Angelman syndrome: Mutations influence features in early childhood

Community-Sourced Reporting of Mortalities in Angelman Syndrome (1979-2022)

Angelman syndrome (AS) is a severe genetic neurodevelopmental disorder with an estimated prevalence of 1:20,000. Life expectancy appears to be normal, however, data regarding lifespan in AS are scarce. Until 2018, there was no unique diagnosis code for AS, thus true incidence, prevalence, mortality and morbidity rates are unknown. A social media effort was launched by caregivers of people with AS to gather community-sourced data to understand AS mortality risks. Information on 220 deaths was verified with obituaries and public postings. Respiratory illness was the primary cause of death among people with AS overall, followed by accidents and seizures. Surprisingly, sudden unexpected death in sleep (SUDS) was the fourth most common cause, which has not been reported previously. Approximately 91% of people with AS have epilepsy, thus some SUDS cases may represent sudden unexpected deaths in epilepsy (SUDEP). Causes of death vary by age, and differ from the general population. Though there are obvious limitations to data collected through social media, grass roots science is a starting point to amass preliminary data and inform future epidemiological research on AS.

Clinical and Cytogenetic Impact of Maternal Balanced Double Translocation: A Familial Case of 15q11.2 Microduplication and Microdeletion Syndromes with Genetic Counselling Implications

BACKGROUND

Balanced chromosomal translocations occur in approximately 0.16 to 0.20% of live births. While most carriers are phenotypically normal, they are at risk of generating unbalanced gametes during meiosis, leading to genetic anomalies such as aneuploidies, deletions, duplications, and gene disruptions. These anomalies can result in spontaneous abortions or congenital anomalies, including neurodevelopmental disorders. Complex chromosomal rearrangements (CCRs) involving more than two chromosomes are rare but further increase the probability of producing unbalanced gametes. Neurodevelopmental disorders such as Angelman syndrome (AS) and duplication 15q11q13 syndrome (Dup15q) are associated with such chromosomal abnormalities.

METHODS

This study describes a family with a de novo maternal balanced double translocation involving chromosomes 13, 19, and 15, resulting in two offspring with unbalanced chromosomal abnormalities. Cytogenetic evaluations were performed using GTG banding, fluorescence in situ hybridization (FISH), and low-pass whole-genome sequencing (LP-WGS). Methylation analysis was conducted using methylation-sensitive high-resolution melting (MS-HRM) to diagnose Angelman syndrome.

RESULTS

The cytogenetic and molecular analyses identified an 8.9 Mb duplication in 15q11.2q13.3 in one child, and an 8.9 Mb deletion in the same region in the second child. Both abnormalities affected critical neurodevelopmental genes, such as SNRPN. FISH and MS-HRM confirmed the chromosomal imbalances and the diagnosis of Angelman syndrome in the second child. The maternal balanced translocation was found to be cryptic, contributing to the complex inheritance pattern.

CONCLUSION

This case highlights the importance of using multiple genetic platforms to uncover complex chromosomal rearrangements and their impact on neurodevelopmental disorders. The findings underscore the need for thorough genetic counseling, especially in families with such rare chromosomal alterations, to manage reproductive outcomes and neurodevelopmental risks.

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.

A clinical-translational review of sleep problems in neurodevelopmental disabilities

Sleep disorders are very common across neurodevelopmental disorders and place a large burden on affected children, adolescents, and their families. Sleep disturbances seem to involve a complex interplay of genetic, neurobiological, and medical/environmental factors in neurodevelopmental disorders. In this review, we discuss animal models of sleep problems and characterize their presence in two single gene disorders, Rett Syndrome, and Angelman Syndrome and two more commonly occurring neurodevelopmental disorders, Down Syndrome, and autism spectrum disorders. We then discuss strategies for novel methods of assessment using wearable sensors more broadly for neurodevelopmental disorders in general, including the importance of analytical validation. An increased understanding of the mechanistic contributions and potential biomarkers of disordered sleep may offer quantifiable targets for interventions that improve overall quality of life for affected individuals and their families.

Autism and Epilepsy

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

Outcome measures in Angelman syndrome

BACKGROUND

Angelman syndrome (AS) is a rare neurodevelopmental disorder characterized by severe intellectual disability, little to no expressive speech, visual and motor problems, emotional/behavioral challenges, and a tendency towards hyperphagia and weight gain. The characteristics of AS make it difficult to measure these children's functioning with standard clinical tests. Feasible outcome measures are needed to measure current functioning and change over time, in clinical practice and clinical trials.

AIM

Our first aim is to assess the feasibility of several functional tests. We target domains of neurocognitive functioning and physical growth using the following measurement methods: eye-tracking, functional Near-Infrared Spectroscopy (fNIRS), indirect calorimetry, bio-impedance analysis (BIA), and BOD POD (air-displacement plethysmography). Our second aim is to explore the results of the above measures, in order to better understand the AS phenotype.

METHODS

The study sample consisted of 28 children with AS aged 2-18 years. We defined an outcome measure as feasible when (1) at least 70% of participants successfully finished the measurement and (2) at least 60% of those participants had acceptable data quality. Adaptations to the test procedure and reasons for early termination were noted. Parents rated acceptability and importance and were invited to make recommendations to increase feasibility. The results of the measures were explored.

RESULTS

Outcome measures obtained with eye-tracking and BOD POD met the definition of feasibility, while fNIRS, indirect calorimetry, and BIA did not. The most important reasons for early termination of measurements were showing signs of protest, inability to sit still and poor/no calibration (eye-tracking specific). Post-calibration was often applied to obtain valid eye-tracking results. Parents rated the BOD POD als most acceptable and fNIRS as least acceptable for their child. All outcome measures were rated to be important. Exploratory results indicated longer reaction times to high salient visual stimuli (eye-tracking) as well as high body fat percentage (BOD POD).

CONCLUSIONS

Eye-tracking and BOD POD are feasible measurement methods for children with AS. Eye-tracking was successfully used to assess visual orienting functions in the current study and (with some practical adaptations) can potentially be used to assess other outcomes as well. BOD POD was successfully used to examine body composition.

TRIAL REGISTRATION

Registered d.d. 23-04-2020 under number 'NL8550' in the Dutch Trial Register: https://onderzoekmetmensen.nl/en/trial/23075.

DLG3 variants caused X-linked epilepsy with/without neurodevelopmental disorders and the genotype-phenotype correlation

Background

The DLG3 gene encodes disks large membrane-associated guanylate kinase scaffold protein 3, which plays essential roles in the clustering of N-methyl-D-aspartate receptors (NMDARs) at excitatory synapses. Previously, DLG3 has been identified as the causative gene of X-linked intellectual developmental disorder-90 (XLID-90; OMIM# 300850). This study aims to explore the phenotypic spectrum of DLG3 and the genotype-phenotype correlation.

Methods

Trios-based whole-exome sequencing was performed in patients with epilepsy of unknown causes. To analyze the genotype-phenotype correlations, previously reported DLG3 variants were systematically reviewed.

Results

DLG3 variants were identified in seven unrelated cases with epilepsy. These variants had no hemizygous frequencies in controls. All variants were predicted to be damaging by silico tools and alter the hydrogen bonds with surrounding residues and/or protein stability. Four cases mainly presented with generalized seizures, including generalized tonic-clonic and myoclonic seizures, and the other three cases exhibited secondary generalized tonic-clonic seizures and focal seizures. Multifocal discharges were recorded in all cases during electroencephalography monitoring, including the four cases with generalized discharges initially but multifocal discharges after drug treating. Protein-protein interaction network analysis revealed that DLG3 interacts with 52 genes with high confidence, in which the majority of disease-causing genes were associated with a wide spectrum of neurodevelopmental disorder (NDD) and epilepsy. Three patients with variants locating outside functional domains all achieved seizure-free, while the four patients with variants locating in functional domains presented poor control of seizures. Analysis of previously reported cases revealed that patients with non-null variants presented higher percentages of epilepsy than those with null variants, suggesting a genotype-phenotype correlation.

Significance

This study suggested that DLG3 variants were associated with epilepsy with/without NDD, expanding the phenotypic spectrum of DLG3. The observed genotype-phenotype correlation potentially contributes to the understanding of the underlying mechanisms driving phenotypic variation.

Bone health in children with Angelman syndrome at the ENCORE Expertise Center

Angelman syndrome (AS) is a rare genetic disorder due to lack of UBE3A function on chromosome 15q11.2q13 caused by a deletion, uniparental paternal disomy (UPD), imprinting center disorder (ICD), or pathological variant of the UBE3A gene. AS is characterized by developmental delay, epilepsy, and lack of speech. Although fractures are observed frequently in our clinical practice, there are few studies on bone health in AS. The aim of this study is to investigate bone health in children with AS. In this prospective cohort study, we describe bone health in 91 children with AS visiting the ENCORE Expertise Center for AS between April 2010 and December 2021. Bone health was assessed with the bone health index (BHI) in standard deviation score (SDS) measured by digital radiogrammetry of the left hand using BoneXpert software. Risk factors analyzed were age, sex, genetic subtype, epilepsy, anti-seizure medication use, mobility, body mass index (BMI), and onset of puberty. Children with AS had a mean BHI of -1.77 SDS (SD 1.4). A significantly lower BHI was found in children with a deletion (-2.24 SDS) versus non-deletion (-1.02 SDS). Other factors associated with reduced BHI-SDS were inability to walk and late onset of puberty. Children with a history of one or more fractures (22%) had a significantly lower BHI than children without fractures (-2.60 vs -1.56 SDS). Longitudinal analysis showed a significant decrease in BHI-SDS with age in all genetic subtypes.  Conclusions: Children with AS have a reduced bone health. Risk factors are deletion genotype, no independent walking, and late onset of puberty. Bone health decreased significantly with age. What is Known: • Children with neurological disorders often have a low bone health and higher risk of fractures. • Little is known about bone health in children with Angelman syndrome (AS). What is New: • Children with AS showed a reduced bone health and this was significantly associated with having a deletion, not being able to walk independently, and late onset of puberty. • Longitudinal analysis showed a significant decrease in bone health as children got older.

Age of diagnosis for children with chromosome 15q syndromes

OBJECTIVE

The objective of this study was to identify the age of diagnosis for children with one of three neurogenetic conditions resulting from changes in chromosome 15 (Angelman syndrome [AS], Prader-Willi syndrome [PWS], and duplication 15q syndrome [Dup15q]).

METHODS

Data about the diagnostic process for each condition were contributed by the advocacy organizations. Median and interquartile ranges were calculated for each condition by molecular subtype and year. Comparison tests were run to explore group differences.

RESULTS

The median age of diagnosis was 1.8 years for both AS and Dup15q. PWS was diagnosed significantly younger at a median age of 1 month. Deletion subtypes for both PWS and AS were diagnosed earlier than nondeletion subtypes, and children with isodicentric duplications in Dup15q were diagnosed earlier than those with interstitial duplications.

CONCLUSION

Understanding variability in the age of diagnosis for chromosome 15 disorders is an important step in reducing the diagnostic odyssey and improving access to interventions for these populations. Results from this study provide a baseline by which to evaluate efforts to reduce the age of diagnosis for individuals with these conditions.

Short Stature and Distinct Growth Characteristics in Angelman Syndrome

INTRODUCTION

Angelman syndrome (AS) is a rare, genetic, neurodevelopmental disorder characterized by severe impairments in speech, cognition, and motor skills accompanied by unique behaviors, distinct facial features, and high prevalence of epilepsy and sleep problems. Despite some reports of short stature among AS patients, this feature is not included in the clinical criteria defined in 2005. We investigated growth patterns among AS patients with respect to mutation type, growth periods, family history, and endocrine abnormalities.

METHODS

Data were collected from patients' medical files in AS National Clinic. Mutation subtypes were divided to deletion and non-deletion. Four growth periods were defined: preschool, childhood, peak height velocity, and final height.

RESULTS

The cohort included 88 individuals (46 males), with 54 (61.4%) carrying deletion subtype. A median of 3 observations per individual produced 280 data points. Final height SDS was significantly lower compared to general population (-1.23 ± 1.26, p < 0.001), and in deletion group versus non-deletion (-1.67 ± 1.3 vs. -0.65 ± 0.96, p = 0.03). Final height SDS was significantly lower compared to height SDS in preschool period (-1.32 vs. -0.47, p = 0.007). Patient's final height SDS was significantly lower than the parents' (∆final-height SDS = 0.94 ± 0.99, p = 0.002). IGF1-SDS was significantly decreased compared to general population (-0.55 ± 1.61, p = 0.04), with lower values among deletion group (-0.70 ± 1.44, p = 0.01).

CONCLUSIONS

AS patients demonstrate specific growth pattern with deceleration during childhood and adolescence, resulting in significantly decreased final height compared to normal population, and even lower among deletion subgroup, which could be attributed to reduced IGF1 levels. We propose adding short stature to the clinical criteria and developing adjusted growth curves for AS population.

Hyperphagia, Growth, and Puberty in Children with Angelman Syndrome

Angelman Syndrome (AS) is a rare genetic disorder caused by lack of maternal UBE3A protein due to a deletion of the chromosome 15q11.2-q13 region, uniparental paternal disomy, imprinting center defect, or pathogenic variant in the UBE3A gene. Characteristics are developmental delay, epilepsy, behavioral, and sleep problems. There is some evidence for hyperphagia, shorter stature, and higher BMI compared to neurotypical children, but longitudinal studies on growth are lacking. In this study, we analyzed prospectively collected data of 145 children with AS, who visited the ENCORE Expertise Center between 2010 and 2021, with a total of 853 visits. Children showed an elevated mean score of 25 on the Dykens Hyperphagia questionnaire (range 11-55) without genotype association. Higher scores were significantly associated with higher body mass index (BMI) standard deviation scores (SDS) (p = 0.004). Mean height was -1.2 SDS (SD 1.3), mean BMI-SDS was 0.6 (SD 1.7); 43% had a BMI-SDS > 1 and 20% had a BMI-SDS > 2. Higher BMI-SDS was significantly associated with non-deletion genotype (p = 0.037) and walking independently (p = 0.023). Height SDS decreased significantly with age (p < 0.001) and BMI-SDS increased significantly with age (p < 0.001. Onset of puberty was normal. In conclusion, children with AS showed moderate hyperphagia, lower height SDS, and higher BMI-SDS compared to norm data, with increasing deviation from the norm with age. It is uncertain how loss of maternal UBE3A function may influence growth. Attention to diet, exercise, and hyperphagia from an early age is recommended to prevent obesity and associated health problems.

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.

Systematic Review: Emotion Dysregulation in Syndromic Causes of Intellectual and Developmental Disabilities

OBJECTIVE

To summarize the current state of the literature regarding emotion dysregulation (ED) in syndromic intellectual disabilities (S-IDs) in 6 of the most common forms of S-IDs-Down syndrome, fragile X syndrome (FXS), tuberous sclerosis complex, Williams syndrome, Prader-Willi syndrome, and Angelman syndrome-and to determine future research directions for identification and treatment of ED.

METHOD

PubMed bibliographic database was searched from date of inception to May 2021. PRISMA 2020 guidelines were followed with the flowchart, table of included studies, list of excluded studies, and checklist provided. Filters applied included human research and English. Only original research articles were included in the final set, but review articles were used to identify secondary citations of primary studies. All articles were reviewed for appropriateness by 2 authors and summarized. Inclusion criteria were met by 145 articles (Down syndrome = 29, FXS = 55, tuberous sclerosis complex = 11, Williams syndrome = 18, Prader-Willi syndrome = 24, Angelman syndrome = 8).

RESULTS

Each syndrome review was summarized separately and further subdivided into articles related to underlying neurobiology, behaviors associated with ED, assessment, and targeted intervention. FXS had the most thorough research base, followed by Down syndrome and Prader-Willi syndrome, with the other syndromes having more limited available research. Very limited research was available regarding intervention for all disorders except FXS.

CONCLUSION

Core underlying characteristics of S-IDs appear to place youth at higher risk for ED, but further research is needed to better assess and treat ED in S-IDs. Future studies should have a standard assessment measure of ED, such as the Emotion Dysregulation Inventory, and explore adapting established curricula for ED from the neurotypical and autism spectrum disorder fields.

Linoleic acid improves PIEZO2 dysfunction in a mouse model of Angelman Syndrome

Angelman syndrome (AS) is a neurogenetic disorder characterized by intellectual disability and atypical behaviors. AS results from loss of expression of the E3 ubiquitin-protein ligase UBE3A from the maternal allele in neurons. Individuals with AS display impaired coordination, poor balance, and gait ataxia. PIEZO2 is a mechanosensitive ion channel essential for coordination and balance. Here, we report that PIEZO2 activity is reduced in Ube3a deficient male and female mouse sensory neurons, a human Merkel cell carcinoma cell line and female human iPSC-derived sensory neurons with UBE3A knock-down, and de-identified stem cell-derived neurons from individuals with AS. We find that loss of UBE3A decreases actin filaments and reduces PIEZO2 expression and function. A linoleic acid (LA)-enriched diet increases PIEZO2 activity, mechano-excitability, and improves gait in male AS mice. Finally, LA supplementation increases PIEZO2 function in stem cell-derived neurons from individuals with AS. We propose a mechanism whereby loss of UBE3A expression reduces PIEZO2 function and identified a fatty acid that enhances channel activity and ameliorates AS-associated mechano-sensory deficits.

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.

Angelman syndrome with mosaic paternal uniparental disomy suggestive of mitotic nondisjunction

Angelman syndrome (AS) is caused by the functional absence of the maternal ubiquitin-protein ligase E3A (UBE3A) gene. Approximately 5% of AS is caused by paternal uniparental disomy of chromosome 15 (UPD(15)pat), most of which is considered to result from monosomy rescue. However, little attention has focused on how UPD(15)pat occurs. We suggest the mitotic nondisjunction mechanism as a cause of UPD(15)pat in a six-year-old patient presenting with distinctive characteristics in line with AS. DNA methylation screening of 15q11-q13 showed a paternal band and a faint maternal band, suggestive of mosaic status. By trio-based microsatellite analysis, we confirmed a large proportion of UPD(15)pat cells and a small proportion of cells of biparental origin. Single nucleotide polymorphism (SNP) microarray revealed isodisomy of the entire chromosome 15. These results suggest that the UPD(15)pat of the patient resulted from mitotic nondisjunction, which may also be the cause of other cases of AS with UPD(15)pat.

Association between early and current gastro-intestinal symptoms and co-morbidities in children and adolescents with Angelman syndrome

BACKGROUND

Angelman syndrome (AS) is a neurogenetic disorder that causes severe intellectual disability, expressive language deficits, motor impairment, ataxia, sleep problems, epileptic seizures and a happy disposition. People with AS frequently experience gastrointestinal (GI) symptoms.

METHOD

This study used data from the Global Angelman Syndrome Registry to explore the relationship between early and current GI symptoms and co-morbidity in children and adolescents with AS (n = 173). Two groups that experienced a high (n = 91) and a low (n = 82) frequency of GI symptoms were examined in relation to feeding and GI history in infancy, sleep and toileting problems, levels of language and communication and challenging behaviours. Predictors of GI symptoms were then investigated using a series of logistic regressions.

RESULTS

This analysis found that constipation and gastroesophageal reflux affected 84% and 64%, of the sample, respectively. The high frequency of GI symptoms were significantly associated with: 'refusal to nurse', 'vomiting', 'arching', 'difficulty gaining weight', gastroesophageal reflux, 'solid food transition', frequency of night-time urinary continence and sleep hyperhidrosis during infancy. GI symptoms were not significantly associated with sleep, toileting, language or challenging behaviours. Significant predictors of high frequency GI symptoms were gastroesophageal reflux and sleep hyperhidrosis.

CONCLUSIONS

Future research needs to investigate the association between AS and GI co-morbidity in adults with AS.

Dissociating motor impairment from five-choice serial reaction time task performance in a mouse model of Angelman syndrome

Angelman syndrome (AS) is a single-gene neurodevelopmental disorder associated with cognitive and motor impairment, seizures, lack of speech, and disrupted sleep. AS is caused by loss-of-function mutations in the UBE3A gene, and approaches to reinstate functional UBE3A are currently in clinical trials in children. Behavioral testing in a mouse model of AS (Ube3a m-/p+ ) represents an important tool to assess the effectiveness of current and future treatments preclinically. Existing behavioral tests effectively model motor impairments, but not cognitive impairments, in Ube3a m-/p+ mice. Here we tested the hypothesis that the 5-choice serial reaction time task (5CSRTT) can be used to assess cognitive behaviors in Ube3a m-/p+ mice. Ube3a m-/p+ mice had more omissions during 5CSRTT training than wild-type littermate controls, but also showed impaired motor function including open field hypoactivity and delays in eating pellet rewards. Motor impairments thus presented an important confound for interpreting this group difference in omissions. We report that despite hypoactivity during habituation, Ube3a m-/p+ mice had normal response latencies to retrieve rewards during 5CSRTT training. We also accounted for delays in eating pellet rewards by assessing omissions solely on trials where eating delays would not impact results. Thus, the increase in omissions in Ube3a m-/p+ mice is likely not caused by concurrent motor impairments. This work underscores the importance of considering how known motor impairments in Ube3a m-/p+ mice may affect behavioral performance in other domains. Our results also provide guidance on how to design a 5CSRTT protocol that is best suited for future studies in Ube3a mutants.

Touchscreen Cognitive Deficits, Hyperexcitability, and Hyperactivity in Males and Females Using Two Models of Cdkl5 Deficiency

Many neurodevelopmental disorders (NDDs) are the result of mutations on the X chromosome. One severe NDD resulting from mutations on the X chromosome is CDKL5 deficiency disorder (CDD). CDD is an epigenetic, X-linked NDD characterized by intellectual disability (ID), pervasive seizures and severe sleep disruption, including recurring hospitalizations. CDD occurs at a 4:1 ratio, with a female bias. CDD is driven by the loss of cyclin-dependent kinase-like 5 (CDKL5), a serine/threonine kinase that is essential for typical brain development, synapse formation and signal transmission. Previous studies focused on male subjects from animal models, likely to avoid the complexity of X mosaicism. For the first time, we report translationally relevant behavioral phenotypes in young adult (8–20 weeks) females and males with robust signal size, including impairments in learning and memory, substantial hyperactivity and increased susceptibility to seizures/reduced seizure thresholds, in both sexes, and in two models of CDD preclinical mice, one with a general loss-of-function mutation and one that is a patient-derived mutation.

Gait as a quantitative translational outcome measure in Angelman syndrome

Angelman syndrome (AS) is a genetic neurodevelopmental disorder characterized by developmental delay, lack of speech, seizures, intellectual disability, hypotonia, and motor coordination deficits. Motor abilities are an important outcome measure in AS as they comprise a broad repertoire of metrics including ataxia, hypotonia, delayed ambulation, crouched gait, and poor posture, and motor dysfunction affects nearly every individual with AS. Guided by collaborative work with AS clinicians studying gait, the goal of this study was to perform an in‐depth gait analysis using the automated treadmill assay, DigiGait. Our hypothesis is that gait presents a strong opportunity for a reliable, quantitative, and translational metric that can serve to evaluate novel pharmacological, dietary, and genetic therapies. In this study, we used an automated gait analysis system, in addition to standard motor behavioral assays, to evaluate components of motor, exploration, coordination, balance, and gait impairments across the lifespan in an AS mouse model. Our study demonstrated marked global motoric deficits in AS mice, corroborating previous reports. Uniquely, this is the first report of nuanced aberrations in quantitative spatial and temporal components of gait in AS mice compared to sex‐ and age‐matched wildtype littermates followed longitudinally using metrics that are analogous in AS individuals. Our findings contribute evidence toward the use of nuanced motor outcomes (i.e., gait) as valuable and translationally powerful metrics for therapeutic development for AS, as well as other genetic neurodevelopmental syndromes.

A multidisciplinary approach and consensus statement to establish standards of care for Angelman syndrome

BACKGROUND

Angelman syndrome (AS) is a rare neurogenetic disorder present in approximately 1/12,000 individuals and characterized by developmental delay, cognitive impairment, motor dysfunction, seizures, gastrointestinal concerns, and abnormal electroencephalographic background. AS is caused by absent expression of the paternally imprinted gene UBE3A in the central nervous system. Disparities in the management of AS are a major problem in preparing for precision therapies and occur even in patients with access to experts and recognized clinics. AS patients receive care based on collective provider experience due to limited evidence-based literature. We present a consensus statement and comprehensive literature review that proposes a standard of care practices for the management of AS at a critical time when therapeutics to alter the natural history of the disease are on the horizon.

METHODS

We compiled the key recognized clinical features of AS based on consensus from a team of specialists managing patients with AS. Working groups were established to address each focus area with committees comprised of providers who manage >5 individuals. Committees developed management guidelines for their area of expertise. These were compiled into a final document to provide a framework for standardizing management. Evidence from the medical literature was also comprehensively reviewed.

RESULTS

Areas covered by working groups in the consensus document include genetics, developmental medicine, psychology, general health concerns, neurology (including movement disorders), sleep, psychiatry, orthopedics, ophthalmology, communication, early intervention and therapies, and caregiver health. Working groups created frameworks, including flowcharts and tables, to help with quick access for providers. Data from the literature were incorporated to ensure providers had review of experiential versus evidence-based care guidelines.

CONCLUSION

Standards of care in the management of AS are keys to ensure optimal care at a critical time when new disease-modifying therapies are emerging. This document is a framework for providers of all familiarity levels.

An in vivo Cell-Based Delivery Platform for Zinc Finger Artificial Transcription Factors in Pre-clinical Animal Models

Zinc finger (ZF), transcription activator-like effectors (TALE), and CRISPR/Cas9 therapies to regulate gene expression are becoming viable strategies to treat genetic disorders, although effective in vivo delivery systems for these proteins remain a major translational hurdle. We describe the use of a mesenchymal stem/stromal cell (MSC)-based delivery system for the secretion of a ZF protein (ZF-MSC) in transgenic mouse models and young rhesus monkeys. Secreted ZF protein from mouse ZF-MSC was detectable within the hippocampus 1 week following intracranial or cisterna magna (CM) injection. Secreted ZF activated the imprinted paternal Ube3a in a transgenic reporter mouse and ameliorated motor deficits in a Ube3a deletion Angelman Syndrome (AS) mouse. Intrathecally administered autologous rhesus MSCs were well-tolerated for 3 weeks following administration and secreted ZF protein was detectable within the cerebrospinal fluid (CSF), midbrain, and spinal cord. This approach is less invasive when compared to direct intracranial injection which requires a surgical procedure.

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.

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.

The Angelman Syndrome Online Registry - A multilingual approach to support global research

In collaboration with the German Angelman syndrome (AS) community, we developed a web-based AS Online Registry to congregate existing as well as future information and scientifically quantify observations made by parents, families and medical professionals. With its user-friendly design as well as its concise and multilingual questionnaire, the registry aims at families who had so far refrained from being recruited by other, more comprehensive and/or English-only, registries. Data can be entered by both parents/families and medical professionals. The study design allows for re-contacting individuals (e.g. to request additional information) enabling collection of longitudinal data. Since its launch in June 2020, more than 200 individuals with AS age 2 month to 83 years have registered and entered their clinical and genetic data. In addition to the German, Turkish, English, Dutch, Italian, Danish and Finnish versions of the registry, we aim for translation into further languages to enable international and user-friendly recruitment of AS individuals. This novel registry will allow for extensive genotype-phenotype correlations and facilitate sharing of de-identified information among clinicians, researchers as well as the Global AS Registry. Furthermore, the registry will allow for identification of individuals suitable for future clinical or pharmacologic trials according to particular genotypic and/or phenotypic properties.

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.

Delta power robustly predicts cognitive function in Angelman syndrome

Objective

Angelman syndrome (AS) is a severe neurodevelopmental disorder caused by loss of function of the maternally inherited UBE3A gene in neurons. Promising disease‐modifying treatments to reinstate UBE3A expression are under development and an early measure of treatment response is critical to their deployment in clinical trials. Increased delta power in EEG recordings, reflecting abnormal neuronal synchrony, occurs in AS across species and correlates with genotype. Whether delta power provides a reliable biomarker for clinical symptoms remains unknown.

Methods

We analyzed combined EEG recordings and developmental assessments in a large cohort of individuals with AS (N = 82 subjects, 133 combined EEG and cognitive assessments, 1.08–28.16 years; 32F) and evaluated delta power as a biomarker for cognitive function, as measured by the Bayley Cognitive Score. We examined the robustness of this biomarker to varying states of consciousness, recording techniques and analysis procedures.

Results

Delta power predicted the Bayley Scale cognitive score (P < 10⁻⁵, R² = 0.9374) after controlling for age (P < 10⁻²⁴), genotype:age (P < 10⁻¹¹), and repeat assessments (P < 10⁻⁸), with the excellent fit on cross validation (R² = 0.95). There were no differences in model performance across states of consciousness or bipolar versus average montages (ΔAIC < 2). Models using raw data excluding frontal channels outperformed other models (ΔAIC > 4) and predicted performance in expressive (P = 0.0209) and receptive communication (P < 10⁻³) and fine motor skills (P < 10⁻⁴).

Interpretation

Delta power is a simple, direct measure of neuronal activity that reliably correlates with cognitive function in AS. This electrophysiological biomarker offers an objective, clinically relevant endpoint for treatment response in emerging clinical trials.

Epilepsy-Associated UBE3A Deficiency Downregulates Retinoic Acid Signalling Pathway

Ubiquitin-protein ligase E3A (UBE3A) has dual functions as a E3 ubiquitin-protein ligase and coactivator of nuclear hormone receptors. Mutations or deletions of the maternally inherited UBE3A gene cause Angelman syndrome. Here, we performed transcriptome profiling in the hippocampus of Ube3a^m+/p+ and Ube3a^m–/p+ mice, and determined that the expression of the retinoic acid (RA) signalling pathway was downregulated in Ube3a-deficient mice compared to WT mice. Furthermore, we demonstrated that UBE3A directly interacts with RARα and may function as a coactivator of the nuclear receptor RARα to participate in the regulation of gene expression. Loss of UBE3A expression caused the downregulation of the expression of RA-related genes, including Erbb4, Dpysl3, Calb1, Pten, and Arhgap5 in Ube3a^m–/p+ mice brain tissues. This work revealed a new role for UBE3A in regulating retinoic acid (RA) signalling downstream genes and hopefully to shed light on the potential drug target of AS.

Development of an adapted Clinical Global Impression scale for use in Angelman syndrome

BACKGROUND

The Clinical Global Impression-Severity (CGI-S) and CGI-Improvement (CGI-I) scales are widely accepted tools that measure overall disease severity and change, synthesizing the clinician's impression of the global state of an individual. Frequently employed in clinical trials for neuropsychiatric disorders, the CGI scales are typically used in conjunction with disease-specific rating scales. When no disease-specific rating scale is available, the CGI scales can be adapted to reflect the specific symptom domains that are relevant to the disorder. Angelman syndrome (AS) is a rare, clinically heterogeneous condition for which there is no disease-specific rating scale. This paper describes efforts to develop standardized, adapted CGI scales specific to AS for use in clinical trials.

METHODS

In order to develop adapted CGI scales specific to AS, we (1) reviewed literature and interviewed caregivers and clinicians to determine the most impactful symptoms, (2) engaged expert panels to define and operationalize the symptom domains identified, (3) developed detailed rating anchors for each domain and for global severity and improvement ratings, (4) reviewed the anchors with expert clinicians and established minimally clinically meaningful change for each symptom domain, and (5) generated mock patient vignettes to test the reliability of the resulting scales and to standardize rater training. This systematic approach to developing, validating, and training raters on a standardized, adapted CGI scale specifically for AS is described herein.

RESULTS

The resulting CGI-S/I-AS scales capture six critical domains (behavior, gross and fine motor function, expressive and receptive communication, and sleep) defined by caregivers and expert clinicians as the most challenging for patients with AS and their families.

CONCLUSIONS

Rigorous training and careful calibration for clinicians will allow the CGI-S/-I-AS scales to be reliable in the context of randomized controlled trials. The CGI-S/-I-AS scales are being utilized in a Phase 3 trial of gaboxadol for the treatment of AS.

Clinical aspects of a large group of adults with Angelman syndrome

Descriptions of the clinical features of Angelman syndrome (AS) have mainly been focused on children. Here, we describe the evolution of the clinical phenotypes of AS in adulthood, using clinical data from 95 individuals (mean age 31.6 years, median 29.0 years, range 18-83 years), with genetically confirmed AS. Data was collected through physical examination and inspection of medical records, combined with questionnaires and interviews. Adults with AS experience substantial debilitating health problems. Constipation, reflux, visual problems, scoliosis, behavioral and sleeping problems occurred frequently and require appropriate attention. Epilepsy was reported in 57% of adults, negatively affecting the level of functioning. Non-convulsive status epilepticus was not observed in the adults, however some individuals developed prolonged episodes of rhythmic shaking while awake. A decline in mobility was noted in the majority of adults. A minority of adults with AS showed microcephaly. Taken together, this first phenotypic study of adults with AS to include in person interviews with care-givers and physical examination of patients, including the eldest adult reported to date, provides important insight in the development of the syndrome into adulthood. This knowledge is required to improve care for adult individuals with AS and to evaluate future therapies for this group.

The effect of Angelman syndrome on enamel and dentin mineralization

AIMS

To analyze the mineralization and ion content in deciduous, permanent teeth of Angelman syndrome in comparison to match-paired teeth from normal children.

METHODS

Three deciduous teeth and a third molar and a mesiodens extracted during routine dental treatment and their match-paired normal teeth were examined using energy dispersive X-ray spectrometer program under a scanning electron microscope.

RESULTS

The morphology of the enamel and dentin of Angelman syndrome (AS) teeth was similar to normal but the thickness of the enamel of deciduous canine and permanent teeth was reduced. The most marked differences were found in the enamel-in AS teeth, the enamel contained nitrogen in concentrations similar to dentin, implicating that the protein content of the enamel is different from normal teeth where nitrogen is absent.

CONCLUSIONS

AS affects morphology and mineralization of enamel. It caused hypoplastic enamel and abnormal protein content in comparison to match-paired normal teeth. These findings show that AS also affects odontogenesis in addition to the known oral motor challenges.

Genomic Diagnosis for Pediatric Disorders: Revolution and Evolution

Powerful, recent advances in technologies to analyze the genome have had a profound impact on the practice of medical genetics, both in the laboratory and in the clinic. Increasing utilization of genome-wide testing such as chromosomal microarray analysis and exome sequencing have lead a shift toward a "genotype-first" approach. Numerous techniques are now available to diagnose a particular syndrome or phenotype, and while traditional techniques remain efficient tools in certain situations, higher-throughput technologies have become the de facto laboratory tool for diagnosis of most conditions. However, selecting the right assay or technology is challenging, and the wrong choice may lead to prolonged time to diagnosis, or even a missed diagnosis. In this review, we will discuss current core technologies for the diagnosis of classic genetic disorders to shed light on the benefits and disadvantages of these strategies, including diagnostic efficiency, variant interpretation, and secondary findings. Finally, we review upcoming technologies posed to impart further changes in the field of genetic diagnostics as we move toward "genome-first" practice.

State of the Art of Genetic Testing for Patients With Autism: A Practical Guide for Clinicians

The explosion in knowledge, technology, and clinical capabilities regarding genetics and genetic testing has expanded greatly in recent years, and these gains have rapidly been applied to individuals with autism spectrum disorder (ASD). However, most clinicians are unaware or confused in regards to whom to test, what tests to order, and how testing might alter management and improve outcomes. This review will address these issues. Research shows that ASD is highly genetic, and while monogenic cases are common, most patients have multiple genes interacting in disease pathogenesis. However, as genetics dictates disease risk, not outcomes, this does not exclude environmental factors. Clinically actionable genetics test results can be found across the phenotypically-heterogeneous ASD spectrum; thus recommendations are to test everyone. As ASD is also highly genetically heterogeneous, testing should address a wide range of variant types, including both large (historically detected by microarray) and small (detected by sequencing), at least across all genes (exome). Additional specialized testing important in ASD diagnostics includes fragile X, mitochondrial DNA, and pharmacogenetics; the latter often informative for which drug to order, at which dose. Recently, whole genome sequencing has emerged as a favorite since all of the above testing, and more, can be performed at a lower total cost than individual test orders. Trio (child plus parents) sequencing is often indicated, especially in more "severe" cases in order to find new (de novo) variants not present in either parent. Additionally, Angelman syndrome testing should be considered in appropriate cases. Current testing provides a precise diagnosis in many cases with ASD. Beyond diagnosis, genetic testing can oftentimes help elucidate potentially treatable risk factors that predispose the individual patient to develop disease. In this clinician's experience (RGB), this information leads to improved outcomes in as many as one-half of cases. Clinical improvement can occur in common associated ASD symptoms (attention, behavior, and anxiety) and/or in general systemtic symptoms (nausea, fatigue, pain), as demonstrated in brief case reports. Practical guidance is provided regarding assisting clinicians to choose the appropriate test(s) and laboratory, as well as how to get testing paid for. Recent cost reductions now allow for most families to benefit from genetic testing.

Differentiating molecular etiologies of Angelman syndrome through facial phenotyping using deep learning

Angelman syndrome (AS) is caused by several genetic mechanisms that impair the expression of maternally-inherited UBE3A through deletions, paternal uniparental disomy (UPD), UBE3A pathogenic variants, or imprinting defects. Current methods of differentiating the etiology require molecular testing, which is sometimes difficult to obtain. Recently, computer-based facial analysis systems have been used to assist in identifying genetic conditions based on facial phenotypes. We sought to understand if the facial-recognition system DeepGestalt could find differences in phenotype between molecular subtypes of AS. Images and molecular data on 261 individuals with AS ranging from 10 months through 32 years were analyzed by DeepGestalt in a cross-validation model with receiver operating characteristic (ROC) curves generated. The area under the curve (AUC) of the ROC for each molecular subtype was compared and ranked from least to greatest differentiable phenotype. We determined that DeepGestalt demonstrated a high degree of discrimination between the deletion subtype and UPD or imprinting defects, and a lower degree of discrimination with the UBE3A pathogenic variants subtype. Our findings suggest that DeepGestalt can recognize subclinical differences in phenotype based on etiology and may provide decision support for testing.

Clinical characteristics and epilepsy in genomic imprinting disorders: Angelman syndrome and Prader-Willi syndrome

Angelman syndrome (AS) and Prader-Willi syndrome (PWS) are considered sister imprinting disorders. Although both AS and PWS congenital neurodevelopmental disorders have chromosome 15q11.3-q13 dysfunction, their molecular mechanisms differ owing to genomic imprinting, which results in different parent-of-the-origin gene expressions. Recently, several randomized controlled trials have been proceeded to treat specific symptoms of AS and PWS. Due to the advance of clinical management, early diagnosis for patients with AS and PWS is important. PWS is induced by multiple paternal gene dysfunctions, including those in MKRN3, MAGEL2, NDN, SNURF-SNPRPN, NPAP1, and a cluster of small nucleolar RNA genes. PWS patients exhibit characteristic facial features, endocrinological, and behavioral phenotypes, including short and obese figures, hyperphagia, growth hormone deficiency, hypogonadism, autism, or obsessive- compulsive-like behaviors. In addition, hypotonia, poor feeding, failure to thrive, and typical facial features are major factors for early diagnosis of PWS. For PWS patients, epilepsy is not common and easy to treat. Conversely, AS is a single-gene disorder induced by ubiquitin-protein ligase E3A dysfunction, which only expresses from a maternal allele. AS patients develop epilepsy in their early lives and their seizures are difficult to control. The distinctive gait pattern, excessive laughter, and characteristic electroencephalography features, which contain anterior-dominated, high-voltage triphasic delta waves intermixed with epileptic spikes, result in early suspicion of AS. Often, polytherapy, including the combination of valproate, levetiracetam, lamotrigine, and benzodiazepines, is required for controlling seizures of AS patients. Notably, carbamazepine, oxcarbazepine, and vigabatrin should be avoided, since these may induce nonconvulsive status epilepticus. AS and PWS presented with distinct clinical manifestations according to specific molecular defects due to genomic imprinting. Early diagnosis and teamwork intervention, including geneticists, neurologists, rehabilitation physicians, and pulmonologists, are important. Epilepsy is common in patients with AS, and after proper treatment, seizures could be effectively controlled in late childhood or early adulthood for both AS and PWS patients.

Neurodevelopmental profile of siblings with Angelman syndrome due to pathogenic UBE3A variants

BACKGROUND

Angelman syndrome (AS) is a neurodevelopmental disorder caused by a lack of expression of the maternally inherited UBE3A gene on chromosome 15. Individuals with AS due to a UBE3A mutation are more likely to have siblings who also have AS compared with those with AS due to other cytogenetic/molecular mechanisms, but it is unknown whether the developmental outcome of siblings who have AS is similar.

METHODS

Through an ongoing AS Natural History Study, we identified seven pairs of siblings with AS due to a UBE3A mutation. We compared the neurodevelopment of the first-born and second-born siblings with AS participants who have a UBE3A mutation and have either typically developing siblings or no siblings.

RESULTS

Second-born AS participants due to a UBE3A mutation were more likely to be diagnosed at an earlier age. With the exception of higher expressive language scores among the second-born participants, no other differences were observed in the developmental and adaptive functioning skills across the different groups.

CONCLUSIONS

The presence of an older sibling with the same neurodevelopmental disorder is associated with an earlier age of diagnosis and may be associated with an improvement in expressive language skills; the developmental outcome of siblings with AS due to a UBE3A mutation is otherwise comparable.

Translational outcomes in a full gene deletion of ubiquitin protein ligase E3A rat model of Angelman syndrome

Angelman syndrome (AS) is a rare neurodevelopmental disorder characterized by developmental delay, impaired communication, motor deficits and ataxia, intellectual disabilities, microcephaly, and seizures. The genetic cause of AS is the loss of expression of UBE3A (ubiquitin protein ligase E6-AP) in the brain, typically due to a deletion of the maternal 15q11-q13 region. Previous studies have been performed using a mouse model with a deletion of a single exon of Ube3a. Since three splice variants of Ube3a exist, this has led to a lack of consistent reports and the theory that perhaps not all mouse studies were assessing the effects of an absence of all functional UBE3A. Herein, we report the generation and functional characterization of a novel model of Angelman syndrome by deleting the entire Ube3a gene in the rat. We validated that this resulted in the first comprehensive gene deletion rodent model. Ultrasonic vocalizations from newborn Ube3am-/p+ were reduced in the maternal inherited deletion group with no observable change in the Ube3am+/p- paternal transmission cohort. We also discovered Ube3am-/p+ exhibited delayed reflex development, motor deficits in rearing and fine motor skills, aberrant social communication, and impaired touchscreen learning and memory in young adults. These behavioral deficits were large in effect size and easily apparent in the larger rodent species. Low social communication was detected using a playback task that is unique to rats. Structural imaging illustrated decreased brain volume in Ube3am-/p+ and a variety of intriguing neuroanatomical phenotypes while Ube3am+/p- did not exhibit altered neuroanatomy. Our report identifies, for the first time, unique AS relevant functional phenotypes and anatomical markers as preclinical outcomes to test various strategies for gene and molecular therapies in AS.

Neuropsychopathology of Autism Spectrum Disorder: Complex Interplay of Genetic, Epigenetic, and Environmental Factors

Autism spectrum disorder (ASD) is a complex heterogeneous consortium of pervasive development disorders (PDD) which ranges from atypical autism, autism, and Asperger syndrome affecting brain in the developmental stage. This debilitating neurodevelopmental disorder results in both core as well as associated symptoms. Core symptoms observed in autistic patients are lack of social interaction, pervasive, stereotyped, and restricted behavior while the associated symptoms include irritability, anxiety, aggression, and several comorbid disorders.ASD is a polygenic disorder and is multifactorial in origin. Copy number variations (CNVs) of several genes that regulate the synaptogenesis and signaling pathways are one of the major factors responsible for the pathogenesis of autism. The complex integration of various CNVs cause mutations in the genes which code for molecules involved in cell adhesion, voltage-gated ion-channels, scaffolding proteins as well as signaling pathways (PTEN and mTOR pathways). These mutated genes are responsible for affecting synaptic transmission by causing plasticity dysfunction responsible, in turn, for the expression of ASD.Epigenetic modifications affecting DNA transcription and various pre-natal and post-natal exposure to a variety of environmental factors are also precipitating factors for the occurrence of ASD. All of these together cause dysregulation of glutamatergic signaling as well as imbalance in excitatory: inhibitory pathways resulting in glial cell activation and release of inflammatory mediators responsible for the aberrant social behavior which is observed in autistic patients.In this chapter we review and provide insight into the intricate integration of various genetic, epigenetic, and environmental factors which play a major role in the pathogenesis of this disorder and the mechanistic approach behind this integration.

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.

An observational study of pediatric healthcare burden in Angelman syndrome: results from a real-world study

BACKGROUND

The objective of this study is to describe variations in the healthcare resource utilization (HRU) among individuals with Angelman syndrome (AS) over the first 12 years of life. Data for this study were drawn from the AS Natural History study (ASNHS), which is an observational study on the developmental progress, behavior, and medical morbidity of individuals with AS conducted over eight years. Caregiver-reported information on hospitalization, surgery, and medication utilization was used to assess HRU. Repeated measures mixed effect models were used to assess the relationship between age and probability of hospitalization, surgery, and prescription medication utilization.

RESULTS

Mean age at study enrollment was 6 years of age and both sexes were equally represented. The mean number of visits per participant was three. Results from this study suggest that individuals with AS have a high HRU burden. Hospitalization and surgery burden were highest in the first year of life. Use of medications for seizures and sleep disturbance increased over time.

CONCLUSIONS

The study highlights the significant healthcare burden among individuals with AS. Future studies that estimate cost and caregiver burden associated with AS are needed to assess the lifelong economic impact of AS on families and healthcare system.

A mouse model of Angelman syndrome imprinting defects

Angelman syndrome, Prader-Will syndrome and Dup15q syndrome map to a cluster of imprinted genes located at 15q11-q13. Imprinting at this domain is regulated by an imprinting control region consisting of two distinct elements, the Angelman syndrome imprinting center (AS-IC) and the Prader-Willi syndrome imprinting center (PWS-IC). Individuals inheriting deletions of the AS-IC exhibit reduced expression of the maternally expressed UBE3A gene and biallelic expression of paternal-only genes. We have previously demonstrated that AS-IC activity partly consists of providing transcription across the PWS-IC in oocytes, and that these transcripts are necessary for maternal imprinting of Snrpn. Here we report a novel mouse mutation that truncates transcripts prior to transiting the PWS-IC and results in a domain-wide imprinting defect. These results confirm a transcription-based model for imprint setting at this domain. The imprinting defect can be preempted by removal of the transcriptional block in oocytes, but not by its removal in early embryos. Imprinting defect mice exhibit several traits often found in individuals with Angelman syndrome imprinting defects.

Healthcare burden among individuals with Angelman syndrome: Findings from the Angelman Syndrome Natural History Study

Background

The objective of this study is to describe healthcare resource utilization (HRU) and supportive therapy utilization (STU) among individuals with Angelman syndrome (AS), and to compare such usage by molecular etiology.

Methods

Participants were categorized into deletion and non‐deletion genotypes. Statistical differences were assessed using an independent samples t test.

Results

Data were available on 302 individuals. Mean age of participants was 5.5 years, 92% of whom were less than 13 years, and 71% had the deletion etiology. About 68% of participants had at least one hospitalization since birth to enrollment in the study; the average number of hospitalizations during that time period was 2.3 and average length of stay was 4.5 days. The most common reasons for hospitalization were seizures, lower respiratory infections, and surgery. The most common reasons for surgery were myringotomy, strabismus surgery, tonsillectomy or adenoidectomy, and gastrostomy tube insertion/fundoplication. Anticonvulsants, gastroesophageal reflux disease, sleep, and behavioral medications were the most commonly prescribed drugs. STU was high among individuals with AS.

Conclusions

This study shows that individuals with AS have high HRU/STU, and apart from a few differences, HRU/STU was similar across molecular etiology. These results reflect usage in younger individuals and studies that describe HRU/STU in older individuals are needed.

Maladaptive behaviors in individuals with Angelman syndrome

Maladaptive behaviors are challenging and a source of stress for caregivers of individuals with Angelman Syndrome (AS). There is limited information on how these maladaptive behaviors vary over time among individuals with AS due to different genetic etiologies. In this study, caregivers of 301 individuals with AS were asked questions about their child's behavior and completed the Aberrant Behavior Checklist-Community version (ABC-C). Developmental functioning was evaluated with either the Bayley Scales of Infant Development, Third Edition (Bayley-III) or the Mullen Scales of Early Learning (MSEL). Family functioning was assessed using the parent-completed Parenting Stress Index (PSI) and the Family Quality of Life questionnaire (FQoL). Approximately 70% of participants had AS due to a deletion on the maternally-inherited copy of chromosome 15q11q13. Results revealed that at baseline, individuals with AS had low scores in the domains of lethargy (mean: 2.6-4.2 depending on genotype) and stereotypy (mean: 2.3-4.2 depending on genotype). Higher cognitive functioning was associated with increased irritability (r = 0.32, p < .01). Hyperactivity (p < .05) and irritability (p < .05) increased with age across all genotypes and should be ongoing targets for both behavioral and pharmacological treatment. Concerns for short attention span were endorsed by more than 70% of caregivers at baseline. Maladaptive behaviors, particularly hyperactivity, irritability and aggression, adversely affected parental stress, and family quality of life.

Movement Disorders and Syndromic Autism: A Systematic Review

Movement disorders are reported in idiopathic autism but the extent to which comparable movement disorders are found in syndromic/co-morbid autism is unknown. A systematic search of Medline, Embase, PsychINFO and CINAHL on the prevalence of specific movement disorder in syndromic autism associated with specific genetic syndromes identified 16 papers, all relating to Angelman syndrome or Rett syndrome. Prevalence rates of 72.7-100% and 25.0-27.3% were reported for ataxia and tremor, respectively, in Angelman syndrome. In Rett syndrome, prevalence rates of 43.6-50% were reported for ataxia and 27.3-48.3% for tremor with additional reports of dystonia, rigidity and pyramidal signs. However, reliable assessment measures were rarely used and recruitment was often not described in sufficient detail.

Impaired proteostasis in rare neurological diseases

Rare diseases are classified as such when their prevalence is 1:2000 or lower, but even if each of them is so infrequent, altogether more than 300 million people in the world suffer one of the ∼7000 diseases considered as rare. Over 1200 of these disorders are known to affect the brain or other parts of our nervous system, and their symptoms can affect cognition, motor function and/or social interaction of the patients; we refer collectively to them as rare neurological disorders or RNDs. We have focused this review on RNDs known to have compromised protein homeostasis pathways. Proteostasis can be regulated and/or altered by a chain of cellular mechanisms, from protein synthesis and folding, to aggregation and degradation. Overall, we provide a list comprised of above 215 genes responsible for causing more than 170 distinct RNDs, deepening on some representative diseases, including as well a clinical view of how those diseases are diagnosed and dealt with. Additionally, we review existing methodologies for diagnosis and treatment, discussing the potential of specific deubiquitinating enzyme inhibition as a future therapeutic avenue for RNDs.

Hippocampal deficits in neurodevelopmental disorders

Neurodevelopmental disorders result from impaired development or maturation of the central nervous system. Both genetic and environmental factors can contribute to the pathogenesis of these disorders; however, the exact causes are frequently complex and unclear. Individuals with neurodevelopmental disorders may have deficits with diverse manifestations, including challenges with sensory function, motor function, learning, memory, executive function, emotion, anxiety, and social ability. Although these functions are mediated by multiple brain regions, many of them are dependent on the hippocampus. Extensive research supports important roles of the mammalian hippocampus in learning and cognition. In addition, with its high levels of activity-dependent synaptic plasticity and lifelong neurogenesis, the hippocampus is sensitive to experience and exposure and susceptible to disease and injury. In this review, we first summarize hippocampal deficits seen in several human neurodevelopmental disorders, and then discuss hippocampal impairment including hippocampus-dependent behavioral deficits found in animal models of these neurodevelopmental disorders.

Close yet so far away: a look into the management strategies of genetic imprinting disorders

Genetic imprinting is the process of epigenetic labelling or silencing of particular genes, based on the maternal or paternal origin of the gene, in a heritable pattern. The incidence of imprinting disorders has become a growing concern due to the potential association between these congenital syndromes and assisted reproductive technologies (ARTs). This review presents a general summary of the imprinting process as well as the current knowledge surrounding the genetic and epigenetic underpinnings of the most prevalent imprinting disorders: Beckwith-Wiedemann syndrome (BWS), Silver-Russell syndrome (SRS), Prader-Willi syndrome (PWS), and Angelman syndrome (AS). As research continues to elucidate the molecular pathways that characterize genetic imprinting, efforts have been made to establish guidelines that incorporate phenotypic manifestations as well as genetic testing to ensure safe and effective management of symptoms. While these efforts are likely to benefit future clinical management, their efficacy cannot yet be generalized to all patients diagnosed with these syndromes, as many of the genetic abnormalities and the associated phenotypic manifestations have yet to be characterized. Furthermore, future advances in the knowledge of epigenetic processes and genetic loci involved in the development of these syndromes may allow for the development of curative therapies.

Two Angelman families with unusually advanced neurodevelopment carry a start codon variant in the most highly expressed UBE3A isoform

We present three children from two unrelated families with Angelman syndrome (AS) whose developmental skills are far more advanced than any other non-mosaic AS individual ever reported. All have normal gait and use syntactic language spontaneously to express their needs. All of them have a c.2T > C (p.Met1Thr) variant in UBE3A, which abrogates the start codon of isoform 1, but not of isoforms 2 and 3. This variant was maternally inherited in one set of siblings, but de novo in the other child from the unrelated family. This report underscores the importance of considering AS in the differential diagnosis even in the presence of syntactic speech.