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Background Chromosome 15q11-q13 duplication syndrome (Dup15q) is a neurogenetic disorder caused by duplications of the maternal copy of this region. In addition to hypotonia, motor deficits, and language impairments, patients with Dup15q commonly meet the criteria for autism spectrum disorder and have a high prevalence of seizures. It is known from mouse models that synaptic impairments are a strong component of Dup15q pathophysiology; however, cellular phenotypes that relate to seizures are less clear. The development of patient-derived induced pluripotent stem cells provides a unique opportunity to study human neurons with the exact genetic disruptions that cause Dup15q. Methods Here, we explored electrophysiological phenotypes in induced pluripotent stem cell–derived neurons from 4 patients with Dup15q compared with 6 unaffected control subjects, 1 patient with a 15q11-q13 paternal duplication, and 3 patients with Angelman syndrome. Results We identified several properties of Dup15q neurons that could contribute to neuronal hyperexcitability and seizure susceptibility. Compared with control neurons, Dup15q neurons had increased excitatory synaptic event frequency and amplitude, increased density of dendritic protrusions, increased action potential firing, and decreased inhibitory synaptic transmission. Dup15q neurons also showed impairments in activity-dependent synaptic plasticity and homeostatic synaptic scaling. Finally, Dup15q neurons showed an increased frequency of spontaneous action potential firing compared with control neurons, in part due to disruption of KCNQ2 potassium channels. Conclusions Together, these data point to multiple electrophysiological mechanisms of hyperexcitability that may provide new targets for the treatment of seizures and other phenotypes associated with Dup15q.

Maternally inherited duplication of chromosome 15q11-q13 (Dup15q) is a pathogenic copy number variation (CNV) associated with autism spectrum disorder (ASD). Recently, paternally derived duplication has also been shown to contribute to the development of ASD. The molecular mechanism underlying paternal Dup15q remains unclear. Here, we conduct genetic and overexpression-based screening and identify Necdin (Ndn) as a driver gene for paternal Dup15q resulting in the development of ASD-like phenotypes in mice. An excess amount of Ndn results in enhanced spine formation and density as well as hyperexcitability of cortical pyramidal neurons. We generate 15q dupΔNdn mice with a normalized copy number of Ndn by excising its one copy from Dup15q mice using a CRISPR-Cas9 system. 15q dupΔNdn mice do not show ASD-like phenotypes and show dendritic spine dynamics and cortical excitatory-inhibitory balance similar to wild type animals. Our study provides an insight into the role of Ndn in paternal 15q duplication and a mouse model of paternal Dup15q syndrome., Duplication of chromosome 15q11-q13 is associated with autism spectrum disorder (ASD). Here, the authors show that in mice paternal Dup15q results in ASD-like neuronal and behavioural impairment driven by Necdin.

Background Duplication 15q (Dup15q) syndrome is a rare neurogenetic disorder characterized by autism and pharmacoresistant epilepsy. Most individuals with isodicentric duplications have been on multiple medications to control seizures. We recently developed a model of Dup15q in Drosophila by elevating levels of fly Dube3a in glial cells using repo-GAL4, not neurons. In contrast to other Dup15q models, these flies develop seizures that worsen with age. Methods We screened repo>Dube3a flies for approved compounds that can suppress seizures. Flies 3 to 5 days old were exposed to compounds in the fly food during development. Flies were tested using a bang sensitivity assay for seizure recovery time. At least 40 animals were tested per experiment, with separate testing for male and female flies. Studies of K+ content in glial cells of the fly brain were also performed using a fluorescent K+ indicator. Results We identified 17 of 1280 compounds in the Prestwick Chemical Library that could suppress seizures. Eight compounds were validated in secondary screening. Four of these compounds regulated either serotonergic or dopaminergic signaling, and subsequent experiments confirmed that seizure suppression occurred primarily through stimulation of serotonin receptor 5-HT1A. Additional studies of K+ levels showed that Dube3a regulation of the Na+/K+ exchanger ATPα (adenosine triphosphatase α) in glia may be modulated by serotonin/dopamine signaling, causing seizure suppression. Conclusions Based on these pharmacological and genetic studies, we present an argument for the use of 5-HT1A agonists in the treatment of Dup15q epilepsy.

BackgroundDuplications of 15q11.2-q13.1 (Dup15q syndrome) are highly penetrant for autism, intellectual disability, hypotonia, and epilepsy. The 15q region harbors genes critical for brain development, particularlyUBE3Aand a cluster of gamma-aminobutyric acid type A receptor (GABAAR) genes. We recently described an electrophysiological biomarker of the syndrome, characterized by excessive beta oscillations (12–30 Hz), resembling electroencephalogram (EEG) changes induced by allosteric modulation of GABAARs. In this follow-up study, we tested a larger cohort of children with Dup15q syndrome to comprehensively examine properties of this EEG biomarker that would inform its use in future clinical trials, specifically, its (1) relation to basic clinical features, such as age, duplication type, and epilepsy; (2) relation to behavioral characteristics, such as cognition and adaptive function; (3) stability over time; and (4) reproducibility of the signal in clinical EEG recordings.MethodsWe computed EEG power and beta peak frequency (BPF) in a cohort of children with Dup15q syndrome (N= 41, age range 9–189 months). To relate EEG parameters to clinical (study 1) and behavioral features (study 2), we examined age, duplication type, epilepsy, cognition, and daily living skills (DLS) as predictors of beta power and BPF. To evaluate stability over time (study 3), we derived the intraclass correlation coefficients (ICC) from beta power and BPF computed from children with multiple EEG recordings (N= 10, age range 18–161 months). To evaluate reproducibility in a clinical setting (study 4), we derived ICCs from beta power computed from children (N= 8, age range 19–96 months), who had undergone both research EEG and clinical EEG.ResultsThe most promising relationships between EEG and clinical traits were found using BPF. BPF was predicted both by epilepsy status (R2= 0.11,p= 0.038) and the DLS component of the Vineland Adaptive Behavior Scale (R2= 0.17,p= 0.01). Beta power and peak frequency showed high stability across repeated visits (beta power ICC = 0.93, BPF ICC = 0.92). A reproducibility analysis revealed that beta power estimates are comparable between research and clinical EEG (ICC = 0.94).ConclusionsIn this era of precision health, with pharmacological and neuromodulatory therapies being developed and tested for specific genetic etiologies of neurodevelopmental disorders, quantification and examination of mechanistic biomarkers can greatly improve clinical trials. To this end, the robust beta oscillations evident in Dup15q syndrome are clinically reproducible and stable over time. With future preclinical and computational studies that will help disentangle the underlying mechanism, it is possible that this biomarker could serve as a robust measure of drug target engagement or a proximal outcome measure in future disease modifying intervention trials.

Background Small supernumerary marker chromosomes (sSMCs), are additional abnormal chromosomes, which can’t be detected accurately by banding cytogenetic analysis. Abnormal phenotypes were observed in about 30% of SMC carriers. Duplication of chromosome 15 and related disorders, characterized by hypotonia motor delays, autism spectrum disorder (ASD), intellectual disability, and epilepsy including infantile spasms, might be account for 50% of the total sSMCs. Case presentation An 11-month-old infant with an sSMC found by banding cytogenetics was referred to our clinic because of developmental retardation and autism spectrum disorder. After several months of rehabilitation treatment, the progress of motor development was obvious, but the consciousness was still far from satisfied. High-resolution karyotype analysis, multiplex ligation-dependent probe amplification and copy number variation sequencing (CNV-Seq) were conducted to confirm the identity of the sSMC. A bisatellited dicentric sSMC was observed clearly in high-resolution karyotype analysis and a 10.16-Mb duplication of 15q11.1q13.2 (3.96 copies) together with a 1.84-Mb duplication of 15q13.2q13.3 (3 copies) was showed by CNV-Seq in the proband. It suggested that the molecular cytogenetic karyotype was 47,XY,+dic(15;15)(q13.2;q13.3). Furthermore, the clinical symptoms of the proband mostly fit 15q duplication related disorders which are characterized by hypotonia motor delays, autism spectrum disorder (ASD), and intellectual disability. Conclusion We reported for the first time using CNV-Seq to detect sSMCs and find a partial trisomy and tetrasomy of 15q11-q13 associated with developmental delay and autism spectrum disorder. Our report indicates that CNV-seq is a useful and economical way for diagnosis of dup15q and related disorders.

Background. The 15q11.1-13.1 duplication, also known as Dup15q syndrome, is a rare congenital disease affecting 1 in 30,000 to 1 in 60,000 children worldwide. This condition is characterized by the presence of at least one extra copy of genetical material within the Prader-Willi/Angelman Critical Region (PWACR) of the referred 15q11.2-q13.1 chromosome. Case Report. Our study presents the clinical and genetical features of the first patient with a denovo 15q11.2 interstitial duplication on the maternal allele (inv Dup15q) that mimics a milder Prader-Willi syndrome probably due to an atypical disruption of the SNHG14 gene. Methylation-specific MLPA analysis has confirmed the presence of a very unlikely duplication that lies between breakpoint 1 (BP1) and the middle of BP2 and BP3 (BP3). This atypical alteration might be linked to the milder patient’s clinical phenotype. Conclusions. This is the first Dup15q patient reported in Ecuador and of the very few in South America. This aberration has never been described in a patient with Dup15q, and the unusual clinical presentation is probably due to the atypical distal breakpoint occurring within the gene SNHG14 which lies between BP2 and BP3 and does not therefore contain the whole PWACR. If the duplication disrupted the gene, then it is possible that it is the cause of, or contributing to, the patient’s clinical phenotype.

The 15q duplication syndrome (dup15q) is due to the presence of at least one additional derived copy of the Prader–Willi syndrome/Angelman syndrome (PWS/AS) critical region that is approximately 5 Mb long within chromosome 15q11.2-q13.1. This report describes distinct roles of the origin of interstitial (int) dup15q underlining the critical importance of maternally active imprinted genes in the contribution to complete penetrance but different phenotypes of neuropsychotic disorders such as schizophrenia (SCZ) and autism spectrum disorder (ASD) in a Korean family. The proband’s mother as a consultant visited our hospital for her offspring’s genetic counseling and segregation analysis. She had two daughters diagnosed as SCZ or ASD and one son diagnosed as ASD. To resolve the potential genetic cause of SCZ and ASD in the proband and her sibling, whole genomic screening of chromosomal rearrangements by array-comparative genomic hybridization (CGH) was performed using SurePrint G3 Human CGH + SNP Microarray 4 × 180 K. Results of the array-CGH analysis revealed an interstitial duplication at 15q11.2-q13.1 (duplication size of 5.4 Mb) in the mother and her three offspring with SCZ or ASD. Our case, together with previous findings of high occurrence of psychotic disorder, suggest that maternally expressed gene product in the critical region of PWS/AS might mediate the risk of neurodevelopmental disorder (ASD) as well as psychotic disorder (SCZ). Multiple cytogenetic and molecular methods are recommended for investigating children with 15q11.2-q13.1 duplication and neuropsychotic disorders.

Transcriptomic analyses of postmortem brains have begun to elucidate molecular abnormalities in autism spectrum disorder (ASD). However, a crucial pathway involved in synaptic development, RNA editing, has not yet been studied on a genome-wide scale. Here we profiled global patterns of adenosine-to-inosine (A-to-I) editing in a large cohort of postmortem brains of people with ASD. We observed a global bias for hypoediting in ASD brains, which was shared across brain regions and involved many synaptic genes. We show that the Fragile X proteins FMRP and FXR1P interact with RNA-editing enzymes (ADAR proteins) and modulate A-to-I editing. Furthermore, we observed convergent patterns of RNA-editing alterations in ASD and Fragile X syndrome, establishing this as a molecular link between these related diseases. Our findings, which are corroborated across multiple data sets, including dup15q (genomic duplication of 15q11.2-13.1) cases associated with intellectual disability, highlight RNA-editing dysregulation in ASD and reveal new mechanisms underlying this disorder.

Background Sleep disturbances in autism spectrum disorder (ASD) represent a common and vexing comorbidity. Clinical heterogeneity amongst these warrants studies of the mechanisms associated with specific genetic etiologies. Duplications of 15q11.2-13.1 (Dup15q syndrome) are highly penetrant for neurodevelopmental disorders (NDDs) such as intellectual disability and ASD, as well as sleep disturbances. Genes in the 15q region, particularly UBE3A and a cluster of GABAA receptor genes, are critical for neural development, synaptic protein synthesis and degradation, and inhibitory neurotransmission. During awake electroencephalography (EEG), children with Dup15q syndrome demonstrate increased beta band oscillations (12–30 Hz) that likely reflect aberrant GABAergic neurotransmission. Healthy sleep rhythms, necessary for robust cognitive development, are also highly dependent on GABAergic neurotransmission. We therefore hypothesized that sleep physiology would be abnormal in children with Dup15q syndrome. Methods To test the hypothesis that elevated beta oscillations persist in sleep in Dup15q syndrome and that NREM sleep rhythms would be disrupted, we computed: (1) beta power, (2) spindle density, and (3) percentage of slow-wave sleep (SWS) in overnight sleep EEG recordings from a cohort of children with Dup15q syndrome (n = 15) and compared them to age-matched neurotypical children (n = 12). Results Children with Dup15q syndrome showed abnormal sleep physiology with elevated beta power, reduced spindle density, and reduced or absent SWS compared to age-matched neurotypical controls. Limitations This study relied on clinical EEG where sleep staging was not available. However, considering that clinical polysomnograms are challenging to collect in this population, the ability to quantify these biomarkers on clinical EEG—routinely ordered for epilepsy monitoring—opens the door for larger-scale studies. While comparable to other human studies in rare genetic disorders, a larger sample would allow for examination of the role of seizure severity, medications, and developmental age that may impact sleep physiology. Conclusions We have identified three quantitative EEG biomarkers of sleep disruption in Dup15q syndrome, a genetic condition highly penetrant for ASD. Insights from this study not only promote a greater mechanistic understanding of the pathophysiology defining Dup15q syndrome, but also lay the foundation for studies that investigate the association between sleep and cognition. Abnormal sleep physiology may undermine healthy cognitive development and may serve as a quantifiable and modifiable target for behavioral and pharmacological interventions.

Objective We aimed to describe epilepsy and EEG patterns related to vigilance states and age, in chromosome15-long-arm-duplication-syndrome (dup15q) children with epilepsy, in both duplication types: interstitial (intdup15) and isodicentric (idic15). Methods Clinical data and 70 EEGs of 12 patients (5 intdup15, 7 idic15), followed from 4.5 m.o to 17y4m (median follow-up 8y3m), were retrospectively reviewed. EEGs were analyzed visually and using power spectrum analysis. Results Seventy video-EEGs were analyzed (1–16 per patient, median 6), follow-up lasting up to 8y10m (median 4y2m): 25 EEGs in intdup15 (8 m.o to 12y.o, median 4y6m) and 45 EEGs in idic15 (7 m.o to 12 y.o, median 15 m). Epilepsy: 6 West syndrome (WS) (2intdup15, 4idic15); 4 Lennox-Gastaut syndromes (LGS) (1 intdup15, 3 idic15), 2 evolving from WS; focal epilepsy (3 intdup15). In idic15, WS displayed additional myoclonic seizures (3), atypical (4) or no hypsarrhythmia (2) and posterior predominant spike and polyspike bursts (4). Beta-band rapid-rhythms (RR): present in 11 patients, power decreased during non-REM-sleep, localization shifted from diffuse to anterior, peak frequency increased with age. Conclusion WS with peculiar electro-clinical features and LGS, along with beta-band RR decreasing in non-REM-sleep and shifting from diffuse to anterior localization with age are recognizable features pointing towards dup15q diagnosis in children with autism spectrum disorder and developmental delay. Significance This study describes electroclinical features in both interstitial and isodicentric duplications of chromosome 15q, in epileptic children, including some recent extensions regarding sleep features; and illustrates how the temporo-spatial organization of beta oscillations can be of significant help in directing towards dup15q diagnosis hypothesis.

Chromosome 15 (C15) imprinting disorders including Prader–Willi (PWS), Angelman (AS) and chromosome 15 duplication (Dup15q) syndromes are severe neurodevelopmental disorders caused by abnormal expression of genes from the 15q11–q13 region, associated with abnormal DNA methylation and/or copy number changes. This study compared changes in mRNA levels of UBE3A and SNORD116 located within the 15q11–q13 region between these disorders and their subtypes and related these to the clinical phenotypes. The study cohort included 58 participants affected with a C15 imprinting disorder (PWS = 27, AS = 21, Dup15q = 10) and 20 typically developing controls. Semi-quantitative analysis of mRNA from peripheral blood mononuclear cells (PBMCs) was performed using reverse transcription droplet digital polymerase chain reaction (PCR) for UBE3A and SNORD116 normalised to a panel of internal control genes determined using the geNorm approach. Participants completed an intellectual/developmental functioning assessment and the Autism Diagnostic Observation Schedule-2nd Edition. The Dup15q group was the only condition with significantly increased UBE3A mRNA levels when compared to the control group (p SNORD116 mRNA levels compared to controls (AS: p p = 0.002). Both UBE3A and SNORD116 mRNA levels were positively correlated with all developmental functioning scores in the deletion AS group (p p UBE3A and SNORD116 in PBMCs and brain specific processes underlying motor and language impairments and autism features in these disorders.

Background Comorbidity is the presence of at least two disorders in one person at one time. This study examined the frequency of gastrointestinal (GI) symptoms, sleep problems, comorbid psychopathology, challenging behaviour and autism spectrum disorder (ASD) symptoms in children and adolescents with duplication 15q syndrome (Dup15q), aged 3-17 years. This study also examined whether challenging behaviour in Dup15q is predicted by age, gender, presence of an intellectual disability, sleep problems, GI symptoms and comorbid psychopathology. Method Parental measures were completed by 101 parents of children and adolescents with Dup15q. Questionnaires were composed of the Children's Sleep Habits Questionnaire, Behavior Problems Inventory - Short Form, GI Symptom Inventory, Social Communication Questionnaire and the Child Behavior Checklist. Results Sleep problems (94%), GI symptoms (87%) and challenging behaviour (100%) were common comorbidities represented in the sample in this study. Significant relationships were found between challenging behaviour and the presence of co-occurring sleep problems, GI symptoms, comorbid psychopathology and ASD symptoms. Further analysis revealed that these comorbidities also predicted challenging behaviour. Conclusion This research demonstrated the importance of studying the relationships between GI symptoms, sleep problems, comorbid psychopathology, ASD symptoms and challenging behaviour in Dup15q and how these conditions can shape the Dup15q phenotype.

Motor impairments occur frequently in genetic syndromes highly penetrant for autism spectrum disorder (syndromic ASD) and in individuals with ASD without a genetic diagnosis (nonsyndromic ASD). In particular, abnormalities in gait in ASD have been linked to language delay, ASD severity, and likelihood of having a genetic disorder. Quantitative measures of motor function can improve our ability to evaluate motor differences in individuals with syndromic and nonsyndromic ASD with varying levels of intellectual disability and adaptive skills. To evaluate this methodology, we chose to use quantitative gait analysis to study duplication 15q syndrome (dup15q syndrome), a genetic disorder highly penetrant for motor delays, intellectual disability, and ASD. We evaluated quantitative gait variables in individuals with dup15q syndrome (n = 39) and nonsyndromic ASD (n = 21) and compared these data to a reference typically developing cohort. We found a gait pattern of slow pace, poor postural control, and large gait variability in dup15q syndrome. Our findings improve characterization of motor function in dup15q syndrome and nonsyndromic ASD. Quantitative gait analysis can be used as a translational method and can improve our identification of clinical endpoints to be used in treatment trials for these syndromes. Autism Res 2020, 13: 1102-1110. © 2020 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Motor impairments, particularly abnormalities in walking, occur frequently in genetic syndromes highly penetrant for autism spectrum disorder (syndromic ASD). Here, using quantitative gait analysis, we find that individuals with duplication 15q syndrome have an atypical gait pattern that differentiates them from typically developing and nonsyndromic ASD individuals. Our findings improve motor characterization in dup15q syndrome and nonsyndromic ASD.

Epilepsy affects millions of individuals worldwide and many cases are pharmacoresistant. Duplication 15q syndrome (Dup15q) is a genetic disorder caused by duplications of the 15q11.2-q13.1 region. Phenotypes include a high rate of pharmacoresistant epilepsy. We developed a Dup15q model in Drosophila melanogaster that recapitulates seizures in Dup15q by over-expressing fly Dube3a or human UBE3A in glial cells, but not neurons, implicating glia in the Dup15q epilepsy phenotype. We compared Dube3a overexpression in glia (repo>Dube3a) versus neurons (elav>Dube3a) using transcriptomics and proteomics of whole fly head extracts. We identified 851 transcripts differentially regulated in repo>Dube3a, including an upregulation of glutathione S-transferase (GST) genes that occurred cell autonomously within glial cells. We reliably measured approximately 2,500 proteins by proteomics, most of which were also quantified at the transcript level. Combined transcriptomic and proteomic analysis revealed an enrichment of 21 synaptic transmission genes downregulated at the transcript and protein in repo>Dube3a indicating synaptic proteins change in a cell non-autonomous manner in repo>Dube3a flies. We identified 6 additional glia originating bang-sensitive seizure lines and found upregulation of GSTs in 4 out of these 6 lines. These data suggest GST upregulation is common among gliopathic seizures and may ultimately provide insight for treating epilepsy.

Purpose Dup15q syndrome is a rare genetic disease with a fairly nonspecific phenotype, clinical heterogeneity, and a wide spectrum of severity. However, no formal characterization has been attempted to select clusters of symptoms, signs and instrumental tests, to be used in the differential diagnosis with other neurodevelopmental disorders. Thus, our purpose was to identify symptoms, signs and instrumental findings, singly or in various combinations, favoring the early diagnosis of the Dup15q syndrome and the indication for genetic testing. Methods 25 patients with Dup15q syndrome and 25 age and sex matched controls with other neurodevelopmental disorders were the study population. Patients’ history, clinical and instrumental assessment were examined by five expert child neurologists blind to the genetic diagnosis. Each rater was asked to make the diagnosis in three subsequent steps: 1. Revision of the medical records; 2. Examination of the videorecorded clinical findings; 3. Assessment of the instrumental tests. Inter-rater agreement was measured with the Kendall’s coefficient of concordance) and the Kappa statistic. Sensitivity, specificity and predictive values for symptoms, signs and instrumental findings, singly or in various combinations, were measured. Results The Kendall’s coefficient for the diagnosis of Dup15q syndrome was 0.43 at step 1 was 0.43, at step 2 was 0.42, at step 3. Patients with past feeding difficulties, hypotonia during the neonatal period, and epilepsy had >80 % probability of having the Dup15q syndrome. Conclusion Feeding difficulties, hypotonia and epilepsy, though unspecific, can be used as signals of Dup15q syndrome and focused search of genetic abnormalities.

Maternally derived copy number gains of human chromosome 15q11.2-q13.3 (Dup15q syndrome or Dup15q) cause intellectual disability, epilepsy, developmental delay, hypotonia, speech impairments, and minor dysmorphic features. Dup15q syndrome is one of the most common and penetrant chromosomal abnormalities observed in individuals with autism spectrum disorder (ASD). Although ∼40 genes are located in the 15q11.2-q13.3 region, overexpression of the ubiquitin-protein E3A ligase (UBE3A) gene is thought to be the predominant molecular cause of the phenotypes observed in Dup15q syndrome. The UBE3A gene demonstrates maternal-specific expression in neurons and loss of maternal UBE3A causes Angelman syndrome, a neurodevelopmental disorder with some overlapping neurological features to Dup15q. To directly test the hypothesis that overexpression of UBE3A is an important underlying molecular cause of neurodevelopmental dysfunction, we developed and characterized a mouse overexpressing Ube3a isoform 2 in excitatory neurons. Ube3a isoform 2 is conserved between mouse and human and known to play key roles in neuronal function. Transgenic mice overexpressing Ube3a isoform 2 in excitatory forebrain neurons exhibited increased anxiety-like behaviors, learning impairments, and reduced seizure thresholds. However, these transgenic mice displayed normal social approach, social interactions, and repetitive motor stereotypies that are relevant to ASD. Reduced forebrain, hippocampus, striatum, amygdala, and cortical volume were also observed. Altogether, these findings show neuronal overexpression of Ube3a isoform 2 causes phenotypes translatable to neurodevelopmental disorders.

Duplication of chromosome 15q11.2-q13.1 (dup15q syndrome) results in hypotonia, intellectual disability (ID), and autism symptomatology. Clinical electroencephalography has shown abnormal sleep physiology, but no studies have characterized sleep behaviors. The present study used the Children's Sleep Habits Questionnaire (CSHQ) in 42 people with dup15q syndrome to examine the clinical utility of this questionnaire and quantify behavioral sleep patterns in dup15q syndrome. Individuals with fully completed forms (56%) had higher cognitive abilities than those with partially completed forms. Overall, caregivers indicated a high rate of sleep disturbance, though ratings differed by epilepsy status. Results suggest that clinicians should use caution when using standardized questionnaires and consider epilepsy status when screening for sleep problems in dup15q syndrome.

Background Duplications of 15q11.2-q13.1 (Dup15q syndrome), including the paternally imprinted gene UBE3A and three nonimprinted gamma-aminobutyric acid type-A (GABAA) receptor genes, are highly penetrant for neurodevelopmental disorders such as autism spectrum disorder (ASD). To guide targeted treatments of Dup15q syndrome and other forms of ASD, biomarkers are needed that reflect molecular mechanisms of pathology. We recently described a beta EEG phenotype of Dup15q syndrome, but it remains unknown which specific genes drive this phenotype. Methods To test the hypothesis that UBE3A overexpression is not necessary for the beta EEG phenotype, we compared EEG from a reference cohort of children with Dup15q syndrome (n = 27) to (1) the pharmacological effects of the GABAA modulator midazolam (n = 12) on EEG from healthy adults, (2) EEG from typically developing (TD) children (n = 14), and (3) EEG from two children with duplications of paternal 15q (i.e., the UBE3A-silenced allele). Results Peak beta power was significantly increased in the reference cohort relative to TD controls. Midazolam administration recapitulated the beta EEG phenotype in healthy adults with a similar peak frequency in central channels (f = 23.0 Hz) as Dup15q syndrome (f = 23.1 Hz). Both paternal Dup15q syndrome cases displayed beta power comparable to the reference cohort. Conclusions Our results suggest a critical role for GABAergic transmission in the Dup15q syndrome beta EEG phenotype, which cannot be explained by UBE3A dysfunction alone. If this mechanism is confirmed, the phenotype may be used as a marker of GABAergic pathology in clinical trials for Dup15q syndrome. Electronic supplementary material The online version of this article (10.1186/s13229-019-0280-6) contains supplementary material, which is available to authorized users.

Following publication of the original article [1], we have been notified that the Ethics statement of the articles should be changed. The Ethics statement now reads

Parents of children with chromosome 15q duplication syndrome (Dup15q) have anecdotally reported high pain threshold as a feature of the disorder. The purpose of this study was to document parental-reported estimates of the frequency of high pain tolerance and the stimuli that fail to evoke a normal pain response. We sent an online survey to 840 families with children with Dup15q to explore the frequency and clinical manifestations of high pain threshold. There were 216 respondents (25.7%). A high pain threshold was reported in 87% of children at some time. There was a trend (p=0.06) for high pain threshold to be more commonly observed among children with the isodicentric (85.6%) and other genetic variants (95%) than interstitial (69.6%) duplications. There was no association between reports of high pain threshold and reports of an intellectual disability (91% of cases), autism spectrum disorder (83% of cases), or self-injurious behavior (40% of cases). Reports included many dramatic cases such as severe burns, broken bones, and electrical traumas, which were associated with little or no evidence of a painful stimulus. A high pain threshold is reported in other disorders associated with intellectual disability and autism; the underlying mechanism in Dup15q and other disorders remains undefined.

Chromosome 15q11-q13 duplication syndrome (Dup15q) is a neurogenetic disorder caused by duplications of the maternal copy of this region. In addition to hypotonia, motor deficits, and language impairments, Dup15q patients commonly meet the criteria for autism spectrum disorder (ASD) and have a high prevalence of seizures. Here, we explored mechanisms of hyperexcitability in neurons derived from induced pluripotent stem cell (iPSC) lines from Dup15q patients. Maturation of resting membrane potential in Dup15q-derived neurons was similar to neurons from unaffected control subjects, but Dup15q neurons had delayed action potential maturation and increased synaptic event frequency and amplitude. Dup15q neurons also showed impairments in activity-dependent synaptic plasticity and homeostatic synaptic scaling. Finally, Dup15q neurons showed an increased frequency of spontaneous action potential firing compared to control neurons, in part due to disruption of KCNQ2 channels. Together these data point to multiple mechanisms underlying hyperexcitability that may provide new targets for the treatment of seizures and other phenotypes associated with Dup15q.

Objective We studied our collective open-label, compassionate use experience in using cannabidiol (CBD) to treat epilepsy in patients with CDKL5 deficiency disorder and Aicardi, Doose, and Dup15q syndromes. Methods We included patients aged 1–30 years with severe childhood-onset epilepsy who received CBD for ≥10 weeks as part of multiple investigator-initiated expanded access or state access programs for a compassionate prospective interventional study: CDKL5 deficiency disorder (n = 20), Aicardi syndrome (n = 19), Dup15q syndrome (n = 8), and Doose syndrome (n = 8). These patients were treated at 11 institutions from January 2014 to December 2016. Results The percent change in median convulsive seizure frequency for all patients taking CBD in the efficacy group decreased from baseline [n = 46] to week 12 (51.4% [n = 35], interquartile range (IQR): 9–85%) and week 48 (59.1% [n = 27], IQR: 14–86%). There was a significant difference between the percent changes in monthly convulsive seizure frequency during baseline and week 12, χ2(2) = 22.9, p = 0.00001, with no difference in seizure percent change between weeks 12 and 48. Of the 55 patients in the safety group, 15 (27%) withdrew from extended observation by week 144: 4 due to adverse effects, 9 due to lack of efficacy, 1 withdrew consent, and 1 was lost to follow-up. Significance This open-label drug trial provides class III evidence for the long-term safety and efficacy of CBD administration in patients with treatment-resistant epilepsy (TRE) associated with CDKL5 deficiency disorder and Aicardi, Dup15q, and Doose syndromes. Adjuvant therapy with CBD showed similar safety and efficacy for these four syndromes as reported in a diverse population of TRE etiologies. This study extended analysis of the prior report from 12 weeks to 48 weeks of efficacy data and suggested that placebo-controlled randomized trials should be conducted to formally assess the safety and efficacy of CBD in these epileptic encephalopathies.

Background The inability to analyze gene expression in living neurons from Angelman (AS) and Duplication 15q (Dup15q) syndrome subjects has limited our understanding of these disorders at the molecular level. Method Here, we use dental pulp stem cells (DPSC) from AS deletion, 15q Duplication, and neurotypical control subjects for whole transcriptome analysis. We identified 20 genes unique to AS neurons, 120 genes unique to 15q duplication, and 3 shared transcripts that were differentially expressed in DPSC neurons vs controls. Results Copy number correlated with gene expression for most genes across the 15q11.2-q13.1 critical region. Two thirds of the genes differentially expressed in 15q duplication neurons were downregulated compared to controls including several transcription factors, while in AS differential expression was restricted primarily to the 15q region. Here, we show significant downregulation of the transcription factors FOXO1 and HAND2 in neurons from 15q duplication, but not AS deletion subjects suggesting that disruptions in transcriptional regulation may be a driving factor in the autism phenotype in Dup15q syndrome. Downstream analysis revealed downregulation of the ASD associated genes EHPB2 and RORA, both genes with FOXO1 binding sites. Genes upregulated in either Dup15q cortex or idiopathic ASD cortex both overlapped significantly with the most upregulated genes in Dup15q DPSC-derived neurons. Conclusions Finding a significant increase in both HERC2 and UBE3A in Dup15q neurons and significant decrease in these two genes in AS deletion neurons may explain differences between AS deletion class and UBE3A specific classes of AS mutation where HERC2 is expressed at normal levels. Also, we identified an enrichment for FOXO1-regulated transcripts in Dup15q neurons including ASD-associated genes EHPB2 and RORA indicating a possible connection between this syndromic form of ASD and idiopathic cases. Electronic supplementary material The online version of this article (10.1186/s13229-018-0191-y) contains supplementary material, which is available to authorized users.

Patients with 15q duplication syndromes, including isodicentric chromosome 15 and interstitial duplications, usually present with autism spectrum disorder, intellectual disability, and frequently epilepsy. Neuroimaging studies in these patients are typically reported as normal, but nonspecific findings such as thinning of the corpus callosum and increased pericerebral spaces have been reported. A review of brain magnetic resonance imaging (MRI) studies of 11 individuals seen at the Massachusetts General Hospital Dup15q Center was performed. Hippocampus morphology was specifically reviewed, as a recent neuropathologic study has found frequent hippocampal heterotopias and dysplasias in these disorders. Two subjects had unilateral hippocampal sclerosis and 6 had bilateral hippocampal malformations. Hypoplasia of the corpus callosum was present in 2 subjects.

Background Autism Spectrum Disorder (ASD) includes a spectrum of genetically and clinically complex neurodevelopmental disorders. Findings from recent discordant monozygotic twins and post-mortem brain studies suggest that altered epigenetic processes, including DNA methylation and histone acetylation, are involved in the etiology of ASD. This study presents, to our knowledge, the largest post-mortem genome-wide DNA methylation analyses of autism patients, including idiopathic ASD and chromosome 15q11.2-13.1 duplication syndrome (dup15q) carriers, and matched controls. Methods We performed methylomic profiling in human post-mortem brain tissues using samples from three brain regions (dorsolateral prefrontal cortex, primary auditory cortex and cerebellum) of idiopathic autism cases, dup15q cariers and matched controls using the Illumina Infinium HumanMethylation450 array. Following stringent quality control and data pre-processing ASD-associated differential methylation analyses were performed at both probe-wise and region-wise levels. Results Our analyses revealed ASD-associated dysregulation of DNA methylation at multiple loci, with a large number of cross-cortex significant differentially methylated probes. In addition, although the differential methylation observed in dup15q samples were much more pronounced than those from iASD samples, we observed a convergent of methylomic signatures between autism associated with duplications of chromosome 15q and idiopathic autism. Discussion This epigenome-wide study of autism using post-mortem tissues represents the most comprehensive study to date. Findings from this study further support a role of altered epigenetics signatures in ASD and provide novel insight that idiopathic ASD and a genetically defined form of ASD (i.e. dup15q) carry similar underlying epigenetics changes.

Chromosomal copy number variants (CNV) are the most common genetic lesion found in autism. Many autism-associated CNVs are duplications of chromosome 15q. Although most cases of interstitial (int) dup(15) that present clinically are de novo and maternally derived or inherited, both pathogenic and unaffected paternal duplications of 15q have been identified. We performed a phenotype/genotype analysis of individuals with interstitial 15q duplications to broaden our understanding of the 15q syndrome and investigate the contribution of 15q duplication to increased autism risk. All subjects were recruited solely on the basis of interstitial duplication 15q11.2-q13 status. Comparative array genome hybridization was used to determine the duplication size and boundaries while the methylation status of the maternally methylated small nuclear ribonucleoprotein polypeptide N gene was used to determine the parent of origin of the duplication. We determined the duplication size and parental origin for 14 int dup(15) subjects: 10 maternal and 4 paternal cases. The majority of int dup(15) cases recruited were maternal in origin, most likely due to our finding that maternal duplication was coincident with autism spectrum disorder. The size of the duplication did not correlate with the severity of the phenotype as established by Autism Diagnostic Observation Scale calibrated severity score. We identified phenotypes not comprehensively described before in this cohort including mild facial dysmorphism, sleep problems and an unusual electroencephalogram variant. Our results are consistent with the hypothesis that the maternally expressed ubiquitin protein ligase E3A gene is primarily responsible for the autism phenotype in int dup(15) since all maternal cases tested presented on the autism spectrum.

Our objective was to define the EEG features during sleep of children with neurodevelopmental disorders due to copy number gains of 15q11-q13 (Dup15q). We retrospectively reviewed continuous EEG recordings of 42 children with Dup15q (mean age: eight years, 32 with idic15), and data collected included background activity, interictal epileptiform discharges, sleep organization, and ictal activity. Three patterns were recognized: Pattern 1: Alpha–delta sleep was noted in 14 children (33%), not associated with any clinical changes. Pattern 2: Electrical status epilepticus in sleep was noted in 15 children (35%), all diagnosed with treatmentresistant epilepsy. Thirteen of the 15 children had clinical seizures. Pattern 3: Frequent bursts of high amplitude bifrontal predominant, paroxysmal fast activity (12–15 Hz) during non-REM sleep was noted in 15 children (35%). All 15 children had treatment-resistant epilepsy. This is the first report of electroencephalographic patterns during sleep of children with Dup15q reporting alpha-delta rhythms, CSWS, and high amplitude fast frequencies. Alpha-delta rhythms are described in children with dysautonomia and/or mood disorders and CSWS in children with developmental regression. The significance of these findings in cognitive function and epilepsy for the children in our cohort needs to be determined with follow-up studies.

BackgroundOne of the most common genetic variants associated with autism spectrum disorder (ASD) are duplications of chromosome 15q11.2-q13.1 (Dup15q syndrome). To identify distinctive developmental and behavioral features in Dup15q syndrome, we examined the social communication, adaptive, and cognitive skills in clinic-referred subjects and compared the characteristics of children with Dup15q syndrome to age/IQ-matched children with non-syndromic ASD. Behavior and development were also analyzed within the Dup15q group for differences related to copy number or epilepsy.MethodsParticipants included 13 children with Dup15q syndrome and 13 children with non-syndromic ASD, matched on chronological and mental age, ages 22months-12years. In the Dup15q group, ten participants had isodicentric and three had interstitial duplications. Four children had active epilepsy (all isodicentric). Participants were assessed for verbal and non-verbal cognition, ASD characteristics based on the Autism Diagnostic Observation Schedule (ADOS), and adaptive function based on the Vineland Adaptive Behavior Scales (VABS). Group comparisons were performed between Dup15q and ASD participants, as well as within the Dup15q group based on duplication type and epilepsy status.ResultsAll children with Dup15q syndrome met the criteria for ASD; ASD severity scores were significantly lower than children in the non-syndromic ASD group. ADOS profiles demonstrated a relative strength in items related to social interest. Children with Dup15q syndrome also demonstrated significantly more impairment in motor and daily living skills. Within the Dup15q group, children with epilepsy demonstrated significantly lower cognitive and adaptive function than those without epilepsy.ConclusionsThe relative strength observed in social interest and responsiveness in the context of impaired motor skills represents an important avenue for intervention, including aggressive treatment of epilepsy, early and consistent focus on motor skills, and intervention targeting joint attention and language within a play context, in order to build on social interest to further develop social communication abilities. Longitudinal research beginning in early development will elucidate the temporal relationships between developmental domains and neurological comorbidities in these children at high risk for neurodevelopmental disorders.

Persistent organic pollutants (POPs), including polychlorinated biphenyls (PCBs) and polybrominated diphenylethers (PBDEs) that bioaccumulate in lipid-rich tissues are of concern as developmental neurotoxicants. Epigenetic mechanisms such as DNA methylation act at the interface of genetic and environmental factors implicated in autism-spectrum disorders. The relationship between POP levels and DNA methylation patterns in individuals with and without neurodevelopmental disorders has not been previously investigated. In this study, a total of 107 human frozen postmortem brain samples were analyzed for eight PCBs and seven PBDEs by GC-micro electron capture detector and GC/MS using negative chemical ionization. Human brain samples were grouped as neurotypical controls (n = 43), neurodevelopmental disorders with known genetic basis (n = 32, including Down, Rett, Prader-Willi, Angelman, and 15q11-q13 duplication syndromes), and autism of unknown etiology (n = 32). Unexpectedly, PCB 95 was significantly higher in the genetic neurodevelopmental group, but not idiopathic autism, as compared to neurotypical controls. Interestingly, samples with detectable PCB 95 levels were almost exclusively those with maternal 15q11-q13 duplication (Dup15q) or deletion in Prader-Willi syndrome. When sorted by birth year, Dup15q samples represented five out of six of genetic neurodevelopmental samples born after the 1976 PCB ban exhibiting detectable PCB 95 levels. Dup15q was the strongest predictor of PCB 95 exposure over age, gender, or year of birth. Dup15q brain showed lower levels of repetitive DNA methylation measured by LINE-1 pyrosequencing, but methylation levels were confounded by year of birth. These results demonstrate a novel paradigm by which specific POPs may predispose to genetic copy number variation of 15q11-q13.

Purpose To ascertain the cause of mortality and incidence of sudden unexpected death in epilepsy (SUDEP) in patients with supernumerary isodicentric chromosome 15 (idic15). Methods Cases were obtained from those reported to the Dup15q Alliance ( www.dup15q.org ) between April 2006 and June 2012; ~ 709 families were registered in their database. We performed a case–control study comparing reported SUDEP cases to living patients with epilepsy from the Dup15q Alliance registry who volunteered to be interviewed to examine clinical risk factors. Key findings There were nineteen deaths with idic15; 17 had epilepsy, and nine deaths were due to probable or definite SUDEP (4 females, median age of death was 13.5 years, range: 3–26 years). Possible SUDEP occurred in 2 others. The remainder died from status epilepticus (3), pneumonia (3), aspiration (1), and drowning (1). Nonambulatory status and lack of seizure control were more common among SUDEP cases than living dup15q patients. Significance Our findings suggest that SUDEP is a common cause of death among children and young adults with isodicentric chromosome 15q11.2q13 duplications and patients with the most severe neurologic dysfunction may be at highest risk. Further studies are needed to examine if this specific genetic defect plays a role in the mechanism of SUDEP in these patients.

Idic(15) syndrome is a neurogenetic disorder clinically delineated by early central hypotonia, developmental delay and intellectual disability (ID), epilepsy, absent or very poor speech, and autistic or autistic-like behavior. It is due to the presence of a supernumerary marker chromosome formed by the inverted duplication of proximal chromosome 15, resulting in tetrasomy 15p and partial tetrasomy 15q, and containing the Prader-Willi/Angelman syndrome critical region (PWS/ASCR). The vast majority of these idic(15) derives from the two homologous maternal chromosomes at meiosis. To better define the behavior profile, we studied 22 idic(15) children (15 males and 7 females) observed at our institute between 1986 and 2010, and present, in detail, case studies of five of them. We have been able to perform standardized and semi-standardized measures of intelligence, and psychopathology in only 13 of our 22 patients, due to the limitations of chronological age, and to the severity of ID (ranging from mild-moderate, in 15%, to severe-profound, in 85% of our sample). The results show a distinct developmental profile in idic(15) patients, that may provide a behavioral signature for autism spectrum disorder (ASD)/ASD-like arising from the susceptibility locus on proximal 15q; and suggest that idic(15) individuals are not "true autistic," but distinct "autistic-like" persons with high score in the third ADOS-G and ADI-R area.

Background: Chromosome 15q11.2-q13.1 duplication syndrome (Dup15q syndrome) is a rare disorder caused by duplications of chromosome 15q11.2-q13.1, resulting in a wide range of developmental disabilities in affected individuals. The Dup15q Alliance is an organization that provides family support and promotes research to improve the quality of life of patients living with Dup15q syndrome. Because of the low prevalence of this condition, the establishment of a single research repository would have been difficult and more time consuming without collaboration across multiple institutions. Objective: The goal of this project is to establish a national deidentified database with clinical and survey information on individuals diagnosed with Dup15q syndrome. Methods: The development of a multiclinic site repository for clinical and survey data on individuals with Dup15q syndrome was initiated and supported by the Dup15q Alliance. Using collaborative workflows, communication protocols, and stakeholder engagement tools, a comprehensive database of patient-centered information was built. Results: We successfully established a self-report populating, centralized repository for Dup15q syndrome research. This repository also resulted in the development of standardized instruments that can be used for other studies relating to developmental disorders. By standardizing the data collection instruments, it allows us integrate our data with other national databases, such as the National Database for Autism Research. A substantial portion of the data collected from the questionnaires was facilitated through direct engagement of participants and their families. This allowed for a more complete set of information to be collected with a minimal turnaround time. Conclusions: We developed a repository that can efficiently be mined for shared clinical phenotypes observed at multiple clinic sites and used as a springboard for future clinical and basic research studies.

This study investigated the phenotypic manifestations of interstitial duplications of chromosome 15 that involve the Prader-Willi/Angelman syndrome critical region (PWACR). Twenty-one affected individuals from six families were evaluated in detail, using standardized and semi-standardized measures of intelligence, psychopathology, and physical anomalies. Special attention was placed on determining the prevalence of autism spectrum disorders as well as the relationship between the parental origin of the duplication and the phenotypic effects. Assessments of the affected individuals were compared with evaluations of the unaffected relatives from the same families. Results indicated that duplications in the region were associated with variable degrees of intellectual impairments and motor coordination problems. Four of the subjects received a diagnosis of pervasive developmental disorder. Three of these cases were probands and only one met criteria for classic autism. There was very little evidence of the duplication cosegregating with autism spectrum disorder diagnosis. Paternally inherited duplications were significantly less likely to give rise to phenotypic effects. The findings indicate that duplications in the PWACR give rise to developmental delay but not necessarily autism spectrum disorders. They also suggest that phenotypic expression is dependent on the parental origin of the duplication and implicate maternally active genes in the pathogenesis of the developmental impairments. Further research will be required to clarify the range and basis of the phenotypic manifestations.

Background Duplications of 15q11.2-q13.1 (Dup15q syndrome) are highly penetrant for autism spectrum disorder (ASD). A distinct electrophysiological (EEG) pattern characterized by excessive activity in the beta band has been noted in clinical reports. We asked whether EEG power in the beta band, as well as in other frequency bands, distinguished children with Dup15q syndrome from those with non-syndromic ASD and then examined the clinical correlates of this electrophysiological biomarker in Dup15q syndrome. Methods In the first study, we recorded spontaneous EEG from children with Dup15q syndrome (n = 11), age-and-IQ-matched children with ASD (n = 10) and age-matched typically developing (TD) children (n = 9) and computed relative power in 6 frequency bands for 9 regions of interest (ROIs). Group comparisons were made using a repeated measures analysis of variance. In the second study, we recorded spontaneous EEG from a larger cohort of individuals with Dup15q syndrome (n = 27) across two sites and examined age, epilepsy, and duplication type as predictors of beta power using simple linear regressions. Results In the first study, spontaneous beta1 (12–20 Hz) and beta2 (20–30 Hz) power were significantly higher in Dup15q syndrome compared with both comparison groups, while delta (1–4 Hz) was significantly lower than both comparison groups. Effect sizes in all three frequency bands were large (|d| > 1). In the second study, we found that beta2 power was significantly related to epilepsy diagnosis in Dup15q syndrome. Conclusions Here, we have identified an electrophysiological biomarker of Dup15q syndrome that may facilitate clinical stratification, treatment monitoring, and measurement of target engagement for future clinical trials. Future work will investigate the genetic and neural underpinnings of this electrophysiological signature as well as the functional consequences of excessive beta oscillations in Dup15q syndrome.

SummaryObjective Seizures are common in individuals with duplications of chromosome 15q11.2-q13 (Dup15q). The goal of this study was to examine the phenotypes and treatments of seizures in Dup15q in a large population. Methods A detailed electronic survey was conducted through the Dup15q Alliance containing comprehensive questions regarding seizures and their treatments in Dup15q. Results There were 95 responses from Dup15q families. For the 83 with idic(15), 63% were reported to have seizures, of which 81% had multiple seizure types and 42% had infantile spasms. Other common seizure types were tonic–clonic, atonic, myoclonic, and focal. Only 3 of 12 individuals with int dup(15) had seizures. Broad spectrum antiepileptic drugs (AEDs) were the most effective medications, but carbamazepine and oxcarbazepine were also effective, although typical benzodiazepines were relatively ineffective. There was a 24% response rate (>90% seizure reduction) to the first AED tried. For those with infantile spasms, adrenocorticotropic hormone (ACTH) was more effective than vigabatrin. Significance This is the largest study assessing seizures in Duplication 15q syndrome, but because this was a questionnaire-based study with a low return rate, it is susceptible to bias. Seizures are common in idic(15) and typically difficult to control, often presenting with infantile spasms and progressing to a Lennox-Gastaut–type syndrome. Seizures in those with int dup(15) are less common, with a frequency similar to the general autism population. In addition to broad spectrum AED, medications such as carbamazepine and oxcarbazepine are also relatively effective in controlling seizures in this population, suggesting a possible multifocal etiology, which may also explain the high rate of infantile spasms. Our small sample suggests a relative lack of efficacy of vigabatrin and other γ-aminobutyric acid (GABA)ergic medications, such as typical benzodiazepines, which may be attributable to abnormal GABAergic transmission resulting from the duplication of a cluster of GABAβ3 receptor genes in the 15q11.2-13 region.

Background 15q11-q13 region is an area of well-known susceptibility to genomic rearrangements, in which several breakpoints have been identified (BP1–BP5). Duplication of this region is observed in two instances: presence of a supernumerary marker chromosome (SMC) derived of chromosome 15, or interstitial tandem duplication. Duplications are clinically characterized by a variable phenotype that includes central hypotonia, developmental delay, speech delay, seizure, minor dysmorphic features and autism. Methods Retrospective clinical and molecular study of 30 unrelated patients who were identified among the patients seen at the genetic clinics of Robert DEBRE hospital with microduplication of the 15q11-q13 region. Results Fifteen patients presented with a supernumerary marker derived from chromosome 15. In fourteen cases the SMC was of large size, encompassing the Prader–Willi/Angelman critical region. All but one was maternal in origin. One patient had a PWS-like phenotype in absence of maternal UPD. In one case, the marker had a smaller size and contained only the BP1–BP2 region. Fifteen patients presented with interstitial duplication. Four cases were inherited from phenotypically normal parents (3 maternal and 1 paternal). Phenotypic features were somewhat variable and 57% presented with autism. Twelve patients showed cerebral anomalies and 18 patients had an abnormal EEG with a typical, recognizable pattern of excessive diffuse rapid spikes in the waking record, similar to the pattern observed after benzodiazepine exposure. Duplication of paternally expressed genes MKRN3 , MAGEL2 and NDN in two autistic patients without extra material of a neighboring region enhances their likelihood to be genes related to autism.

International audience; BACKGROUND: Maternally derived duplications of the 15q11-q13 region are the most frequently reported chromosomal aberrations in autism spectrum disorders (ASD). Prader-Willi and Angelman syndromes, caused by 15q11-q13 deletions or abnormal methylation of imprinted genes, are also associated with ASD. However, the prevalence of these disorders in ASD is unknown. The aim of this study was to assess the frequency of 15q11-q13 rearrangements in a large sample of patients ascertained for ASD. METHODS: A total of 522 patients belonging to 430 families were screened for deletions, duplications, and methylation abnormalities involving 15q11-q13 with multiplex ligation-dependent probe amplification (MLPA). RESULTS: We identified four patients with 15q11-q13 abnormalities: a supernumerary chromosome 15, a paternal interstitial duplication, and two subjects with Angelman syndrome, one with a maternal deletion and the other with a paternal uniparental disomy. CONCLUSIONS: Our results show that abnormalities of the 15q11-q13 region are a significant cause of ASD, accounting for approximately 1% of cases. Maternal interstitial 15q11-q13 duplications, previously reported to be present in 1% of patients with ASD, were not detected in our sample. Although paternal duplications of chromosome 15 remain phenotypically silent in the majority of patients, they can give rise to developmental delay and ASD in some subjects, suggesting that paternally expressed genes in this region can contribute to ASD, albeit with reduced penetrance compared with maternal duplications. These findings indicate that patients with ASD should be routinely screened for 15q genomic imbalances and methylation abnormalities and that MLPA is a reliable, rapid, and cost-effective method to perform this screening.

The inv dup(15) or idic(15) syndrome displays distinctive clinical findings represented by early central hypotonia, developmental delay and intellectual disability, epilepsy, and autistic behaviour. Incidence at birth is estimated at 1 in 30,000 with a sex ratio of almost 1:1. Developmental delay and intellectual disability affect all individuals with inv dup(15) and are usually moderate to profound. Expressive language is absent or very poor and often echolalic. Comprehension is very limited and contextual. Intention to communicate is absent or very limited. The distinct behavioral disorder shown by children and adolescents has been widely described as autistic or autistic-like. Epilepsy with a wide variety of seizure types can occur in these individuals, with onset between 6 months and 9 years. Various EEG abnormalities have been described. Muscle hypotonia is observed in almost all individuals, associated, in most of them, with joint hyperextensibility and drooling. Facial dysmorphic features are absent or subtle, and major malformations are rare. Feeding difficulties are reported in the newborn period. Chromosome region 15q11q13, known for its instability, is highly susceptible to clinically relevant genomic rearrangements, such as supernumerary marker chromosomes formed by the inverted duplication of proximal chromosome 15. Inv dup(15) results in tetrasomy 15p and partial tetrasomy 15q. The large rearrangements, containing the Prader-Willi/Angelman syndrome critical region (PWS/ASCR), are responsible for the inv dup(15) or idic(15) syndrome. Diagnosis is achieved by standard cytogenetics and FISH analysis, using probes both from proximal chromosome 15 and from the PWS/ASCR. Microsatellite analysis on parental DNA or methylation analysis on the proband DNA, are also needed to detect the parent-of-origin of the inv dup(15) chromosome. Array CGH has been shown to provide a powerful approach for identifying and detecting the extent of the duplication. The possible occurrence of double supernumerary isodicentric chromosomes derived from chromosome 15, resulting in partial hexasomy of the maternally inherited PWS/ASCR, should be considered in the differential diagnosis. Large idic(15) are nearly always sporadic. Antenatal diagnosis is possible. Management of inv dup(15) includes a comprehensive neurophysiologic and developmental evaluation. Survival is not significantly reduced. Disease name and synonyms The inv dup(15) or idic(15) syndrome can also be termed "tetrasomy 15q". About 160 patients have been reported in the medical literature 12345.

A cluster of low copy repeats on the proximal long arm of chromosome 15 mediates various forms of stereotyped deletions and duplication events that cause a group of neurodevelopmental disorders that are associated with autism or autism spectrum disorders (ASD). The region is subject to genomic imprinting and the behavioral phenotypes associated with the chromosome 15q11.2-q13 disorders show a parent-of-origin specific effect that suggests that an increased copy number of maternally derived alleles contributes to autism susceptibility. Notably, nonimprinted, biallelically expressed genes within the interval also have been shown to be misexpressed in brains of patients with chromosome 15q11.2-q13 genomic disorders, indicating that they also likely play a role in the phenotypic outcome. This review provides an overview of the phenotypes of these disorders and their relationships with ASD and outlines the regional genes that may contribute to the autism susceptibility imparted by copy number variation of the region.

The most common of the heterogeneous group of the extra structurally abnormal chromosomes (ESACs) is the inv dup(15), whose presence results in tetrasomy 15p and partial tetrasomy 15q. Inv dup(15), containing the Prader-Willi/Angelman syndrome (PWS/AS) region, are constantly associated with phenotypic abnormalities and mental retardation. We report on four additional patients with inv dup(15), whose behavioral pattern, and neurologic and physical findings further delineate the phenotype of this neurogenetic syndrome. We also provide FISH analyses on chromosomes of the observed ESACs and discuss the role of a number of genes located within the tetrasomic region.

Background Duplication of chromosome 15q11-q13 (dup15q) accounts for approximately 3% of autism cases. Chromosome 15q11-q13 contains imprinted genes necessary for normal mammalian neurodevelopment controlled by a differentially methylated imprinting center (imprinting center of the Prader-Willi locus, PWS-IC). Maternal dup15q occurs as both interstitial duplications and isodicentric chromosome 15. Overexpression of the maternally expressed gene UBE3A is predicted to be the primary cause of the autistic features associated with dup15q. Previous analysis of two postmortem dup15q frontal cortical samples showed heterogeneity between the two cases, with one showing levels of the GABAA receptor genes, UBE3A and SNRPN in a manner not predicted by copy number or parental imprint. Methods Postmortem human brain tissue (Brodmann area 19, extrastriate visual cortex) was obtained from 8 dup15q, 10 idiopathic autism and 21 typical control tissue samples. Quantitative PCR was used to confirm duplication status. Quantitative RT-PCR and Western blot analyses were performed to measure 15q11-q13 transcript and protein levels, respectively. Methylation-sensitive high-resolution melting-curve analysis was performed on brain genomic DNA to identify the maternal:paternal ratio of methylation at PWS-IC. Results Dup15q brain samples showed a higher level of PWS-IC methylation than control or autism samples, indicating that dup15q was maternal in origin. UBE3A transcript and protein levels were significantly higher than control and autism in dup15q, as expected, although levels were variable and lower than expected based on copy number in some samples. In contrast, this increase in copy number did not result in consistently increased GABRB3 transcript or protein levels for dup15q samples. Furthermore, SNRPN was expected to be unchanged in expression in dup15q because it is expressed from the single unmethylated paternal allele, yet SNRPN levels were significantly reduced in dup15q samples compared to controls. PWS-IC methylation positively correlated with UBE3A and GABRB3 levels but negatively correlated with SNRPN levels. Idiopathic autism samples exhibited significantly lower GABRB3 and significantly more variable SNRPN levels compared to controls. Conclusions Although these results show that increased UBE3A/UBE3A is a consistent feature of dup15q syndrome, they also suggest that gene expression within 15q11-q13 is not based entirely on copy number but can be influenced by epigenetic mechanisms in brain.

Background Duplications of the chromosome 15q11-q13.1 region are associated with an estimated 1 to 3% of all autism cases, making this copy number variation (CNV) one of the most frequent chromosome abnormalities associated with autism spectrum disorder (ASD). Several genes located within the 15q11-q13.1 duplication region including ubiquitin protein ligase E3A (UBE3A), the gene disrupted in Angelman syndrome (AS), are involved in neural function and may play important roles in the neurobehavioral phenotypes associated with chromosome 15q11-q13.1 duplication (Dup15q) syndrome. Methods We have generated induced pluripotent stem cell (iPSC) lines from five different individuals containing CNVs of 15q11-q13.1. The iPSC lines were differentiated into mature, functional neurons. Gene expression across the 15q11-q13.1 locus was compared among the five iPSC lines and corresponding iPSC-derived neurons using quantitative reverse transcription PCR (qRT-PCR). Genome-wide gene expression was compared between neurons derived from three iPSC lines using mRNA-Seq. Results Analysis of 15q11-q13.1 gene expression in neurons derived from Dup15q iPSCs reveals that gene copy number does not consistently predict expression levels in cells with interstitial duplications of 15q11-q13.1. mRNA-Seq experiments show that there is substantial overlap in the genes differentially expressed between 15q11-q13.1 deletion and duplication neurons, Finally, we demonstrate that UBE3A transcripts can be pharmacologically rescued to normal levels in iPSC-derived neurons with a 15q11-q13.1 duplication. Conclusions Chromatin structure may influence gene expression across the 15q11-q13.1 region in neurons. Genome-wide analyses suggest that common neuronal pathways may be disrupted in both the Angelman and Dup15q syndromes. These data demonstrate that our disease-specific stem cell models provide a new tool to decipher the underlying cellular and genetic disease mechanisms of ASD and may also offer a pathway to novel therapeutic intervention in Dup15q syndrome.