Angelman syndrome in Hong Kong Chinese: A 20 years’ experience

Association between sleep disturbances and challenging behavior in children and adolescents with Angelman syndrome

Angelman Syndrome (AS) is a neurodevelopmental disorder with severe symptoms and associated comorbidities. It is caused by the inactivity or lack of the UBE3a gene. Symptoms of the syndrome include intellectual disability and developmental delay. The current study investigated sleep disturbances (SD) in children and adolescents with AS, associations between SD and possible predictors of SD. Variables examined included age, gender, newborn and infancy history, challenging behavior, type of therapy received, genetic type of AS, and seizures. The sample included data from 109 participants with a mean age of 8.21, accessed via the Global Angelman Syndrome Registry. Chi-square tests were carried out to assess the associations between the variables and a logistical regression was carried out to assess the possible predictors of SD. Associations were found between SD and certain repetitive behaviors: slapping walls, focal hand movements, and agitation at new situations. From these associations, a regression formed a predictive model for sleep disturbances. The findings of this research demonstrated the importance of investigating the relationship between sleep disturbances and challenging behavior in children and adolescents with AS and the need for further research in this area.

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.

Expanding deep phenotypic spectrum associated with atypical pathogenic structural variations overlapping 15q11-q13 imprinting region

BACKGROUND

The 15q11-q13 region is a genetic locus with genes subject to genomic imprinting, significantly influencing neurodevelopment. Genomic imprinting is an epigenetic phenomenon that causes differential gene expression based on the parent of origin. In most diploid organisms, gene expression typically involves an equal contribution from both maternal and paternal alleles, shaping the phenotype. Nevertheless, in mammals, including humans, mice, and marsupials, the functional equivalence of parental alleles is not universally maintained. Notably, during male and female gametogenesis, parental alleles may undergo differential marking or imprinting, thereby modifying gene expression without altering the underlying DNA sequence. Neurodevelopmental disorders, such as Prader-Willi syndrome (PWS) (resulting from the absence of paternally expressed genes in this region), Angelman syndrome (AS) (associated with the absence of the maternally expressed UBE3A gene), and 15q11-q13 duplication syndrome (resulting from the two common forms of duplications-either an extra isodicentric 15 chromosome or an interstitial 15 duplication), are the outcomes of genetic variations in this imprinting region.

METHODS

Conducted a genomic study to identify the frequency of pathogenic variants impacting the 15q11-q13 region in an ethnically homogenous population from Bangladesh. Screened all known disorders from the DECIPHER database and identified variant enrichment within this cohort. Using the Horizon analysis platform, performed enrichment analysis, requiring at least >60% overlap between a copy number variation and a disorder breakpoint. Deep clinical phenotyping was carried out through multiple examination sessions to evaluate a range of clinical symptoms.

RESULTS

This study included eight individuals with clinically suspected PWS/AS, all previously confirmed through chromosomal microarray analysis, which revealed chromosomal breakpoints within the 15q11-q13 region. Among this cohort, six cases (75%) exhibited variable lengths of deletions, whereas two cases (25%) showed duplications. These included one type 2 duplication, one larger atypical duplication, one shorter type 2 deletion, one larger type 1 deletion, and four cases with atypical deletions. Furthermore, thorough clinical assessments led to the diagnosis of four PWS patients, two AS patients, and two individuals with 15q11-q13 duplication syndrome.

CONCLUSION

Our deep phenotypic observations identified a spectrum of clinical features that overlap and are unique to PWS, AS, and Dup15q syndromes. Our findings establish genotype-phenotype correlation for patients impacted by variable structural variations within the 15q11-q13 region.

Impact of Deletion on Angelman Syndrome Phenotype Variability: Phenotype-Genotype Correlation in 97 Patients with Motor Developmental Delay

Angelman syndrome (AS) is a rare neurodevelopmental disorder due to genetic defects involving chromosome 15, known by intellectual disability, cognitive and behavioral disorders, ataxia, delayed motor development, and seizures. This study highlights the clinical spectrum and molecular research to establish the genotype-phenotype correlation in the pediatric Moroccan population. Methylation-specific-polymerase chain reaction (MS-PCR) is a primordial technique not only to identify the genetic mechanism of AS but also to characterize the different molecular classes induced in the appearance of the clinical symptoms. Patients with positive methylation profile were additionally studied by fluorescent in situ hybridization. Sequencing analysis of the UBE3A gene was performed for patients with negative MS-PCR. We used Fisher's test to assess differences in the distribution of features frequencies among the deletional and the nondeletional group. Statistical analysis was performed using R project. We identified from 97 patients diagnosed with AS, 14 (2.06%) had a classical AS phenotype, while 70 (84.5%) patients displayed a subset of consistent and frequent criteria. Development delay was shown severe in 63% and moderate in 37%. Nineteen out of 97 of them had MS-PCR positive in which 17 (89.47%) had 15q11-q13 deletion. Deletion patients presented a higher incidence of epileptic seizures ( p  = 0.04), ataxia ( p  = 0.0008), and abnormal electroencephalogram (EEG) profile ( p  = 0.003). We further found out a frameshift deletion located at exon 9 of the UBE3A gene discovered in a 5 years old patient. We report in this study the genotype-phenotype correlation using different molecular testing. Correlation analysis did not reveal any statistical differences in phenotypic dissimilarity between deletion and nondeletion groups for most clinical features, except the correlation was highly significant in the abnormal EEG. According to our findings, we recommend offering MS-PCR analysis to all patients with severe intellectual disability, developmental delay, speech impairment, happy demeanor, and hypopigmentation.

Stem cell models of Angelman syndrome

Angelman syndrome (AS) is an imprinted neurodevelopmental disorder that lacks a cure, characterized by developmental delay, intellectual impairment, seizures, ataxia, and paroxysmal laughter. The condition arises due to the loss of the maternally inherited copy of the UBE3A gene in neurons. The paternally inherited UBE3A allele is unable to compensate because it is silenced by the expression of an antisense transcript (UBE3A-ATS) on the paternal chromosome. UBE3A, encoding enigmatic E3 ubiquitin ligase variants, regulates target proteins by either modifying their properties/functions or leading them to degradation through the proteasome. Over time, animal models, particularly the Ube3a mat-/pat+ Knock-Out (KO) mice, have significantly contributed to our understanding of the molecular mechanisms underlying AS. However, a shift toward human pluripotent stem cell models (PSCs), such as human embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), has gained momentum. These stem cell models accurately capture human genetic and cellular characteristics, offering an alternative or a complement to animal experimentation. Human stem cells possess the remarkable ability to recapitulate neurogenesis and generate "brain-in-a-dish" models, making them valuable tools for studying neurodevelopmental disorders like AS. In this review, we provide an overview of the current state-of-the-art human stem cell models of AS and explore their potential to become the preclinical models of choice for drug screening and development, thus propelling AS therapeutic advancements and improving the lives of affected individuals.

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.

Current and emerging treatment options for Angelman syndrome

INTRODUCTION

Angelman syndrome (AS) is a neurodevelopmental disorder characterized by intellectual disability, limited expressive language, epilepsy, and motor impairment. Angelman syndrome is caused by haploinsufficiency of the UBE3A gene on the maternal copy of chromosome 15. There have been ongoing advances in the understanding of neurological, behavioral, and sleep-based problems and associated treatments for patients with AS. These results along with gene-based therapies entering into clinical development prompted this review.

AREAS COVERED

The authors summarize the research basis describing phenomenology of epilepsy and behavioral concerns such as hyperactivity behavior, aggression, self-injury, repetitive behavior, and sleep disorder. The evidence for recent treatment advances in these target symptom domains of concern is reviewed, and the potential for emerging gene therapy treatments is considered.

EXPERT OPINION

The prospect for emerging gene therapies means that increasing efforts should be directed toward the early identification of AS implemented equitably. Recent studies emphasize the important role of behavioral therapy in addressing mental health concerns such as aggression and disordered sleep.

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.

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.

Estimating the impact of Angelman syndrome on parental productivity in Australia using productivity-adjusted life years

BACKGROUND

Angelman syndrome (AS) is a rare genetic condition characterized by global developmental delay, including severe intellectual disability. The parents of persons with AS experience increased stress, anxiety, and depression. This impacts parents' career choices and productivity.

OBJECTIVE

To estimate, for the first time, the total productivity lost by the parents of persons with AS over a 10-year period in Australia and the corresponding cost to society.

METHODS

A cost-of-illness model with simulated follow-up over a 10-year period was developed, with 2019 as the baseline year, facilitated by a Markov chain of life tables. The prevalence of persons with AS and their parents, the productivity-adjusted life years (PALYs) lost by parents, and the cost to society were estimated. Key data were obtained from a prospective cohort of AS families, peer-reviewed literature, and publicly available sources.

RESULTS

The base-case productivity burden borne by the estimated 330 living parents of the 428 prevalent persons with AS totaled AUD$45.30 million, corresponding to a loss of 38.42% of PALYs per parent.

CONCLUSIONS

Caring for a child with AS has a significant impact on the productivity of affected parents, with a large associated impact on the broader Australian economy.

Laryngotracheal separation surgery in a patient with severe Angelman syndrome involving a 19.3 Mb deletion on 15q11.2-q14

A severe Angelman syndrome (AS) patient with a very large deletion (19.3 Mb) at 15q11.2-q14 required laryngotracheal separation, which is not a common surgery in AS. Comparative genomic hybridization-based microarrays can be useful to confirm deletion size and clinical severity.

An Analysis of Phenotype and Genotype in a Large Cohort of Chinese Children with Angelman Syndrome

Angelman syndrome (AS) is a neurodevelopmental genetic disorder, but there has been limited analysis of a large cohort of Chinese children with Angelman syndrome. This study aims to assess the phenotype and genotype of Chinese children with Angelman syndrome. We retrospectively analyzed data through a detailed online survey combined with an on-site study. Furthermore, phenotype analysis stratified by deletion and non-deletion groups was carried out. The responses of family members of 695 individuals with AS revealed that 577 patients (83.02%) had maternal deletions, 65 patients (9.35%) carried UBE3A mutations, 31 (4.46%) patients had UPD15pat (one patient with UPD15pat constituted by a mosaic), 10 patients (1.44%) had imprinting defects and 12 (1.58%) patients only showed abnormal methylation without further detection. We identified 50 different pathogenic variants in this cohort, although 18 of these variants were unreported. Recurrent variant c.2507_2510del (p.K836Rfs*4) was found in 7 patients. In the deletion group, patients were diagnosed at an earlier age, had a more severe clinical phenotype, a higher rate of epilepsy with more multiple seizure types, and more frequently combined medication. Strabismus and sleep disturbances were both common in deletion and non-deletion groups. The top three resources invested in caring for AS children are: daily involvement in patient care, rehabilitation cost, and anti-epileptic treatment. Our study showed the genetic composition of Chinese children with 83.02% of maternal deletions, and the mutation spectrum for UBE3A variants was expanded. Developmental outcomes are associated with genotype, and this was confirmed by deletion patients having a worse clinical phenotype and complex epilepsy.

Pharmacotherapeutic management of seizures in patients with Angleman syndrome

Approximately 80-90% of patients with Angelman syndrome (AS) develop childhood-onset intractable seizures with major negative impact on the quality of life.Thus adequate management of seizures is the most critical priority to improve health-related quality of life in children with AS.

AREAS COVERED

The primary focus of the review is on pharmacotherapeutic management of seizures. The first part of the review briefly discusses epileptogenesis and polymorphic seizure phenotypes associated with AS to understand pharmacotherapeutic decision-making better. Next, the review explores individual antiseizure medicines (ASMs) and their potential therapeutic utility. Lastly, some future and emerging treatment options are discussed that can transform the management of seizures in patients with AS.

EXPERT OPINION

Evidence for treating seizures in AS mainly derives from low-quality studies. Levetiracetam and clobazam are the most commonly used ASMs. Although the potential utility of several other ASMs(valproate, topiramate, lamotrigine, ethosuximide, clonazepam) has been well documented for some time, the treatment landscape may rapidly evolve due to the availability of newer and better tolerated ASMs(cannabidiol oil, brivaracetam, perampanel). In addition, a better understanding of the underlying pathogenesis and the development of molecular therapeutics offer hope for precision therapies for seizures.

Epilepsy and Molecular Phenotype Affect the Neurodevelopment of Pediatric Angelman Syndrome Patients in China

OBJECTIVE

This study investigated the mental development of children with Angelman syndrome (AS) in China and evaluated the relationship between neurodevelopment and molecular subtype, age, epilepsy, and sex using the Chinese version of the Griffith Mental Development Scale (GMDS-C) to provide detailed baseline data regarding neurodevelopment with AS in China.

METHODS

Participants were recruited from the AS Natural History Study. The GMDS-C was used to evaluate all participants' mental age and developmental quotients. The general quotient (GQ) and quotients of five subscales (sports, personal-social, auditory language, eye-hand coordination, and comprehensive performance) were calculated.

RESULTS

A total of 119 children (average age: 42.12 months; range, 7.5-95.5 months) with a genetic diagnosis of AS were enrolled. The median GQ score of the GMDS was 29.6 points (95% confidence interval, 28.6-33.25). The children had relatively good locomotor and personal-social skills but poor language skills. Overall, 89% (106/119) had mental ages younger than 24 months for all five subscales. The non-deletion group (i.e., without deletion in chromosome 15q11-13) had higher GQs and locomotor, personal-social, and performance subscale quotients. The GQ was significantly different among the three age subgroups and significantly correlated with age. Compared with the non-epilepsy group, the epilepsy group had lower GQs and lower quotients for the locomotor, personal-social, speech, language, and eye-hand coordination subscales.

CONCLUSION

Children with AS in China experience severe neurodevelopmental deterioration. In addition to age, molecular subtypes and the onset of seizures may also correlate with these patients' intellectual development. The GMDS-C is an accurate tool that can assess the clinical characteristics of AS. The data of this study can be used as baseline data for clinical trials performed to evaluate drug development or other AS treatment development.

Electrophysiological Abnormalities in Angelman Syndrome Correlate With Symptom Severity

Background

Angelman syndrome (AS) is a rare neurodevelopmental disorder caused by the absence of functional UBE3A in neurons. Excess low-frequency oscillations as measured with electroencephalography (EEG) have been identified as a characteristic finding, but the relationship of this EEG finding to the symptomatology of AS and its significance in the pathophysiology of AS remain unknown.

Methods

We used correlations and machine learning to investigate the cross-sectional and longitudinal relationship between EEG spectral power and motor, cognitive, and language skills (Bayley Scales of Infant and Toddler Development, Third Edition); adaptive behavior (Vineland Adaptive Behavior Scales, Second Edition); AS-specific symptoms (AS Clinical Severity Scale); and the age of epilepsy onset in a large sample of children (age: 1–18 years) with AS due to a chromosomal deletion of 15q11-q13 (45 individuals with 72 visits).

Results

We found that after accounting for age differences, participants with stronger EEG delta-band abnormality had earlier onset of epilepsy and lower performance scores across symptom domains including cognitive, motor, and communication. Combing spatial and spectral information beyond the delta frequency band increased the cross-sectional association with clinical severity on average by approximately 45%. Furthermore, we found evidence for longitudinal correlations of EEG delta-band power within several performance domains, including the mean across Bayley Scales of Infant and Toddler Development, Third Edition, scores.

Conclusions

Our results show an association between EEG abnormalities and symptom severity in AS, underlining the significance of the former in the pathophysiology of AS. Furthermore, our work strengthens the rationale for using EEG as a biomarker in the development of treatments for AS, a concept that may apply more generally to neurodevelopmental disorders.

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.

Case Report: An Atypical Angelman Syndrome Case With Obesity and Fulfilled Autism Spectrum Disorder Identified by Microarray

Autism spectrum disorder (ASD) is a group of neurodevelopmental disorders which are etiologically heterogeneous. Chromosomal microarray is now recommended as the first-tier clinical diagnostic test for ASD. We performed chromosomal microarray in 16 Thai patients with ASD using an Illumina HumanCytoSNP-12 v2.1 array and found one case with uniparental disomy (UPD) of chromosome 15. Methylation-specific PCR showed abnormal methylation of the maternal SNRPN allele. Haplotype analysis revealed that the patient had received both chromosomes 15 from his father. These results were consistent with Angelman syndrome. However, his clinical features had no clinical significance for classic Angelman syndrome. He had first presented at the pediatric clinic with no speech, poor social interaction skills and repetitive behaviors consistent with ASD based on the DSM-IV criteria at 2 years of age and later confirmed by ADOS at 5 years of age. He was strikingly overweight but had no dysmorphic facies, seizures nor ataxia and was diagnosed as non-syndromic ASD, a diagnosis which was believed until at 10 years of age, his DNA was included for analysis in this current cohort study. Our findings suggest that ASD patients with unknown etiology should be considered for methylation-specific PCR testing for Angelman syndrome where chromosomal microarray is not available. In the study, we also review the clinical features of Angelman syndrome caused by UPD and the frequency of ASD in individuals with Angelman syndrome.

Evaluating Sleep Disturbances in Children With Rare Genetic Neurodevelopmental Syndromes

BACKGROUND

Adequate sleep is important for proper neurodevelopment and positive health outcomes. Sleep disturbances are more prevalent in children with genetically determined neurodevelopmental syndromes compared with typically developing counterparts. We characterize sleep behavior in Rett (RTT), Angelman (AS), and Prader-Willi (PWS) syndromes to identify effective approaches for treating sleep problems in these populations. We compared sleep-related symptoms across individuals with these different syndromes with each other, and with typically developing controls.

METHODS

Children were recruited from the Rare Diseases Clinical Research Network consortium registries; unaffected siblings were enrolled as related controls. For each participant, a parent completed multiple sleep questionnaires including Pediatric Sleep Questionnaire (Sleep-Disordered Breathing), Children's Sleep Habits Questionnaire (CSHQ), and Pediatric Daytime Sleepiness Scale.

RESULTS

Sleep data were analyzed from 714 participants, aged two to 18 years. Young children with AS had more reported sleep problems than children with RTT or PWS. Older children with RTT had more reported daytime sleepiness than those with AS or PWS. Finally, all individuals with RTT had more evidence of sleep-disordered breathing when compared with individuals with PWS. Notably, typically developing siblings were also reported to have sleep problems, except for sleep-related breathing disturbances, which were associated with each of the genetic syndromes.

CONCLUSIONS

Individuals with RTT, AS, and PWS frequently experience sleep problems, including sleep-disordered breathing. Screening for sleep problems in individuals with these and other neurogenetic disorders should be included in clinical assessment and managements. These data may also be useful in developing treatment strategies and in clinical trials.

Genotype-Phenotype Correlations in Angelman Syndrome

Angelman syndrome (AS) is a rare neurodevelopmental disease that is caused by the loss of function of the maternal copy of ubiquitin-protein ligase E3A (UBE3A) on the chromosome 15q11-13 region. AS is characterized by global developmental delay, severe intellectual disability, lack of speech, happy disposition, ataxia, epilepsy, and distinct behavioral profile. There are four molecular mechanisms of etiology: maternal deletion of chromosome 15q11-q13, paternal uniparental disomy of chromosome 15q11-q13, imprinting defects, and maternally inherited UBE3A mutations. Different genetic types may show different phenotypes in performance, seizure, behavior, sleep, and other aspects. AS caused by maternal deletion of 15q11-13 appears to have worse development, cognitive skills, albinism, ataxia, and more autistic features than those of other genotypes. Children with a UBE3A mutation have less severe phenotypes and a nearly normal development quotient. In this review, we proposed to review genotype-phenotype correlations based on different genotypes. Understanding the pathophysiology of the different genotypes and the genotype-phenotype correlations will offer an opportunity for individualized treatment and genetic counseling. Genotype-phenotype correlations based on larger data should be carried out for identifying new treatment modalities.

Epilepsy in Angelman syndrome: A scoping review

Angelman Syndrome (AS) is characterized by severe developmental delays including marked speech impairment, movement abnormalities(ataxia, tremor), and unique behaviors such as frequent laughter and is caused by dysfunctional maternal UBE3A gene (maternal 15q11-13 deletions, maternal specific UBE3A mutation, uniparental disomy, and imprinting defect). Intractable epileptic seizures since early childhood with characteristic EEG abnormalities are present in 80-90% patients with AS. Underlying pathophysiology may involve neocortical and thalamocortical hyperexcitability secondary to severe reduction of GABAergic input, as well as dysfunctional synaptic plasticity, deficient synaptogenesis, and neuronal morphological immaturity. The onset of epilepsy is most prevalent between 1 and 3 years of age; however, approximately 25% of patients developed epilepsy before one year of age. Various types of generalized seizures are most prevalent, with most common types are myoclonic and atypical absence.More than 95% of epilepsy patients may have daily seizures at least for a limited time during early childhood, and two-third patients develop disabling seizures. Fever provoked seizures, and frequent occurrence of nonconvulsive status epilepticus are two unique features. Seizures are frequently pharmacoresistant. Considering underlying prominent GABAergic dysfunction, clinicians had used AEDs that target GABAergic signaling such as valproate, phenobarbital, and clonazepam as first-line therapies for AS. However, due to the unfavorable side effect profile of these AEDs, a recent treatment approach involves priority use of levetiracetam, clobazam, topiramate, lamotrigine, ethosuximide, VNS, and carbohydrate-restricted diets. Besides symptomatic management, there has been recent progress to find a curative treatment with the following approaches: 1. Gene/protein replacement therapy (Adeno and lentiviral vector therapy to deliver a gene or secretory protein); 2. Activation of the intact but silent paternal copy of UBE3A (antisense oligonucleotide therapy and artificial transcription factors); and 3. Downstream therapies (OV101/gaboxadol, ketone supplement, novel compounds/peptides, anti-inflammatory/regenerative therapy).

A novel intronic variant in UBE3A identified by genome sequencing in a patient with an atypical presentation of Angelman syndrome

Angelman syndrome (AS) is a genetic neurodevelopmental disorder caused by loss or deficient expression of UBE3A on the maternally inherited allele. In 10-15% of individuals with a clinical diagnosis of AS, a molecular diagnosis cannot be established with conventional testing. We describe a 13-year-old male with an atypical presentation of AS, who was found to have a novel, maternally inherited, intronic variant in UBE3A (c.3-12T>A) using genome sequencing (GS). Targeted sequencing of RNA isolated from blood confirmed the creation of a new acceptor splice site. These GS results ended a six-year diagnostic odyssey and revealed a 50% recurrence risk for the unaffected parents. This case illustrates a previously unreported splicing variant causing AS. Intronic variants identifiable by GS may account for a proportion of individuals who are suspected of having well-known genetic disorders despite negative prior genetic testing.

Characterization of sleep habits and medication outcomes for sleep disturbance in children and adults with Angelman syndrome

The objectives of this study were to characterize the sleep habits of 50 clinically referred individuals with Angelman syndrome (AS) and to retrospectively compare the effectiveness/tolerability of the three most commonly prescribed sleep medications in the sample. An experienced physician assigned a Clinical Global Impressions-Severity scale (CGI-S) score for each subject's AS-specific symptoms. Caregivers completed the Child Sleep Habits Questionnaire (CSHQ; screen for sleep problems in school-aged [4-10 years] children), a screening assessment for sleep problems. Caregivers provided information about medication trials targeting disturbed sleep, with the physician assigning a CGI-Improvement scale (CGI-I) score for each trial. Linear regression showed significant negative association between age and CSHQ score. In their lifetime, 72% of participants had taken a medication for sleep, most commonly melatonin, clonidine and trazodone. The majority continued these for 6 months or longer. With these medications, many demonstrated significant improvement in sleep disturbances, with no difference in odds of improvement between medications. Disturbed sleep was common in this cohort and significantly worse in younger-aged participants. The majority received at least one medication trial for disturbed sleep and each of the most commonly prescribed medication was effective for a substantial percentage of participants. Most participants remained on medication for at least 6 months, suggesting favorable tolerability.

Nutrition Assessment and Intervention in a Pediatric Patient with Angelman Syndrome: A Case Presentation Highlighting Clinical Challenges and Evidence-Based Solutions

BACKGROUND

Angelman syndrome (AS) is a rare disorder of genetic imprinting which results in intellectual and developmental disability. It meets criteria of a disorder of neurologic impairment. A deletion in the long arm of chromosome 15 (del 15q11.2-q13) is responsible for about 70% of cases of AS (deletion genotype).

SUMMARY

There is a paucity of evidence to allow algorithmic nutrition assessment and intervention in pediatric patients with AS. Therefore, our objective is to use a case presentation to provide an example of nutrition assessment and intervention in a pediatric patient with the deletion genotype of AS and then highlight common challenges to providing evidenced-based nutrition care. For the highlighted challenges, we suggest evidence-based solutions to provide a resource for clinicians who may encounter similar challenges in clinical practice. Key Messages: There are genotype-phenotype correlations in AS that can help guide clinicians regarding nutritionally relevant clinical characteristics and corresponding interventions that are patient specific. The deletion genotype in AS is associated with multiple characteristics that are relevant to nutrition care and may also be different and/or more severe than characteristics seen in other AS genetic mechanisms. There is also overlap in certain nutritionally relevant clinical characteristics between AS and other conditions, including Prader-Willi syndrome, autism spectrum disorders, and disorders of neurological impairment like cerebral palsy. Clinicians can utilize nutrition resources related to these conditions to expand the scope of relevant resources available.

Ocular findings and strabismus surgery outcomes in Chinese children with Angelman syndrome: Three case reports

RATIONALE

Angelman syndrome (AS) is an uncommon genetic disease characterized as serious retarded mental development and ocular abnormality.

PATIENT CONCERNS

This report aims to present the ophthalmological features, and identify the diagnosis and outcomes of strabismus surgery in AS patients.

DIAGNOSIS

Three children with exotropia were diagnosed with AS based on their typical clinical features.

INTERVENTIONS

All patients underwent multiplex ligation-dependent probe amplification (MLPA) analysis and accepted lateral rectus recession surgery with the assistance of intravenous combined inhalation anesthesia.

OUTCOMES

The maternal heritage deletion of chromosome 15q11.2-q13 was verified in all patients by MLPA. All patients with strabismus could not cooperate during the vision test, and had astigmatism. The strabismus type of AS patients was horizontal exotropia, and no vertical strabismus was found. One of these patients was combined with high myopia. The hypopigmentation on the hair and iris was ubiquitous. However, retina pigmentation was normal. After different degrees of lateral rectus recession, the exotropia was significantly relieved, and the surgical effects were stable postoperatively.

LESSONS

Horizontal exotropia is the major strabismus type. Severe intellectual disability, hyperactivity, and speech impairment are the common characteristics of AS children. Its examination and operation design remains challenging. Thus, repeated examinations and intelligence rehabilitation are essential.

An overview of health issues and development in a large clinical cohort of children with Angelman syndrome

This study presents a broad overview of health issues and psychomotor development of 100 children with Angelman syndrome (AS), seen at the ENCORE Expertise Center for AS in Rotterdam, the Netherlands. We aimed to further delineate the phenotype of AS, to evaluate the association of the phenotype with genotype and other determinants such as epilepsy and to get insight in possible targets for intervention. We confirmed the presence of a more severe phenotype in the 15q11.2‐q13 deletion subtype. Novel findings were an association of (early onset of) epilepsy with a negative effect on development, a high occurrence of nonconvulsive status epilepticus, a high rate of crouch gait in the older children with risk of deterioration of mobility, a relatively low occurrence of microcephaly, a higher mean weight for height in all genetic subtypes with a significant higher mean in the nondeletion children, and a high occurrence of hyperphagia across all genetic subtypes. Natural history data are needed to design future trials. With this large clinical cohort with structured prospective and multidisciplinary follow‐up, we provide unbiased data on AS to support further intervention studies to optimize outcome and quality of life of children with AS and their family.

A retrospective analysis of the prevalence of imprinting disorders in Estonia from 1998 to 2016

Imprinting disorders (ImpDis) represent a small group of rare congenital diseases primarily affecting growth, development, and the hormonal and metabolic systems. The aim of present study was to identify the prevalence of the ImpDis in Estonia, to describe trends in the live birth prevalence of these disorders between 1998 and 2016, and to compare the results with previously published data. We retrospectively reviewed the records of all Estonian patients since 1998 with both molecularly and clinically diagnosed ImpDis. A prospective study was also conducted, in which all patients with clinical suspicion for an ImpDis were molecularly analyzed. Eighty-seven individuals with ImpDis were identified. Twenty-seven (31%) of them had Prader-Willi syndrome (PWS), 15 (17%) had Angelman syndrome (AS), 15 (17%) had Silver-Russell syndrome (SRS), 12 (14%) had Beckwith-Wiedemann syndrome (BWS), 10 (11%) had pseudo- or pseudopseudohypoparathyroidism, four had central precocious puberty, two had Temple syndrome, one had transient neonatal diabetes mellitus, and one had myoclonus-dystonia syndrome. One third of SRS and BWS cases fulfilled the diagnostic criteria for these disorders, but tested negative for genetic abnormalities. Seventy-six individuals were alive as of January 1, 2018, indicating the total prevalence of ImpDis in Estonia is 5.8/100,000 (95% CI 4.6/100,000-7.2/100,000). The minimum live birth prevalence of all ImpDis in Estonia in 2004-2016 was 1/3,462, PWS 1/13,599, AS 1/27,198, BWS 1/21,154, SRS 1/15,866, and PHP/PPHP 1/27,198. Our results are only partially consistent with previously published data. The worldwide prevalence of SRS and GNAS-gene-related ImpDis is likely underestimated and may be at least three times higher than expected.

Genetic testing for Prader-Willi syndrome and Angelman syndrome in the clinical practice of Guangdong Province, China

Background

Prader-Willi syndrome (PWS) and Angelman syndrome (AS) are clinically distinct neurodevelopmental disorders caused by absence of paternally or maternally expressed imprinted genes on chromosome 15q11.2-q13.3 region.

Methods

3331 individuals was recruited from June 2013 to December 2016 under an institutional review board-approved protocol of informed consent. The methylation-specific PCR was employed as a first-tier screening test. The multiplex-fluorescent-labeled STR linkage analysis was carried out to define the underlying genetic mechanisms. The chromosomal microarray analysis was employed to identify chromosomal breakpoints in confirmed cases, and to detect other chromosomal abnormalities in undiagnosed cases. Genetic counseling and recurrence risk assessment were provided to families with affected individuals.

Results

The methylation-specific PCR identified 36 PWS suspected patients and 13 AS suspected patients. UBE3A sequence analysis identified another 1 patient with AS. The STR linkage analysis define the underlying genetic mechanisms. Thirty PWS patients were with paternal deletions on chromosome region 15q11-q13, 5 with isodisomic uniparental disomy and 1 with mixed segmental isodisomic/ heterodisomic uniparental disomy of maternal chromosome 15. Twelve AS patients were with maternal deletions, 1 with isodisomic uniparental disomy and 1 with UBE3A gene mutation. The chromosomal microarray analysis identified chromosomal breakpoints in confirmed cases, and detected chromosomal abnormalities in another 4 patients with clinically overlapped features but tested negative for PWS/AS. Genetic counseling was offered to all families with affected individuals.

Conclusions

Identifying the disorders at early age, establishing the molecular mechanisms, carrying out treatment intervention and close monitoring can significantly improve the prognosis of PWS/AS patients.

Atypical Angelman syndrome due to a mosaic imprinting defect: Case reports and review of the literature

Angelman syndrome (AS) is characterized by severe intellectual disability, limited, or absent speech and a generally happy demeanor. The four known etiological mechanisms; deletions, uniparental disomy, imprinting defects, and UBE3A mutation all affect expression of the UBE3A gene at 15q11-q13. An atypical phenotype is seen in individuals who are mosaic for a chromosome 15q11-q13 imprinting defect on the maternal allele. These patients present with a milder phenotype, often with hyperphagia and obesity or non-specific intellectual disability. Unlike typical AS syndrome, they can have a vocabulary up to 100 words and speak in sentences. Ataxia and seizures may not be present, and the majority of individuals do not have microcephaly. Here we review the current literature and present three individuals with atypical AS caused by a mosaic imprinting defect to demonstrate why DNA methylation analysis at the SNRPN locus needs to be considered in a broader clinical context. © 2017 Wiley Periodicals, Inc.

Angelman syndrome: Current and emerging therapies in 2016

Angelman syndrome (AS) is a severe neurodevelopmental disorder caused by a loss of the maternally-inherited UBE3A; the paternal UBE3A is silenced in neurons by a mechanism involving an antisense transcript (UBE3A-AS) at the unmethylated paternal locus. We reviewed all published information on the clinical trials that have been completed as well as the publicly available information on ongoing trials of therapies in AS. To date, all clinical trials that strove to improve neurodevelopment in AS have been unsuccessful. Attempts at hypermethylating the maternal locus through dietary compounds were ineffective. The results of an 8-week open-label trial using minocycline as a matrix metalloproteinase-9 inhibitor were inconclusive, while a subsequent randomized placebo-controlled trial suggested that treatment with minocycline for 8 weeks did not result in any neurodevelopmental gains. A 1-year randomized placebo-controlled trial using levodopa to alter the phosphorylation of calcium/calmodulin-dependent kinase II did not lead to any improvement in neurodevelopment. Topoisomerase inhibitors and antisense oligonucleotides are being developed to directly inhibit UBE3A-AS. Artificial transcription factors are being developed to "super activate" UBE3A or inhibit UBE3A-AS. Other strategies targeting specific pathways are briefly discussed. We also reviewed the medications that are currently used to treat seizures and sleep disturbances, which are two of the more common complications of AS. © 2016 Wiley Periodicals, Inc.