Given the varied social profile reported in SAS of a ‘jovial’ predisposition and autistic behaviours, there may be phenotypic overlap with both Angelman syndrome (AS) and non-syndromal autism. This study aimed to describe behaviours in SAS in relation to chronological age and level of ability and contrast aspects of the behavioural phenotype with AS and non-syndromal autism.

Methods

Informant report questionnaire measures of behaviour, emotion, and autism characteristics were completed for 81 individuals with SAS (aged 1–36 years; 43 male). Within-group associations were analysed, and categorical data were compared between pre-school (1–5 years), school-age (6–15 years), and adolescent and adult SAS sub-groups (16 years and over). Cross-syndrome subscale and item-level analyses were conducted for 63 individuals with SAS (aged 1–27 years; 31 male), who were matched according to age and level of ability to 63 individuals with AS (aged 2–25 years; 32 male) and 63 individuals with non-syndromal autism (aged 3–26 years; 53 male).

Results

In SAS, higher rates of overactivity were moderately associated with lower self-help ability, and higher general anxiety scores were reported for males compared with females. Cross-syndrome subscale analyses uncovered several significant differences (p < .01), with comparatively low rates of stereotyped behaviour, overactivity, insistence on sameness and positive affect, and comparatively greater interest and pleasure and compulsive behaviour in individuals with SAS. Item-level analyses revealed a distinct profile of repetitive and autistic behaviours.

Limitations

Developmental analysis was based on a cross-sectional rather than a longitudinal research design, the contribution of pain and sleep to behaviour was not explored, and molecular genetic testing to determine genotype–phenotype behavioural relationships was not possible.

Conclusions

This study highlights the importance of behavioural comparisons to well-delineated groups and the utility of fine-grained item-level analyses to elucidate aspects of behaviour that might be syndrome related or shared across neurodevelopmental disorders. Future research is needed to further describe the distinctive repetitive and autistic behavioural phenotype in SAS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s11689-022-09426-0.

The role of whole exome sequencing in the UBE3A point mutation of Angelman Syndrome: A case report

INTRODUCTION

Angelman Syndrome (AS) is a rare disorder with a relatively well-defined phenotype caused by lack of expression of the maternally inherited ubiquitin-protein ligase E3A (UBE3A) gene in the brain. This article describes the role of genetic testing using whole-exome sequencing (WES) in detecting rare AS variants, a point mutation in the UBE3A gene.

CASE PRESENTATION

We describe a rarely reported clinical presentation of AS in a two year and ten months old girl with severe developmental delay, movement and balance disorder, frequent smiling, apparent happy demeanor, speech impairment, absence of seizure, lack of sleep, and abnormal food-related behavior. Physical examination showed microcephaly, with facial characteristics of AS, ataxia gait, and truncal hypotonia. The electroencephalogram showed medium amplitude rhythmic 2-3c/s. Brain Magnetic Resonance Imaging revealed microcephaly, corpus callosum dysgenesis, and heterotopia grey matter on the bilateral lateral ventricle. WES was conducted to search pathogenic variants and showed a heterozygous mutation in exon 9 of the UBE3A gene, c.1513C > T (p.Arg505Ter).

CONCLUSION

Angelman syndrome is a neurodevelopmental disorder that has several underlying genetic etiologies. WES could detect a rare variant of Angelman syndrome, identified as the point mutation of the UBE3A gene, which cannot be seen with other modalities.

Clinical Characterization of Epilepsy in Children With Angelman Syndrome

BACKGROUND

Epilepsy is highly prevalent in children with Angelman syndrome (AS), and its detailed characterization and relationship to the genotype (deletion vs nondeletion) is important both for medical practice and for clinical trial design.

METHODS AND MATERIALS

We retrospectively analyzed the main clinical features of epilepsy in 265 children with AS who were enrolled in the AS Natural History Study, a multicenter, observational study conducted at six centers in the United States. Participants were prospectively followed up and classified by genotype.

RESULTS

Epilepsy was reported in a greater proportion of individuals with a deletion than a nondeletion genotype (171 of 187 [91%] vs. 48 of 78 [61%], P < 0.001). Compared with participants with a nondeletion genotype, those with deletions were younger at the time of the first seizure (age: median [95% confidence interval]: 24 [21-24] months vs. 57 [36-85] months, P < 0.001) and had a higher prevalence of generalized motor seizures. Hospitalization following a seizure was reported in more children with a deletion than a nondeletion genotype (92 of 171 [54%] vs. 17 of 48 [36%], P = 0.04). The overall prevalence of absence seizures was not significantly different between genotype groups. Forty-six percent (102/219) of the individuals reporting epilepsy were diagnosed with AS concurrently or after their first seizure.

CONCLUSIONS

Significant differences exist in the clinical expression of epilepsy in AS according to the underlying genotype, with earlier age of onset and more severe epilepsy in individuals with AS due to a chromosome 15 deletion.

Investigation of age-related facial variation among Angelman syndrome patients

Angelman syndrome (AS) is one of the common genetic disorders that could emerge either from a 15q11-q13 deletion or paternal uniparental disomy (UPD) or imprinting or UBE3A mutations. AS comes with various behavioral and phenotypic variability, but the acquisition of subjects for experiment and automating the landmarking process to characterize facial morphology for Angelman syndrome variation investigation are common challenges. By automatically detecting and annotating subject faces, we collected 83 landmarks and 10 anthropometric linear distances were measured from 17 selected anatomical landmarks to account for shape variability. Statistical analyses were performed on the extracted data to investigate facial variation in each age group. There is a correspondence in the results achieved by relative warp (RW) of the principal component (PC) and the thin-plate spline (TPS) interpolation. The group is highly discriminated and the pattern of shape variability is higher in children than other groups when judged by the anthropometric measurement and principal component.

Deleting a UBE3A substrate rescues impaired hippocampal physiology and learning in Angelman syndrome mice

In humans, loss-of-function mutations in the UBE3A gene lead to the neurodevelopmental disorder Angelman syndrome (AS). AS patients have severe impairments in speech, learning and memory, and motor coordination, for which there is currently no treatment. In addition, UBE3A is duplicated in > 1-2% of patients with autism spectrum disorders-a further indication of the significant role it plays in brain development. Altered expression of UBE3A, an E3 ubiquitin ligase, is hypothesized to lead to impaired levels of its target proteins, but identifying the contribution of individual UBE3A targets to UBE3A-dependent deficits remains of critical importance. Ephexin5 is a putative UBE3A substrate that has restricted expression early in development, regulates synapse formation during hippocampal development, and is abnormally elevated in AS mice, modeled by maternally-derived Ube3a gene deletion. Here, we report that Ephexin5 can be directly ubiquitylated by UBE3A. Furthermore, removing Ephexin5 from AS mice specifically rescued hippocampus-dependent behaviors, CA1 physiology, and deficits in dendritic spine number. Our findings identify Ephexin5 as a key driver of hippocampal dysfunction and related behavioral deficits in AS mouse models. These results demonstrate the exciting potential of targeting Ephexin5, and possibly other UBE3A substrates, to improve symptoms of AS and other UBE3A-related developmental disorders.

Electrophysiological Characterization of Regular and Burst Firing Pyramidal Neurons of the Dorsal Subiculum in an Angelman Syndrome Mouse Model

Angelman syndrome (AS) is a debilitating neurogenetic disorder characterized by severe developmental delay, speech impairment, gait ataxia, sleep disturbances, epilepsy, and a unique behavioral phenotype. AS is caused by a microdeletion or mutation in the maternal 15q11-q13 chromosome region containing UBE3A gene. The hippocampus is one of the important brain regions affected in AS mice leading to substantial hippocampal-dependent cognitive and behavioral deficits. Recent studies have suggested an abnormal increase in the α1-Na/K-ATPase (α1-NaKA) in AS mice as the precipitating factor leading to the hippocampal deficits. A subsequent study showed that the hippocampal-dependent behavioral deficits occur as a result of altered calcium (Ca⁺²) dynamics in the CA1 pyramidal neurons (PNs) caused by the elevated α1-NaKA expression levels in the AS mice. Nonetheless, a causal link between hippocampal deficits and major behavioral phenotypes in AS is still obscure. Subiculum, a region adjacent to the hippocampal CA1 is the major output source of the hippocampus and plays an important role in the transfer of information from the CA1 region to the cortical areas. However, in spite of the robust hippocampal deficits and several known electrophysiological alterations in multiple brain regions in AS mice, the neuronal properties of the subicular neurons were never investigated in these mice. Additionally, subicular function is also implied in many neuropsychiatric disorders such as autism, schizophrenia, Alzheimer’s disease, and epilepsy that share some common features with AS. Therefore, given the importance of the subiculum in these neuropsychiatric disorders and the altered electrophysiological properties of the hippocampal CA1 PNs projecting to the subiculum, we sought to examine the subicular PNs. We performed whole-cell recordings from dorsal subiculum of both WT and AS mice and found three distinct populations of PNs based on their ability to fire bursts or single action potentials following somatic current injection: strong bursting, weak bursting, and regular firing neurons. We found no overall differences in the distribution of these different subicular PN populations among AS and WT controls. However, the different cell types showed distinct alterations in their intrinsic membrane properties. Further, none of these populations were altered in their excitatory synaptic properties. Altogether, our study characterized the different subtypes of PNs in the subicular region of an AS mouse model.

Secreted retrovirus-like GAG-domain-containing protein PEG10 is regulated by UBE3A and is involved in Angelman syndrome pathophysiology

Angelman syndrome (AS) is a neurodevelopmental disorder caused by the loss of maternal UBE3A, a ubiquitin protein ligase E3A. Here, we study neurons derived from patients with AS and neurotypical individuals, and reciprocally modulate UBE3A using antisense oligonucleotides. Unbiased proteomics reveal proteins that are regulated by UBE3A in a disease-specific manner, including PEG10, a retrotransposon-derived GAG protein. PEG10 protein increase, but not RNA, is dependent on UBE3A and proteasome function. PEG10 binds to both RNA and ataxia-associated proteins (ATXN2 and ATXN10), localizes to stress granules, and is secreted in extracellular vesicles, modulating vesicle content. Rescue of AS patient-derived neurons by UBE3A reinstatement or PEG10 reduction reveals similarity in transcriptome changes. Overexpression of PEG10 during mouse brain development alters neuronal migration, suggesting that it can affect brain development. These findings imply that PEG10 is a secreted human UBE3A target involved in AS pathophysiology.

A Comprehensive Approach to Rehabilitation Interventions in Patients with Angelman Syndrome: A Systematic Review of the Literature

Angelman syndrome is a rare genetic disease affecting the central nervous system and neurobehavioral development causing severe mental, linguistic, and physical disabilities. The purpose of this review was to analyze the most recent evidence regarding the rehabilitation of subjects affected by this syndrome. The review was carried out in accordance with the preferred reporting items for systematic reviews and meta-analyses. A total of 3661 studies were identified in the databases. Once the inclusion/exclusion criteria were applied, 15 studies were considered for the paper's preparation. The level of evidence of the studies was established according to the criteria of the Oxford Center for Evidence-Based Medicine-Levels of Evidence. From the selected studies, five rehabilitative approaches emerged: physiotherapy, applied behavioral analysis, toilet training, microswitch-cluster technology, and augmentative and alternative communication. Although the studies did not have a high level of evidence, the reported results appear to be encouraging and pave the way for further studies. It seems that individualized and multidisciplinary rehabilitation interventions help to improve patients' autonomy and quality of life. In some studies, the caregivers' role was fundamental to identify preferences and long-term improvements. Further studies on larger populations and with better methodological quality are needed to confirm the results.

Dopaminergic Dysregulation in Syndromic Autism Spectrum Disorders: Insights From Genetic Mouse Models

Autism spectrum disorder (ASD) is a neurodevelopmental disorder defined by altered social interaction and communication, and repetitive, restricted, inflexible behaviors. Approximately 1.5-2% of the general population meet the diagnostic criteria for ASD and several brain regions including the cortex, amygdala, cerebellum and basal ganglia have been implicated in ASD pathophysiology. The midbrain dopamine system is an important modulator of cellular and synaptic function in multiple ASD-implicated brain regions via anatomically and functionally distinct dopaminergic projections. The dopamine hypothesis of ASD postulates that dysregulation of dopaminergic projection pathways could contribute to the behavioral manifestations of ASD, including altered reward value of social stimuli, changes in sensorimotor processing, and motor stereotypies. In this review, we examine the support for the idea that cell-autonomous changes in dopaminergic function are a core component of ASD pathophysiology. We discuss the human literature supporting the involvement of altered dopamine signaling in ASD including genetic, brain imaging and pharmacologic studies. We then focus on genetic mouse models of syndromic neurodevelopmental disorders in which single gene mutations lead to increased risk for ASD. We highlight studies that have directly examined dopamine neuron number, morphology, physiology, or output in these models. Overall, we find considerable support for the idea that the dopamine system may be dysregulated in syndromic ASDs; however, there does not appear to be a consistent signature and some models show increased dopaminergic function, while others have deficient dopamine signaling. We conclude that dopamine dysregulation is common in syndromic forms of ASD but that the specific changes may be unique to each genetic disorder and may not account for the full spectrum of ASD-related manifestations.

The adaptive functioning profile of Pitt-Hopkins syndrome

BACKGROUND

There are few cohort studies describing the adaptive functioning profile for Pitt-Hopkins syndrome (PTHS). In this study we examine the adaptive functioning profile for PTHS and compare it to Angelman syndrome (AS).

METHOD

Caregivers of 14 individuals with PTHS, 33 with deletion AS and 23 with non-deletion AS, completed the Vineland Adaptive Behavior Scales-II.

RESULTS

The profile of adaptive functioning in PTHS was characterised by strengths in socialisation, followed by motor skills, communication then daily living skills. The PTHS group scored significantly lower than the non-deletion AS group on all domains except socialisation and significantly lower than the deletion AS group, for motor skills only.

CONCLUSIONS

An uneven adaptive behavior profile for individuals with PTHS mirrors that of AS, with implications for assessment and intervention.

Spread of X-chromosome inactivation into autosomal regions in patients with unbalanced X-autosome translocations and its phenotypic effects

Patients with unbalanced X-autosome translocations are rare and usually present a skewed X-chromosome inactivation (XCI) pattern, with the derivative chromosome being preferentially inactivated, and with a possible spread of XCI into the autosomal regions attached to it, which can inactivate autosomal genes and affect the patients' phenotype. We describe three patients carrying different unbalanced X-autosome translocations, confirmed by G-banding karyotype and array techniques. We analyzed their XCI pattern and inactivation spread into autosomal regions, through HUMARA, ZDHHC15 gene assay and the novel 5-ethynyl-2'-deoxyuridine (EdU) incorporation assay, and identified an extremely skewed XCI pattern toward the derivative chromosomes for all the patients, and a variable pattern of late-replication on the autosomal regions of the derivative chromosomes. All patients showed phenotypical overlap with patients presenting deletions of the autosomal late-replicating regions, suggesting that the inactivation of autosomal segments may be responsible for their phenotype. Our data highlight the importance of the XCI spread into autosomal regions for establishing the clinical picture in patients carrying unbalanced X-autosome translocations, and the incorporation of EdU as a novel and precise tool to evaluate the inactivation status in such patients.

Hip Dislocation After Correction for Scoliosis in an Adolescent with Angelman Syndrome: A Case Report

CASE

Although scoliosis is common in Angelman syndrome (AS), there are no reports of hip dislocation as a complication of scoliosis surgery. We experienced a case of hip dislocation after posterior spinal instrumentation and fusion from T4 to L5 because of scoliosis progression in an adolescent girl with AS. Postoperatively, posterior dislocation of the left hip occurred; after closed reduction, instability remained. Thus, periacetabular osteotomy was performed (left hip), with good clinical outcomes.

CONCLUSION

Especially in cases of abnormal muscle tone, a loss of spinal flexibility because of extensive spinal fixation may result in secondary pathologies of the hip joint.

Epigenetics of the developing and aging brain: Mechanisms that regulate onset and outcomes of brain reorganization

Brain development is a life-long process that encompasses several critical periods of transition, during which significant cognitive changes occur. Embryonic development, puberty, and reproductive senescence are all periods of transition that are hypersensitive to environmental factors. Rather than isolated episodes, each transition builds upon the last and is influenced by consequential changes that occur in the transition before it. Epigenetic marks, such as DNA methylation and histone modifications, provide mechanisms by which early events can influence development, cognition, and health outcomes. For example, parental environment influences imprinting patterns in gamete cells, which ultimately impacts gene expression in the embryo which may result in hypersensitivity to poor maternal nutrition during pregnancy, raising the risks for cognitive impairment later in life. This review explores how epigenetics induce and regulate critical periods, and also discusses how early environmental interactions prime a system towards a particular health outcome and influence susceptibility to disease or cognitive impairment throughout life.