Angelman Syndrome

Mendelian MONDO:0007113 Pathograph 38 Neurodevelopmental disorder Imprinting disorder

Angelman syndrome is a neurogenetic imprinting disorder caused by deficient neuronal expression of the maternally inherited UBE3A allele, with severe developmental impairment, minimal speech, gait ataxia, seizures, and a characteristic behavioral phenotype.

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Classifications

Harrison's Chapter

🔗

Mappings

MONDO

MONDO:0007113 Angelman syndrome

Orphanet lists MONDO:0007113 as an exact cross-reference for Angelman syndrome.

ICD-10-CM

ICD10CM:Q93.5 Other deletions of part of a chromosome

Orphanet lists ICD-10 Q93.5 as a narrower cross-reference for Angelman syndrome.

📘

Definitions

Clinical syndrome definition

Angelman syndrome is defined clinically by severe developmental delay or intellectual disability, severe speech impairment, ataxic movement disorder, characteristic happy demeanor, and frequent co-occurrence of seizures and microcephaly.

CASE_DEFINITION Core clinical phenotype in pediatric and adult practice

Show evidence (2 references)

PMID:20301323 SUPPORT Human Clinical

"Angelman syndrome (AS) is characterized by severe developmental delay or intellectual disability, severe speech impairment, gait ataxia and/or tremulousness of the limbs, and unique behavior with an apparent happy demeanor that includes frequent laughing, smiling, and excitability."

Defines the canonical clinical syndrome.

PMID:20301323 SUPPORT Human Clinical

"Microcephaly and seizures are also common."

Adds core neurologic features used in clinical recognition.

Orphanet disease definition

Orphanet defines Angelman syndrome as a rare genetic neurodevelopmental disorder characterized by moderate to severe intellectual disability, microcephaly, seizures, ataxic gait and distinct abnormal facial shape.

CASE_DEFINITION

Show evidence (1 reference)

ORPHA:72 SUPPORT Other

"A rare genetic neurodevelopmental disorder characterized by moderate to severe intellectual disability, microcephaly, seizures, ataxic gait and distinct abnormal facial shape."

Orphanet's definition supports the neurodevelopmental disorder framing of this entry.

Molecular diagnostic criteria framework

Molecular diagnosis is primarily established by 15q11.2-q13 methylation testing with reflex UBE3A sequence analysis when methylation testing is negative.

DIAGNOSTIC_CRITERIA Molecular confirmation strategy for suspected Angelman syndrome

Show evidence (2 references)

PMID:20301323 SUPPORT Human Clinical

"Analysis of parent-specific DNA methylation imprints in the 15q11.2-q13 chromosome region detects approximately 80% of individuals with AS, including those with a deletion, uniparental disomy, or an imprinting defect; fewer than 1% of individuals have a cytogenetically visible chromosome..."

Supports methylation analysis as first-line molecular testing.

PMID:20301323 SUPPORT Human Clinical

"UBE3A sequence analysis detects pathogenic variants in an additional approximately 11% of individuals."

Supports second-tier sequencing for methylation-negative cases.

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Inheritance

Autosomal dominant inheritance with maternal imprinting HP:0012275

Disease expression requires loss of the maternally inherited functional UBE3A allele in neurons; most cases are simplex/de novo.

Autosomal dominant inheritance with maternal imprinting Penetrance: COMPLETE

Show evidence (2 references)

PMID:20301323 SUPPORT Human Clinical

"Individuals with AS typically represent simplex cases (i.e., a single affected family member) and have the disorder as the result of a de novo genetic alteration associated with a very low recurrence risk."

Supports predominant de novo occurrence in clinical practice.

PMID:20301323 SUPPORT Human Clinical

"Less commonly, an individual with AS has the disorder as the result of a genetic alteration associated with an imprinting pattern of autosomal dominant inheritance or variable recurrence risk."

Supports the imprinting-associated autosomal dominant inheritance mechanism.

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Subtypes

Maternal 15q11.2-q13 deletion Angelman syndrome

70%

Most common molecular subtype, caused by de novo deletion of the maternally inherited 15q11.2-q13 region including UBE3A. The deletion frequently spans the GABRB3-GABRA5-GABRG3 GABA-A receptor subunit cluster and OCA2, contributing to a more severe and earlier-onset epilepsy phenotype and to oculocutaneous hypopigmentation features distinguishing this subtype.

Show evidence (5 references)

PMID:14510623 SUPPORT Human Clinical

"Approximately 70% of patients show a deletion involving the maternally inherited chromosome 15q11-q13, encompassing a cluster of gamma-aminobutyric acid receptor subunit genes"

Quantifies and defines the major deletion subtype.

PMID:34536900 SUPPORT Human Clinical

"Epilepsy was reported in a greater proportion of individuals with a deletion than a nondeletion genotype"

Quantifies the higher epilepsy burden in deletion-genotype Angelman syndrome.

PMID:34536900 SUPPORT Human Clinical

"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."

Establishes earlier seizure onset and more severe epilepsy phenotype in deletion-genotype AS.

+ 2 more references

UBE3A pathogenic variant Angelman syndrome

6-11% UBE3A hgnc:12496

Subtype caused by pathogenic variants in maternally inherited UBE3A.

Show evidence (2 references)

PMID:14510623 SUPPORT Human Clinical

"6% harbor intragenic mutations of the ubiquitin-protein ligase E3A (UBE3A) gene."

Supports a distinct UBE3A-variant molecular subtype.

PMID:20301323 SUPPORT Human Clinical

"UBE3A sequence analysis detects pathogenic variants in an additional approximately 11% of individuals."

Provides an additional estimate from a contemporary GeneReviews summary.

Paternal uniparental disomy 15 Angelman syndrome

Subtype caused by paternal uniparental disomy of chromosome 15 with absent functional maternal UBE3A contribution in neurons.

Show evidence (1 reference)

PMID:14510623 SUPPORT Human Clinical

"3% show chromosome 15 paternal uniparental disomy (UPD)"

Supports UPD as a recognized molecular subtype.

Imprinting defect Angelman syndrome

Subtype caused by imprinting center defects disrupting maternal-expression pattern at the 15q11.2-q13 locus.

Show evidence (1 reference)

PMID:14510623 SUPPORT Human Clinical

"1% harbor a mutation in the imprinting center (a transcriptional regulatory element)"

Supports imprinting-center defects as a rarer molecular subtype.

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Pathophysiology

Maternal UBE3A allele disruption

Angelman syndrome is initiated by disruption of the maternally inherited UBE3A allele (deletion, pathogenic variant, UPD context, or imprinting defect).

neuron CL:0000540

UBE3A hgnc:12496

nervous system UBERON:0001016

Downstream

Neuron-specific paternal UBE3A silencing Neuronal imprinting limits compensatory expression from the paternal allele.

Show evidence (1 reference)

PMID:33543479 SUPPORT Other

"Angelman syndrome is caused by mutations affecting the maternally inherited UBE3A gene, which encodes an E3-ubiquitin ligase that is critical for typical postnatal brain development."

Establishes the initiating molecular lesion.

Neuron-specific paternal UBE3A silencing

In neurons, the paternal UBE3A allele is silenced by imprinting, so maternal disruption leads to loss of effective neuronal UBE3A expression.

neuron CL:0000540

UBE3A hgnc:12496

nervous system UBERON:0001016

Downstream

Reduced neuronal UBE3A protein abundance Effective neuronal UBE3A protein dosage falls below physiologic levels.

Show evidence (1 reference)

PMID:33543479 SUPPORT Other

"in neurons only the maternally inherited UBE3A gene is expressed."

Supports neuron-specific imprinting mechanism.

Reduced neuronal UBE3A protein abundance

Loss of UBE3A protein in neurons reduces E3-ligase-dependent control of protein turnover signaling.

neuron CL:0000540

brain UBERON:0000955

Downstream

Decreased UBE3A-mediated protein ubiquitination Lower UBE3A dosage reduces normal ubiquitination activity in neuronal systems.

Show evidence (2 references)

PMID:33543479 SUPPORT Other

"Angelman syndrome is caused by the loss of UBE3A protein."

Supports this discrete protein-abundance event.

PMID:40671377 SUPPORT In Vitro

"AS arises due to the neuronal loss of UBE3A, an E3 ligase that regulates protein abundance through the addition of lysine 48 (K48)-linked polyubiquitin chains to proteins targeted for degradation by the ubiquitin proteasome system (UPS)."

Human iPSC-derived cortical-neuron study provides direct molecular support linking neuronal UBE3A loss to altered ubiquitin-dependent protein regulation.

Decreased UBE3A-mediated protein ubiquitination

UBE3A-dependent ubiquitination signaling is reduced, with downstream dysregulation of protein-stability control.

neuron CL:0000540

protein ubiquitination GO:0016567 ↓ DECREASED regulation of protein stability GO:0031647 ↕ DYSREGULATED

brain UBERON:0000955

Downstream

Dysregulated neuronal signaling pathways Loss of ubiquitination control contributes to broad pathway-level signaling derangement.

Show evidence (2 references)

PMID:33543479 SUPPORT Other

"Loss of UBE3A affects multiple signalling pathways in the brain."

Supports broad neuronal signaling dysregulation downstream of reduced ubiquitination control.

PMID:40671377 SUPPORT In Vitro

"We provide evidence UBE3A polyubiquitinates PACSIN1 and GRIPAP1 to regulate protein turnover, with potential implications for impaired activity-dependent synaptic plasticity observed in AS."

Adds direct mechanistic evidence that UBE3A-dependent ubiquitination regulates neuronal protein turnover linked to synaptic dysfunction.

Dysregulated neuronal signaling pathways

Multiple brain signaling pathways become dysregulated rather than a single isolated pathway defect.

neuron CL:0000540

brain UBERON:0000955

Downstream

Impaired experience-dependent synaptic remodeling Broad pathway dysregulation contributes to synaptic plasticity and remodeling defects.

Show evidence (1 reference)

PMID:33543479 SUPPORT Other

"given the multitude of signalling mechanisms that are derailed, it is unlikely that targeting a single pathway is going to be very effective."

Supports multipathway dysregulation framing.

Impaired experience-dependent synaptic remodeling

UBE3A-related network pathology impairs synaptic organization and remodeling in neuronal circuits.

neuron CL:0000540

synapse organization GO:0050808 ↕ DYSREGULATED

cerebral cortex UBERON:0000956

Downstream

Disrupted neuronal excitability homeostasis Synaptic remodeling defects alter network excitability and transmission balance.

Severe intellectual disability Synaptic remodeling dysfunction contributes to severe cognitive impairment.

Severe speech impairment Synaptic-network disruption contributes to profound expressive language deficits.

Gait ataxia Network-level motor-circuit dysfunction contributes to persistent gait ataxia.

Global developmental delay Synaptic remodeling failure across cortical circuits manifests as universal early developmental delay.

Microcephaly UBE3A-dependent neuronal/synaptic developmental defects contribute to acquired postnatal microcephaly.

Tremor Synaptic remodeling defects in motor circuits produce limb tremulousness.

Hyperactivity Cortical and limbic synaptic-circuit dysfunction contributes to hypermotoric/hyperactive behavior.

Inappropriate laughter Disrupted limbic-cortical synaptic networks contribute to the characteristic happy demeanor and unprovoked laughter.

Scoliosis Hypotonia and motor-circuit dysfunction secondary to synaptic remodeling defects predispose to progressive spinal curvature.

Show evidence (3 references)

PMID:24876791 SUPPORT Model Organism

"Studies of mouse models of AS have implicated UBE3A in experience-dependent synaptic remodeling."

Supports this discrete synaptic-remodeling event.

PMID:36237484 SUPPORT Model Organism

"Like in male AS mice, long-term potentiation (LTP) was significantly reduced while long-term depression (LTD) was enhanced at hippocampal CA3-CA1 synapses of female AS mice, as compared to female WT mice."

Provides synapse-level electrophysiologic evidence for impaired plasticity in Angelman model systems.

PMID:40310720 SUPPORT Model Organism

"Moreover, deficits in mEPSC frequency and spike-timing-dependent long-term potentiation, as well as certain behaviors including cognitive inflexibility found in AS mice, are rescued when bred with Kv4.2 conditional knockout mice."

Supports causal linkage between UBE3A downstream signaling defects and synaptic plasticity abnormalities.

Disrupted neuronal excitability homeostasis

Neuronal excitatory/inhibitory balance and electrophysiologic homeostasis are disrupted in cortical networks.

neuron CL:0000540

modulation of chemical synaptic transmission GO:0050804 ↕ DYSREGULATED regulation of membrane potential GO:0042391 ↕ DYSREGULATED

cerebral cortex UBERON:0000956

Downstream

Cortical network hyperexcitability with abnormal EEG background Physiologic instability at synaptic and membrane levels manifests as hyperexcitable cortical activity.

Show evidence (2 references)

PMID:33543479 SUPPORT Other

"It has been consistently shown that mouse models of Angelman syndrome show marked changes in synaptic plasticity and excitatory/inhibitory balance."

Supports disrupted excitability homeostasis event.

PMID:39914145 SUPPORT Model Organism

"The axon initial segment (AIS) is a critical regulator of neuronal excitability and the initiation site of action potentials."

Adds direct mechanistic support for excitability-homeostasis framing in cortical neurons.

GABA-A receptor cluster hemizygosity in deletion subtype

In deletion-type Angelman syndrome, hemizygous loss of the contiguous GABRB3-GABRA5-GABRG3 GABA-A receptor subunit cluster compounds neuronal UBE3A loss and contributes to a more severe epilepsy and EEG phenotype than in non-deletion genotypes.

neuron CL:0000540

GABRB3 hgnc:4083 GABRA5 hgnc:4079 GABRG3 hgnc:4088

cerebral cortex UBERON:0000956

Downstream

Cortical network hyperexcitability with abnormal EEG background GABA-A receptor cluster hemizygosity exacerbates excitatory/inhibitory imbalance and epileptiform network activity.

Show evidence (2 references)

PMID:30826071 SUPPORT Human Clinical

"Angelman syndrome (AS) is a severe neurodevelopmental disorder caused by either disruptions of the gene UBE3A or deletion of chromosome 15 at 15q11-q13, which encompasses UBE3A and several other genes, including GABRB3, GABRA5, GABRG3, encoding gamma-aminobutyric acid type A receptor subunits..."

Establishes the contiguous gene context of deletion AS.

PMID:34536900 SUPPORT Human Clinical

Supports clinically more severe epilepsy phenotype in deletion AS attributable to contiguous gene effects.

OCA2 haploinsufficiency in deletion subtype

Codeletion of OCA2 in the typical 15q11.2-q13 deletion produces partial oculocutaneous albinism features (iris hypopigmentation, severe astigmatism, and high myopia) restricted to the deletion subtype.

melanocyte CL:0000148

OCA2 hgnc:8101

eye UBERON:0000970

Downstream

Iris hypopigmentation OCA2 haploinsufficiency reduces ocular pigmentation in deletion-type AS.

Astigmatism Reduced melanin during ocular development contributes to refractive abnormality, with high astigmatism enriched in the deletion subgroup.

Myopia OCA2 haploinsufficiency contributes to high myopia restricted to deletion-type AS.

Show evidence (1 reference)

PMID:41905512 SUPPORT Human Clinical

"The 15q11.2-q13 deletions confer a distinct oculoalbinism phenotype mediated by OCA2 haploinsufficiency, featuring high myopia, severe astigmatism, and iris hypopigmentation."

Defines OCA2 codeletion as the molecular driver of the deletion-specific ophthalmic phenotype.

Cortical network hyperexcitability with abnormal EEG background

Hyperexcitable cortical networks produce persistent epileptiform liability and abnormal electroencephalographic backgrounds.

neuron CL:0000540

cerebral cortex UBERON:0000956

Downstream

Seizures Hyperexcitable cortical networks drive recurrent seizure phenotypes.

Sleep disturbance Persistent network instability contributes to long-term sleep dysregulation.

Show evidence (3 references)

PMID:14510623 SUPPORT Human Clinical

"Seizures, abnormal electroencephalography, microcephaly, and scoliosis are observed in >80% of patients."

Supports coupling of epileptic burden with abnormal EEG background.

PMID:29719672 SUPPORT Human Clinical

"Individuals with AS display characteristic EEG patterns including high-amplitude rhythmic delta waves."

Provides quantitative-EEG description of the abnormal cortical-network background.

PMID:35611307 SUPPORT Human Clinical

"Delta power measured in the scalp EEG is a reliable biomarker for Angelman syndrome but varies widely across individuals and throughout development, making detection of a treatment effect using single measurements challenging."

Establishes elevated EEG delta as a translatable biomarker of cortical network hyperexcitability.

Autonomic and enteric nervous system dysfunction

UBE3A loss in autonomic and enteric neuronal populations contributes to pervasive gastrointestinal dysmotility manifesting as constipation and gastroesophageal reflux across the AS lifespan.

neuron CL:0000540

peristalsis GO:0030432 ↓ DECREASED

enteric nervous system UBERON:0002005

Downstream

Constipation Enteric/autonomic dysfunction contributes to chronic constipation in AS.

Gastroesophageal reflux Enteric/autonomic dysfunction with impaired esophageal motility contributes to GERD.

Show evidence (1 reference)

PMID:28816003 SUPPORT Human Clinical

"The majority of patients' medical records indicated at least one symptom of gastrointestinal dysfunction, with constipation and gastroesophageal reflux disease (GERD) the most common."

Establishes the high prevalence of GI dysmotility consistent with autonomic/enteric nervous system involvement in AS.

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Pathograph

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Phenotypes

Digestive 3

Constipation VERY_FREQUENT Constipation HP:0002019

Show evidence (1 reference)

PMID:28816003 SUPPORT Human Clinical

"The majority of patients' medical records indicated at least one symptom of gastrointestinal dysfunction, with constipation and gastroesophageal reflux disease (GERD) the most common."

Supports constipation as one of the most prevalent GI comorbidities.

Gastroesophageal reflux FREQUENT Gastroesophageal reflux HP:0002020

Show evidence (1 reference)

PMID:28816003 SUPPORT Human Clinical

"The majority of patients' medical records indicated at least one symptom of gastrointestinal dysfunction, with constipation and gastroesophageal reflux disease (GERD) the most common."

Supports GERD as a major GI phenotype in AS.

Feeding difficulties FREQUENT Feeding difficulties HP:0011968

Show evidence (1 reference)

ORPHA:72 SUPPORT Other

"HP:0011968 | Feeding difficulties | Frequent (79-30%)"

Orphanet phenotype table rates feeding difficulties as frequent (79-30%).

Eye 2

Strabismus FREQUENT Strabismus HP:0000486

Show evidence (2 references)

PMID:41905512 SUPPORT Human Clinical

"Ophthalmic manifestations in Angelman syndrome (AS)-particularly strabismus surgical outcomes and genotype-phenotype correlations-remain inadequately characterized due to limited cohort sizes in prior studies."

Documents strabismus as a clinically significant ophthalmic manifestation requiring surgical correction in AS.

ORPHA:72 SUPPORT Other

"HP:0000486 | Strabismus | Frequent (79-30%)"

Orphanet phenotype table confirms frequent (79-30%) strabismus.

Myopia Myopia HP:0000545

Show evidence (1 reference)

PMID:41905512 SUPPORT Human Clinical

"High myopia (> -6.00 D) occurred exclusively in deletion patients (n = 2)."

Documents the deletion-restricted high-myopia phenotype.

Head and Neck 3

Microcephaly VERY_FREQUENT Microcephaly HP:0000252

Show evidence (2 references)

PMID:14510623 SUPPORT Human Clinical

"Seizures, abnormal electroencephalography, microcephaly, and scoliosis are observed in >80% of patients."

Supports very high prevalence of microcephaly.

ORPHA:72 SUPPORT Other

"HP:0000252 | Microcephaly | Very frequent (99-80%)"

Orphanet phenotype table confirms very frequent (99-80%) microcephaly.

Drooling FREQUENT Drooling HP:0002307

Show evidence (1 reference)

ORPHA:72 SUPPORT Other

"HP:0002307 | Drooling | Frequent (79-30%)"

Orphanet phenotype table rates drooling as frequent (79-30%).

Wide mouth FREQUENT Wide mouth HP:0000154

Show evidence (1 reference)

ORPHA:72 SUPPORT Other

"HP:0000154 | Wide mouth | Frequent (79-30%)"

Orphanet phenotype table rates wide mouth as frequent (79-30%).

Integument 2

Hypopigmentation of the skin FREQUENT Hypopigmentation of the skin HP:0001010

Show evidence (1 reference)

ORPHA:72 SUPPORT Other

"HP:0001010 | Hypopigmentation of the skin | Frequent (79-30%)"

Orphanet phenotype table rates skin hypopigmentation as frequent (79-30%).

Fair hair FREQUENT Fair hair HP:0002286

Show evidence (1 reference)

ORPHA:72 SUPPORT Other

"HP:0002286 | Fair hair | Frequent (79-30%)"

Orphanet phenotype table rates fair hair as frequent (79-30%).

Musculoskeletal 2

Scoliosis FREQUENT Scoliosis HP:0002650

Show evidence (2 references)

PMID:14510623 SUPPORT Human Clinical

"Seizures, abnormal electroencephalography, microcephaly, and scoliosis are observed in >80% of patients."

Supports scoliosis as a common and clinically relevant musculoskeletal manifestation.

ORPHA:72 SUPPORT Other

"HP:0002650 | Scoliosis | Frequent (79-30%)"

Orphanet phenotype table rates scoliosis as frequent (79-30%).

Infantile hypotonia FREQUENT Floppy infant HP:0008947

Show evidence (1 reference)

ORPHA:72 SUPPORT Other

"HP:0008947 | Floppy infant | Frequent (79-30%)"

Orphanet phenotype table rates infantile hypotonia as frequent (79-30%).

Nervous System 15

Severe intellectual disability VERY_FREQUENT Severe intellectual disability HP:0010864

Show evidence (2 references)

PMID:20301323 SUPPORT Human Clinical

"Angelman syndrome (AS) is characterized by severe developmental delay or intellectual disability"

Supports severe cognitive impairment as a core phenotype.

ORPHA:72 SUPPORT Other

"HP:0010864 | Intellectual disability, severe | Very frequent (99-80%)"

Orphanet phenotype table confirms very frequent (99-80%) severe intellectual disability.

Global developmental delay VERY_FREQUENT Global developmental delay HP:0001263

Show evidence (1 reference)

PMID:14510623 SUPPORT Human Clinical

"Clinical findings present in all patients include developmental delay, which becomes apparent by 6-12 months of age"

Supports near-universal developmental delay and its timing.

Severe speech impairment VERY_FREQUENT Poor speech HP:0002465

Show evidence (1 reference)

PMID:14510623 SUPPORT Human Clinical

"Clinical findings present in all patients include developmental delay, which becomes apparent by 6-12 months of age, severely impaired expressive language"

Supports severe expressive language impairment as a defining feature.

Gait ataxia VERY_FREQUENT Gait ataxia HP:0002066

Show evidence (2 references)

ORPHA:72 SUPPORT Other

"HP:0001251 | Ataxia | Very frequent (99-80%)"

Orphanet phenotype table confirms very frequent (99-80%) ataxia; gait ataxia is a child term.

PMID:20301323 SUPPORT Human Clinical

"Angelman syndrome (AS) is characterized by severe developmental delay or intellectual disability, severe speech impairment, gait ataxia and/or tremulousness of the limbs"

Supports ataxic gait as a cardinal motor phenotype.

Seizures VERY_FREQUENT Seizure HP:0001250

Show evidence (2 references)

PMID:20398390 SUPPORT Human Clinical

"Epilepsy, often severe and hard to control, is present in 85% of patients within the first three years of life, although less than 25% develop seizures during the first year."

Quantifies high seizure prevalence and early onset.

ORPHA:72 SUPPORT Other

"HP:0001250 | Seizure | Very frequent (99-80%)"

Orphanet phenotype table confirms very frequent (99-80%) seizures.

Sleep disturbance FREQUENT Sleep disturbance HP:0002360

Show evidence (1 reference)

PMID:24876791 SUPPORT Human Clinical

"The behavioral features of AS include a happy demeanor, easily provoked laughter, short attention span, hypermotoric behavior, mouthing of objects, sleep disturbance, and an affinity for water."

Supports sleep disturbance as a recurring syndrome feature.

Hyperactivity VERY_FREQUENT Hyperactivity HP:0000752

Show evidence (1 reference)

PMID:14510623 SUPPORT Human Clinical

"Clinical findings present in all patients include developmental delay, which becomes apparent by 6-12 months of age, severely impaired expressive language, ataxic gait, tremulousness of limbs, and a typical behavioral profile, including a happy demeanor, hypermotoric behavior, and low attention span."

Supports hypermotor/hyperactive behavioral phenotype.

Inappropriate laughter VERY_FREQUENT Inappropriate laughter HP:0000748

Show evidence (1 reference)

PMID:20398390 SUPPORT Human Clinical

"Angelman syndrome (AS) is a neuro-behavioural, genetically determined condition, characterized by ataxic jerky movements, happy sociable disposition and unprovoked bouts of laughter in association with seizures, learning disabilities and language impairment."

Supports characteristic laughter/happy demeanor phenotype.

Tremor Tremor HP:0001337

Show evidence (1 reference)

PMID:20301323 SUPPORT Human Clinical

"Angelman syndrome (AS) is characterized by severe developmental delay or intellectual disability, severe speech impairment, gait ataxia and/or tremulousness of the limbs"

Supports limb tremor/tremulousness as part of the cardinal motor profile.

EEG abnormality VERY_FREQUENT EEG abnormality HP:0002353

Show evidence (2 references)

ORPHA:72 SUPPORT Other

"HP:0002353 | EEG abnormality | Very frequent (99-80%)"

Orphanet phenotype table rates EEG abnormality as very frequent (99-80%).

PMID:14510623 SUPPORT Human Clinical

"Seizures, abnormal electroencephalography, microcephaly, and scoliosis are observed in >80% of patients."

Supports very high prevalence of abnormal EEG.

Cerebral cortical atrophy VERY_FREQUENT Cerebral cortical atrophy HP:0002120

Show evidence (1 reference)

ORPHA:72 SUPPORT Other

"HP:0002120 | Cerebral cortical atrophy | Very frequent (99-80%)"

Orphanet phenotype table rates cerebral cortical atrophy as very frequent (99-80%).

Motor delay VERY_FREQUENT Motor delay HP:0001270

Show evidence (1 reference)

ORPHA:72 SUPPORT Other

"HP:0001270 | Motor delay | Very frequent (99-80%)"

Orphanet phenotype table rates motor delay as very frequent (99-80%).

Autistic behavior VERY_FREQUENT Autistic behavior HP:0000729

Show evidence (1 reference)

ORPHA:72 SUPPORT Other

"HP:0000729 | Autistic behavior | Very frequent (99-80%)"

Orphanet phenotype table rates autistic behavior as very frequent (99-80%).

Self-injurious behavior VERY_FREQUENT Self-injurious behavior HP:0100716

Show evidence (1 reference)

ORPHA:72 SUPPORT Other

"HP:0100716 | Self-injurious behavior | Very frequent (99-80%)"

Orphanet phenotype table rates self-injurious behavior as very frequent (99-80%).

Polyphagia FREQUENT Polyphagia HP:0002591

Show evidence (1 reference)

ORPHA:72 SUPPORT Other

"HP:0002591 | Polyphagia | Frequent (79-30%)"

Orphanet phenotype table rates polyphagia as frequent (79-30%).

Growth 1

Obesity FREQUENT Obesity HP:0001513

Show evidence (1 reference)

ORPHA:72 SUPPORT Other

"HP:0001513 | Obesity | Frequent (79-30%)"

Orphanet phenotype table rates obesity as frequent (79-30%).

Other 5

Iris hypopigmentation Iris hypopigmentation HP:0007730

Show evidence (1 reference)

PMID:41905512 SUPPORT Human Clinical

"Severe iris hypopigmentation (grades 3-4) was unique to the deletion subgroup (33% vs. 0%; P = 0.013), linked to OCA2 codeletion."

Restricts iris hypopigmentation to the deletion subtype, mediated by OCA2 codeletion.

Astigmatism Astigmatism HP:0000483

Show evidence (1 reference)

PMID:41905512 SUPPORT Human Clinical

"High astigmatism (≥2.00 DC) was significantly more prevalent in deletion patients (54% vs 19% [P = 0.004])."

Quantifies the deletion-genotype-specific astigmatism risk.

Broad-based gait VERY_FREQUENT Broad-based gait HP:0002136

Show evidence (1 reference)

ORPHA:72 SUPPORT Other

"HP:0002136 | Broad-based gait | Very frequent (99-80%)"

Orphanet phenotype table rates broad-based gait as very frequent (99-80%).

Protruding tongue FREQUENT Protruding tongue HP:0010808

Show evidence (1 reference)

ORPHA:72 SUPPORT Other

"HP:0010808 | Protruding tongue | Frequent (79-30%)"

Orphanet phenotype table rates protruding tongue as frequent (79-30%).

Recurrent hand flapping FREQUENT Recurrent hand flapping HP:0100023

Show evidence (1 reference)

ORPHA:72 SUPPORT Other

"HP:0100023 | Recurrent hand flapping | Frequent (79-30%)"

Orphanet phenotype table rates recurrent hand flapping as frequent (79-30%).

🧬

Genetic Associations

UBE3A (Causative)

Gene: UBE3A hgnc:12496

Show evidence (2 references)

PMID:33543479 SUPPORT Other

"Angelman syndrome is caused by mutations affecting the maternally inherited UBE3A gene, which encodes an E3-ubiquitin ligase that is critical for typical postnatal brain development."

Supports UBE3A as the primary disease gene.

CGGV:assertion_df25de82-ea9a-4d86-8b42-6587a39650e3-2018-05-02T132344.716Z SUPPORT Other

ClinGen classifies the UBE3A-Angelman syndrome gene-disease relationship as definitive with autosomal dominant inheritance.

15q11.2-q13 maternal deletion and imprinting-region abnormalities (Major molecular classes)

Show evidence (1 reference)

PMID:20301323 SUPPORT Human Clinical

Supports the major non-sequence molecular mechanisms.

GABRB3 (Modifier (deletion subtype))

Gene: GABRB3 hgnc:4083

Show evidence (1 reference)

PMID:30826071 SUPPORT Human Clinical

"deletion of chromosome 15 at 15q11-q13, which encompasses UBE3A and several other genes, including GABRB3, GABRA5, GABRG3, encoding gamma-aminobutyric acid type A receptor subunits (β3, α5, γ3)."

Documents codeletion of GABRB3 with UBE3A in deletion-genotype AS.

GABRA5 (Modifier (deletion subtype))

Gene: GABRA5 hgnc:4079

Show evidence (1 reference)

PMID:30826071 SUPPORT Human Clinical

"hemizygosity of the GABRB3-GABRA5-GABRG3 gene cluster causes abnormal theta and beta EEG oscillations that may underlie the more severe clinical phenotype."

Provides direct evidence for GABRA5 cluster hemizygosity contributing to deletion-AS pathophysiology.

GABRG3 (Modifier (deletion subtype))

Gene: GABRG3 hgnc:4088

Show evidence (1 reference)

PMID:30826071 SUPPORT Human Clinical

"hemizygosity of the GABRB3-GABRA5-GABRG3 gene cluster causes abnormal theta and beta EEG oscillations that may underlie the more severe clinical phenotype."

Supports GABRG3 cluster hemizygosity as part of the deletion-AS modifier locus.

OCA2 (Modifier (deletion subtype))

Gene: OCA2 hgnc:8101

Show evidence (1 reference)

PMID:41905512 SUPPORT Human Clinical

"The 15q11.2-q13 deletions confer a distinct oculoalbinism phenotype mediated by OCA2 haploinsufficiency, featuring high myopia, severe astigmatism, and iris hypopigmentation."

Identifies OCA2 codeletion as the molecular basis for the deletion-specific ophthalmic phenotype.

💊

Medical Actions

Combination anti-seizure pharmacotherapy

Action: Pharmacotherapy NCIT:C15986

Agent: levetiracetam CHEBI:6437 lamotrigine CHEBI:6367 clobazam CHEBI:31413 valproic acid CHEBI:39867

Seizure control is frequently achieved with combination anti-seizure medication regimens, with a newer-agent-forward approach for tolerability.

Mechanism Target:

INHIBITS Disrupted neuronal excitability homeostasis — Anti-seizure medications (levetiracetam, clobazam, valproate, lamotrigine) suppress pathological hyperexcitability arising from reduced UBE3A-dependent regulation of neuronal firing thresholds.

INHIBITS Cortical network hyperexcitability with abnormal EEG background — ASM combination regimens reduce cortical seizure activity and improve the characteristic high-amplitude delta-band EEG background seen in Angelman syndrome.

Target Phenotypes: Seizure HP:0001250

Show evidence (3 references)

PMID:27206232 SUPPORT Human Clinical

"Newer antiepileptic drugs such as levetiracetam, lamotrigine, and clobazam, and to a lesser extent topiramate, appeared to be as effective - if not more so - as valproic acid and clonazepam while offering more favorable side effect profiles."

Supports use of specific newer ASMs with improved tolerability in Angelman syndrome.

PMID:35862628 PARTIAL Other

"Evidence for treating seizures in AS mainly derives from low-quality studies. Levetiracetam and clobazam are the most commonly used ASMs."

Adds review-level context on current ASM usage patterns and evidence limitations.

PMID:20301323 SUPPORT Human Clinical

"Treatment of manifestations: Anti-seizure medication for seizures."

Direct management recommendation for epilepsy in AS.

Highly purified cannabidiol for refractory epilepsy

Action: Pharmacotherapy NCIT:C15986

Agent: cannabidiol CHEBI:69478

Highly purified cannabidiol is being used for refractory epilepsy associated with 15q11.2-q13 deletion (Angelman syndrome) and duplication syndromes; real-world data show meaningful seizure reduction and adjunctive behavioral/sleep benefits with good tolerability.

Mechanism Target:

INHIBITS Disrupted neuronal excitability homeostasis — Cannabidiol modulates neuronal excitability through multiple mechanisms including TRPV1 and GPR55 receptor activity, suppressing refractory myoclonic seizures in the UBE3A-deficient cortical network.

INHIBITS Cortical network hyperexcitability with abnormal EEG background — CBD significantly reduces seizure frequency in refractory AS-associated epilepsy, with particular efficacy against myoclonic seizure types.

Target Phenotypes: Seizure HP:0001250 Sleep disturbance HP:0002360

Show evidence (3 references)

PMID:41992447 SUPPORT Human Clinical

"At last observation, mean seizure reduction was 55.7% (95% confidence interval 38.7-72.7), with 63.6% patients achieving ≥50% reduction, 40.9% achieving ≥75% reduction, and 18.2% achieving seizure freedom."

Quantifies real-world seizure reduction with highly purified CBD in 15q-DDS including Angelman syndrome.

PMID:41992447 PARTIAL Human Clinical

"Tonic seizures in dup15q and myoclonic seizures in AS showed the most notable reductions."

Suggests subtype-specific seizure-type response patterns in AS treated with CBD.

PMID:41992447 SUPPORT Human Clinical

"CBD was well tolerated; no patient discontinued CBD due to side effects alone, and retention at last visit was 81.8%."

Supports tolerability of CBD treatment in AS.

Strabismus surgery

Action: extraocular muscle surgery for strabismus Ontology label: surgical procedure MAXO:0000004

Standardized strabismus surgery (extraocular-muscle surgery) achieves stable ocular alignment in Angelman syndrome regardless of molecular subtype, with high success rates and minimal need for reoperation.

Target Phenotypes: Strabismus HP:0000486

Show evidence (1 reference)

PMID:41905512 SUPPORT Human Clinical

"Surgical success (exodeviation ≤8Δ/esodeviation ≤5Δ at 1 year) was comparable (70% vs 77%; P > 0.05), with minimal exodrift (deletion, -14.9Δ; nondeletion, -12.3Δ) and no reoperations."

Supports strabismus surgery as an effective intervention with comparable success across AS molecular subtypes.

Low-glycemic-index dietary therapy

Action: dietary intervention MAXO:0000088

Low-glycemic-index dietary intervention is used as an adjunctive non-pharmacologic seizure-management strategy, with mixed efficacy signals but good tolerability.

Mechanism Target:

MODULATES Disrupted neuronal excitability homeostasis — Low-glycemic-index dietary therapy stabilizes blood glucose and insulin signaling, reducing metabolic contributions to cortical excitability in Angelman syndrome.

Target Phenotypes: Seizure HP:0001250 Sleep disturbance HP:0002360

Show evidence (2 references)

PMID:27206232 SUPPORT Human Clinical

"The low glycemic index treatment also provided effective seizure control with minimal side effects."

Supports LGIT as an adjunctive dietary option for seizure control.

PMID:41121232 PARTIAL Human Clinical

"INTERPRETATION: While the LGID was well-tolerated and showed trends toward neurocognitive and seizure improvements, results were not statistically significant."

Adds contemporary prospective evidence showing tolerability with non-significant efficacy trends.

Tonsillectomy with enhanced postoperative monitoring

Action: tonsillectomy MAXO:0001081

Tonsillectomy is used in selected Angelman patients with sleep-disordered breathing or sialorrhea, and should be paired with structured postoperative respiratory, pain, and feeding monitoring.

Target Phenotypes: Sleep apnea HP:0010535 Sialorrhea HP:0002307

Show evidence (2 references)

PMID:40776598 SUPPORT Human Clinical

"Twelve children with Angelman syndrome underwent tonsillectomy: 7 for sleep-disordered breathing, 4 for sialorrhea, and 1 for recurrent tonsillitis."

Supports procedure-level use of tonsillectomy for specific clinical indications in Angelman syndrome.

PMID:40776598 SUPPORT Human Clinical

"Nine (75.0%) children experienced postoperative complications, most frequently pooling of secretions and oxygen desaturations."

Supports need for enhanced perioperative and postoperative monitoring after tonsillectomy.

Physical therapy

Action: physical therapy MAXO:0000011

Physical therapy is used to improve mobility and support motor function.

Target Phenotypes: Gait ataxia HP:0002066

Show evidence (1 reference)

PMID:20301323 SUPPORT Human Clinical

"Physical therapy, occupational therapy, and speech therapy with an emphasis on nonverbal methods of communication, including augmentative communication aids (e.g., picture cards, communication boards) and signing."

Supports standard multidisciplinary rehabilitative care.

Occupational therapy

Action: occupational therapy MAXO:0001351

Occupational therapy supports adaptive daily living and motor planning.

Show evidence (1 reference)

PMID:20301323 SUPPORT Human Clinical

Supports occupational therapy as part of standard multidisciplinary care.

Speech therapy and augmentative communication

Action: speech therapy MAXO:0000930

Speech therapy with nonverbal augmentative strategies is recommended due to severe expressive language deficits.

Target Phenotypes: Severe expressive speech impairment HP:0002465

Show evidence (1 reference)

PMID:20301323 SUPPORT Human Clinical

Supports speech-language intervention tailored to severe expressive impairment.

Structured management of gastrointestinal comorbidities

Action: supportive care MAXO:0000950

Ongoing management of reflux, feeding, and constipation is recommended.

Target Phenotypes: Constipation HP:0002019 Gastroesophageal reflux HP:0002020

Show evidence (1 reference)

PMID:20301323 SUPPORT Human Clinical

"Routine management of gastroesophageal reflux, feeding difficulties, constipation, and strabismus."

Supports routine GI-focused symptomatic management.

🔀

Differential Diagnoses

Conditions with similar clinical presentations that must be differentiated from Angelman Syndrome:

Prader-Willi syndrome MONDO:0008300

Overlapping Features Prader-Willi syndrome shares the same imprinted chromosomal region and is a key laboratory differential during molecular workup.

Show evidence (1 reference)

PMID:31235867 SUPPORT Human Clinical

"This article is an update of the best practice guidelines for the molecular analysis of Prader-Willi and Angelman syndromes"

Supports direct diagnostic differentiation at the molecular testing level.

HERC2-related Angelman-like neurodevelopmental disorder Not Yet Curated MONDO:0014224

Overlapping Features HERC2-related disorders can mimic major Angelman features and should be considered in Angelman-like presentations without canonical molecular causes.

Show evidence (1 reference)

PMID:33543479 SUPPORT Other

"For instance, patients with a HERC2 mutation share many clinical features with those who have Angelman syndrome."

Supports HERC2 disorder as a clinically relevant differential.

Houge-Janssens syndrome MONDO:0957553

Overlapping Features Houge-Janssens syndrome can overlap clinically with Angelman syndrome through early neurodevelopmental delay, severe language involvement, seizure risk, and behavioral phenotypes.

Distinguishing Features

Houge-Janssens syndrome is PP2A-subunit related (PPP2R5D, PPP2R1A, PPP2CA, PPP2R5C) rather than UBE3A-imprinting related.
Angelman syndrome is diagnosed through 15q11.2-q13 methylation/UBE3A testing, whereas Houge-Janssens diagnosis relies on PP2A-gene variant identification.

Show evidence (1 reference)

PMID:40555839 SUPPORT Human Clinical

"The core features are neurodevelopmental delay, especially concerning language, prolonged hypotonia, high risk of seizures, and behavior problems."

Supports key symptomatic overlap that makes Houge-Janssens syndrome a relevant clinical differential.

📊

Related Datasets

Channelopathy pathogenesis in a human neural cell model of Angelman Syndrome geo:GSE120225

RNA-seq dataset from human induced neurons and 3D cortical organoids derived from Angelman patient iPSCs and UBE3A-knockout hESC lines, used to study network hyperexcitability mechanisms.

human BULK RNA SEQ n=6

Conditions: Angelman syndrome iPSC-derived neural model UBE3A-knockout hESC-derived neural model control neural model

Show evidence (1 reference)

GEO:GSE120225 SUPPORT In Vitro

"Here, by utilizing human induced neurons and 3D cortical organoids derived from AS patient iPSCs and CRISPR-Cas9 mediated UBE3A KO hESCs, we uncovered a novel role of UBE3A in suppressing neuronal hyperexcitability via ubiquitin-mediated degradation of BK channels."

Supports relevance for human-cell-model mechanisms linking UBE3A loss to neuronal hyperexcitability.

Differences in transcription in Angelman syndrome and control person iPSC-derived neurons geo:GSE146640

Human iPSC-neuron transcriptome dataset comparing Angelman syndrome and control lines to characterize disease-associated transcriptional changes.

human BULK RNA SEQ n=6

Conditions: Angelman syndrome iPSC-derived neurons control iPSC-derived neurons

Show evidence (1 reference)

GEO:GSE146640 SUPPORT In Vitro

"So we wanted to study differences in the transcriptome in neurons differentiated from iPSCs that were derived from patients with Angleman syndrome and normal controls."

Supports direct disease-vs-control transcriptomic comparison in human neuron-like cells.

Establishing a molecular phenotype for Angelman Syndrome stem cell-derived neurons geo:GSE160747

Human stem-cell neuron RNA-seq dataset spanning isogenic control versus Angelman syndrome neuronal models and antisense-oligonucleotide intervention conditions relevant to UBE3A reinstatement biology.

human BULK RNA SEQ n=36

Conditions: isogenic control and Angelman syndrome pluripotent stem cell-derived neurons UBE3A ASO-treated H9 hESC-derived neurons scramble ASO-treated H9 hESC-derived neurons

Show evidence (1 reference)

GEO:GSE160747 SUPPORT In Vitro

"mRNAseq on (1) isogenic control and Angelman Syndrome pluripotent stem cell-derived neurons or (2) antisense oligonucleotide-treated H9 hESC-derived neurons"

Supports mechanistically relevant transcriptomic profiling in human AS neuronal models and ASO-treated conditions.

UBE3A reinstatement restores behavior and proteome in an Angelman syndrome mouse model of imprinting defects geo:GSE284678

Mouse RNA-seq resource from an imprinting-center Angelman model (mICD/UPD relevant) with UBE3A reinstatement interventions to evaluate rescue of molecular and behavioral phenotypes.

house mouse BULK RNA SEQ n=14

Conditions: mICD Angelman model mice UBE3A reinstatement conditions control mice

PMID:40877933

Show evidence (2 references)

GEO:GSE284678 SUPPORT Model Organism

"mICD mice showed significant reduction in UBE3A protein, bi-allelic expression of Ube3a-ATS and Mkrn3-Snord115 gene cluster, leading to robust AS behavioral deficits and proteome alterations similar to Ube3aKO mice."

Supports utility of this model for transcriptomic interrogation of imprinting-related Angelman pathophysiology.

GEO:GSE284678 SUPPORT Model Organism

"Genetic UBE3A overexpression in mICD mice, mimicking therapeutic strategies that effectively activate the biallelic silenced Ube3a gene, resulted in a complete rescue of all behavioral and proteome alterations."

Adds mechanistic rescue context relevant to disease-modifying therapy modeling.

Differential Gene Expression in Angelman syndrome deletion vs. int dup(15) Human Lymphocytes geo:GSE32563

Human peripheral-blood microarray dataset comparing Angelman deletion cases and reciprocal 15q duplication cases to identify shared and divergent transcriptional signatures.

human MICROARRAY n=6

Conditions: Angelman syndrome deletion interstitial duplication 15q autism

Show evidence (1 reference)

GEO:GSE32563 SUPPORT Human Clinical

"Microarray analysis revealed 1225 genes that were elevated in AS deletion vs int dup(15) and 976 genes that were elevated in int dup(15) vs AS deletion PBMC (pvalue<0.05)."

Supports this dataset as a human comparative transcriptomic resource connected to UBE3A-region disorders.

🔬

Clinical Trials

NCT04428281 PHASE_I COMPLETED

Open-label intrathecal antisense-oligonucleotide trial evaluating RO7248824 safety, tolerability, PK, and PD in participants with Angelman syndrome.

Show evidence (1 reference)

clinicaltrials:NCT04428281 SUPPORT Human Clinical

"This is a phase I, multicenter, non-randomized, adaptive, open-label, multiple ascending, intra-participant, dose-escalation study with a long-term extension (LTE) part and an optional open-label extension (OOE) part."

Supports active clinical development of UBE3A-unsilencing therapy.

NCT04259281 PHASE_I COMPLETED

Early-phase intrathecal GTX-102 antisense-oligonucleotide study (Phase 1/2) in pediatric Angelman syndrome.

Show evidence (1 reference)

clinicaltrials:NCT04259281 SUPPORT Human Clinical

"The primary objective of the study is to evaluate the safety and tolerability of multiple-ascending doses of GTX-102 administered by intrathecal (IT) injection to participants with Angelman Syndrome (AS)."

Supports clinical translation of UBE3A-restoration strategies.

NCT04106557 PHASE_III COMPLETED

Randomized placebo-controlled phase III study of oral OV101 (gaboxadol) in pediatric Angelman syndrome.

Target Phenotypes: Sleep disturbance HP:0002360

Show evidence (1 reference)

clinicaltrials:NCT04106557 SUPPORT Human Clinical

"The purpose of this study is to assess the efficacy and safety of oral OV101 (gaboxadol) in pediatric subjects with Angelman syndrome."

Supports late-stage therapeutic evaluation in AS.

NCT05127226 PHASE_I RECRUITING

HALOS - intrathecal antisense oligonucleotide ION582 (Ionis) safety, tolerability, pharmacokinetics, and pharmacodynamics study in participants with Angelman syndrome.

Show evidence (1 reference)

clinicaltrials:NCT05127226 SUPPORT Human Clinical

"The purpose of this study is to evaluate the safety and tolerability of ascending doses of ION582 administered intrathecally in participants with Angelman syndrome."

Supports active clinical evaluation of an alternative ASO program (ION582) for paternal UBE3A reactivation.

NCT06617429 PHASE_III ACTIVE_NOT_RECRUITING

Phase 3, randomized, double-blind, sham-controlled study evaluating intrathecal GTX-102 (apazunersen) for cognitive function in pediatric deletion-type Angelman syndrome.

Target Phenotypes: Severe intellectual disability HP:0010864

Show evidence (1 reference)

clinicaltrials:NCT06617429 SUPPORT Human Clinical

"The primary objective of this study is to evaluate the effect of GTX-102 in cognitive function in participants with deletion-type Angelman Syndrome (AS)."

Supports pivotal Phase 3 evaluation of UBE3A-restoring ASO therapy in deletion-type AS.

NCT07157254 PHASE_II RECRUITING

Phase 2 open-label basket study of GTX-102 in adult and pediatric subjects with deletion- or non-deletion-type Angelman syndrome to evaluate safety and efficacy across genotypes.

Show evidence (1 reference)

clinicaltrials:NCT07157254 SUPPORT Human Clinical

"The main goal of the study is to evaluate the safety and efficacy of GTX-102 in participants with Angelman syndrome."

Supports basket evaluation of GTX-102 across all major AS molecular subtypes.

NCT06415344 PHASE_III ENROLLING_BY_INVITATION

Long-term extension trial of intrathecal GTX-102 (apazunersen) evaluating long-term safety and efficacy in participants with Angelman syndrome who completed prior GTX-102 studies.

Show evidence (1 reference)

clinicaltrials:NCT06415344 SUPPORT Human Clinical

"The primary objective of the study is to evaluate the long-term safety profile of GTX-102 in participants with Angelman Syndrome (AS)"

Supports long-term safety follow-up for the GTX-102 ASO program.

{ }

Source YAML

click to show

name: Angelman Syndrome
creation_date: '2026-03-03T02:33:07Z'
updated_date: '2026-05-05T12:15:36Z'
category: Mendelian
description: >-
  Angelman syndrome is a neurogenetic imprinting disorder caused by deficient
  neuronal expression of the maternally inherited UBE3A allele, with severe
  developmental impairment, minimal speech, gait ataxia, seizures, and a
  characteristic behavioral phenotype.
disease_term:
  preferred_term: Angelman syndrome
  term:
    id: MONDO:0007113
    label: Angelman syndrome
mappings:
  icd10cm_mappings:
  - term:
      id: ICD10CM:Q93.5
      label: Other deletions of part of a chromosome
    mapping_predicate: skos:narrowMatch
    mapping_source: ORPHA:72
    mapping_justification: Orphanet lists ICD-10 Q93.5 as a narrower cross-reference for Angelman syndrome.
    consistency:
    - reference: ORPHA:72
      consistent: CONSISTENT
      notes: "ICD-10:Q93.5 | Narrower"
  mondo_mappings:
  - term:
      id: MONDO:0007113
      label: Angelman syndrome
    mapping_predicate: skos:exactMatch
    mapping_source: ORPHA:72
    mapping_justification: Orphanet lists MONDO:0007113 as an exact cross-reference for Angelman syndrome.
    consistency:
    - reference: ORPHA:72
      consistent: CONSISTENT
      notes: "MONDO:0007113 | Exact"
classifications:
  harrisons_chapter:
  - classification_value: GENETICS_ENVIRONMENT_DISEASE
    evidence:
    - reference: PMID:35150089
      reference_title: "A multidisciplinary approach and consensus statement to establish standards of care for Angelman syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "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."
      explanation: Supports classification as a hereditary genetic disorder.
  - classification_value: NEUROLOGIC
    evidence:
    - reference: PMID:24876791
      reference_title: "Angelman syndrome: review of clinical and molecular aspects."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: '"Angelman syndrome" (AS) is a neurodevelopmental disorder whose main features are intellectual disability, lack of speech, seizures, and a characteristic behavioral profile.'
      explanation: Supports classification as a nervous system/neurodevelopmental disorder.
definitions:
- name: Clinical syndrome definition
  definition_type: CASE_DEFINITION
  description: >-
    Angelman syndrome is defined clinically by severe developmental delay or
    intellectual disability, severe speech impairment, ataxic movement disorder,
    characteristic happy demeanor, and frequent co-occurrence of seizures and
    microcephaly.
  scope: Core clinical phenotype in pediatric and adult practice
  evidence:
  - reference: PMID:20301323
    reference_title: "Angelman Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Angelman syndrome (AS) is characterized by severe developmental delay or intellectual disability, severe speech impairment, gait ataxia and/or tremulousness of the limbs, and unique behavior with an apparent happy demeanor that includes frequent laughing, smiling, and excitability."
    explanation: Defines the canonical clinical syndrome.
  - reference: PMID:20301323
    reference_title: "Angelman Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Microcephaly and seizures are also common."
    explanation: Adds core neurologic features used in clinical recognition.
- name: Orphanet disease definition
  definition_type: CASE_DEFINITION
  description: >-
    Orphanet defines Angelman syndrome as a rare genetic neurodevelopmental
    disorder characterized by moderate to severe intellectual disability,
    microcephaly, seizures, ataxic gait and distinct abnormal facial shape.
  evidence:
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "A rare genetic neurodevelopmental disorder characterized by moderate to severe intellectual disability, microcephaly, seizures, ataxic gait and distinct abnormal facial shape."
    explanation: Orphanet's definition supports the neurodevelopmental disorder framing of this entry.
- name: Molecular diagnostic criteria framework
  definition_type: DIAGNOSTIC_CRITERIA
  description: >-
    Molecular diagnosis is primarily established by 15q11.2-q13 methylation
    testing with reflex UBE3A sequence analysis when methylation testing is
    negative.
  scope: Molecular confirmation strategy for suspected Angelman syndrome
  evidence:
  - reference: PMID:20301323
    reference_title: "Angelman Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Analysis of parent-specific DNA methylation imprints in the 15q11.2-q13 chromosome region detects approximately 80% of individuals with AS, including those with a deletion, uniparental disomy, or an imprinting defect; fewer than 1% of individuals have a cytogenetically visible chromosome rearrangement (e.g., translocation or inversion)."
    explanation: Supports methylation analysis as first-line molecular testing.
  - reference: PMID:20301323
    reference_title: "Angelman Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "UBE3A sequence analysis detects pathogenic variants in an additional approximately 11% of individuals."
    explanation: Supports second-tier sequencing for methylation-negative cases.
parents:
- Neurodevelopmental disorder
- Imprinting disorder
synonyms:
- AS
- Angelman's syndrome
- happy puppet syndrome (deprecated)
external_assertions:
- name: Orphanet Angelman syndrome record
  source: Orphanet
  assertion_type: Structured disease record
  external_id: ORPHA:72
  url: http://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=en&Expert=72
  description: >-
    Orphanet structured record for Angelman syndrome, including curated
    cross-references to MONDO, ICD-10, ICD-11, OMIM, MeSH, MedDRA, and UMLS
    identifiers.
  evidence:
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "MONDO:0007113 | Exact"
    explanation: The Orphanet cross-reference table exactly maps ORPHA:72 to MONDO:0007113.
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "ICD-10:Q93.5 | Narrower"
    explanation: The Orphanet cross-reference table maps ORPHA:72 to ICD-10 Q93.5 as a narrower match.
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "ICD-11:LD90.0 | Exact"
    explanation: The Orphanet cross-reference table exactly maps ORPHA:72 to ICD-11 LD90.0.
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "OMIM:105830 | Exact"
    explanation: The Orphanet cross-reference table exactly maps ORPHA:72 to OMIM 105830.
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "UMLS:C0162635 | Exact"
    explanation: The Orphanet cross-reference table exactly maps ORPHA:72 to UMLS C0162635.
has_subtypes:
- name: Maternal 15q11.2-q13 deletion Angelman syndrome
  classification: molecular
  subtype_frequency: 70%
  description: >-
    Most common molecular subtype, caused by de novo deletion of the maternally
    inherited 15q11.2-q13 region including UBE3A. The deletion frequently spans
    the GABRB3-GABRA5-GABRG3 GABA-A receptor subunit cluster and OCA2, contributing
    to a more severe and earlier-onset epilepsy phenotype and to oculocutaneous
    hypopigmentation features distinguishing this subtype.
  evidence:
  - reference: PMID:14510623
    reference_title: "Angelman syndrome: etiology, clinical features, diagnosis, and management of symptoms."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Approximately 70% of patients show a deletion involving the maternally inherited chromosome 15q11-q13, encompassing a cluster of gamma-aminobutyric acid receptor subunit genes"
    explanation: Quantifies and defines the major deletion subtype.
  - reference: PMID:34536900
    reference_title: "Clinical Characterization of Epilepsy in Children With Angelman Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Epilepsy was reported in a greater proportion of individuals with a deletion than a nondeletion genotype"
    explanation: Quantifies the higher epilepsy burden in deletion-genotype Angelman syndrome.
  - reference: PMID:34536900
    reference_title: "Clinical Characterization of Epilepsy in Children With Angelman Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "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."
    explanation: Establishes earlier seizure onset and more severe epilepsy phenotype in deletion-genotype AS.
  - reference: PMID:30826071
    reference_title: "Electrophysiological Phenotype in Angelman Syndrome Differs Between Genotypes."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Our results provide strong evidence for the contribution of non-UBE3A neuronal pathophysiology in deletion AS and suggest that hemizygosity of the GABRB3-GABRA5-GABRG3 gene cluster causes abnormal theta and beta EEG oscillations that may underlie the more severe clinical phenotype."
    explanation: Supports GABA-A receptor cluster hemizygosity as a deletion-specific pathophysiologic modifier.
  - reference: PMID:41905512
    reference_title: "Ophthalmic phenotype and strabismus surgery in Angelman syndrome: genotype-specific risks and uniform surgical efficacy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The 15q11.2-q13 deletions confer a distinct oculoalbinism phenotype mediated by OCA2 haploinsufficiency, featuring high myopia, severe astigmatism, and iris hypopigmentation."
    explanation: Defines the deletion-specific oculoalbinism phenotype through OCA2 codeletion.
- name: UBE3A pathogenic variant Angelman syndrome
  classification: molecular
  subtype_frequency: 6-11%
  description: >-
    Subtype caused by pathogenic variants in maternally inherited UBE3A.
  genes:
  - preferred_term: UBE3A
    term:
      id: hgnc:12496
      label: UBE3A
  evidence:
  - reference: PMID:14510623
    reference_title: "Angelman syndrome: etiology, clinical features, diagnosis, and management of symptoms."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "6% harbor intragenic mutations of the ubiquitin-protein ligase E3A (UBE3A) gene."
    explanation: Supports a distinct UBE3A-variant molecular subtype.
  - reference: PMID:20301323
    reference_title: "Angelman Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "UBE3A sequence analysis detects pathogenic variants in an additional approximately 11% of individuals."
    explanation: Provides an additional estimate from a contemporary GeneReviews summary.
- name: Paternal uniparental disomy 15 Angelman syndrome
  classification: molecular
  subtype_frequency: 3%
  description: >-
    Subtype caused by paternal uniparental disomy of chromosome 15 with absent
    functional maternal UBE3A contribution in neurons.
  evidence:
  - reference: PMID:14510623
    reference_title: "Angelman syndrome: etiology, clinical features, diagnosis, and management of symptoms."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "3% show chromosome 15 paternal uniparental disomy (UPD)"
    explanation: Supports UPD as a recognized molecular subtype.
- name: Imprinting defect Angelman syndrome
  classification: molecular
  subtype_frequency: 1%
  description: >-
    Subtype caused by imprinting center defects disrupting maternal-expression
    pattern at the 15q11.2-q13 locus.
  evidence:
  - reference: PMID:14510623
    reference_title: "Angelman syndrome: etiology, clinical features, diagnosis, and management of symptoms."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "1% harbor a mutation in the imprinting center (a transcriptional regulatory element)"
    explanation: Supports imprinting-center defects as a rarer molecular subtype.
inheritance:
- name: Autosomal dominant inheritance with maternal imprinting
  inheritance_term:
    preferred_term: Autosomal dominant inheritance with maternal imprinting
    term:
      id: HP:0012275
      label: Autosomal dominant inheritance with maternal imprinting
  penetrance: COMPLETE
  description: >-
    Disease expression requires loss of the maternally inherited functional UBE3A
    allele in neurons; most cases are simplex/de novo.
  evidence:
  - reference: PMID:20301323
    reference_title: "Angelman Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Individuals with AS typically represent simplex cases (i.e., a single affected family member) and have the disorder as the result of a de novo genetic alteration associated with a very low recurrence risk."
    explanation: Supports predominant de novo occurrence in clinical practice.
  - reference: PMID:20301323
    reference_title: "Angelman Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Less commonly, an individual with AS has the disorder as the result of a genetic alteration associated with an imprinting pattern of autosomal dominant inheritance or variable recurrence risk."
    explanation: Supports the imprinting-associated autosomal dominant inheritance mechanism.
prevalence:
- population: Global
  notes: Birth incidence is consistently reported in the rare-disease range.
  evidence:
  - reference: PMID:35150089
    reference_title: "A multidisciplinary approach and consensus statement to establish standards of care for Angelman syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Angelman syndrome (AS) is a rare neurogenetic disorder present in approximately 1/12,000 individuals"
    explanation: Supports a contemporary prevalence estimate.
  - reference: PMID:25428759
    reference_title: "Angelman syndrome in adulthood."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "AS has an estimated incidence of approximately 1 in 12,000-20,000 live births, but life expectancy by epidemiologic measures remains unknown"
    explanation: Adds an incidence range used in natural-history literature.
- population: Worldwide (Orphanet point prevalence)
  notes: Orphanet reports a worldwide point-prevalence class of 1-9 per 100,000.
  evidence:
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "1-9 / 100 000 | Worldwide | Point prevalence | PMID:20301323,PMID:21587322,EXPERT"
    explanation: The Orphanet epidemiology table provides a worldwide point-prevalence class for Angelman syndrome.
- population: Australia
  notes: Orphanet reports Australian prevalence at birth and point prevalence of 1-9 per 100,000.
  evidence:
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "1-9 / 100 000 | Australia | Prevalence at birth | PMID:16492624"
    explanation: Orphanet epidemiology table provides Australian prevalence at birth.
- population: Denmark
  notes: Orphanet reports a Danish point prevalence of 1-5 per 10,000 and prevalence at birth of 1-9 per 1,000,000.
  evidence:
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "1-5 / 10 000 | Denmark | Point prevalence | PMID:7573182"
    explanation: Orphanet epidemiology table provides Danish point prevalence estimate.
- population: Estonia
  notes: Orphanet reports Estonian prevalence at birth and point prevalence of 1-9 per 100,000.
  evidence:
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "1-9 / 100 000 | Estonia | Point prevalence | PMID:16906556"
    explanation: Orphanet epidemiology table provides Estonian prevalence estimate.
- population: United Kingdom
  notes: Orphanet reports a UK point prevalence of 1-9 per 100,000.
  evidence:
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "1-9 / 100 000 | United Kingdom | Point prevalence | PMID:21152085"
    explanation: Orphanet epidemiology table provides UK point prevalence estimate.
progression:
- phase: Early infancy developmental divergence
  age_range: ~6-12 months
  notes: Developmental delay becomes clinically recognizable in late infancy.
  evidence:
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Age of onset: Infancy"
    explanation: Orphanet records infancy as the age of onset for Angelman syndrome.
  - reference: PMID:20301323
    reference_title: "Angelman Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Developmental delays are first noted at around age six months; however, the unique clinical features of AS do not become manifest until after age one year."
    explanation: Defines early timing of symptom emergence.
  - reference: PMID:14510623
    reference_title: "Angelman syndrome: etiology, clinical features, diagnosis, and management of symptoms."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Clinical findings present in all patients include developmental delay, which becomes apparent by 6-12 months of age"
    explanation: Independent support for infancy-onset developmental divergence.
- phase: Early childhood seizure onset
  age_range: first 3 years
  notes: Epilepsy usually appears in early childhood, with lower frequency in the first year.
  evidence:
  - reference: PMID:20398390
    reference_title: "Epilepsy in patients with Angelman syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Epilepsy, often severe and hard to control, is present in 85% of patients within the first three years of life, although less than 25% develop seizures during the first year."
    explanation: Supports timing and burden of early epilepsy.
- phase: Adolescent/adult neurologic trajectory
  notes: >-
    Seizure burden often improves after childhood but can recur in adulthood;
    sleep dysfunction remains prevalent over the life course.
  evidence:
  - reference: PMID:25428759
    reference_title: "Angelman syndrome in adulthood."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The results of this study indicate that epilepsy severity may assume a bimodal age distribution: seizures are typically most severe in early childhood but may recur in adulthood."
    explanation: Supports age-dependent progression and recurrence pattern.
  - reference: PMID:25428759
    reference_title: "Angelman syndrome in adulthood."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "While late-adolescent and adult sleep patterns were improved when compared to the degree of sleep dysfunction present during infancy and childhood, the prevalence of poor sleep in adults remained quite high."
    explanation: Supports persistence of sleep-related morbidity into adulthood.
pathophysiology:
- name: Maternal UBE3A allele disruption
  description: >-
    Angelman syndrome is initiated by disruption of the maternally inherited
    UBE3A allele (deletion, pathogenic variant, UPD context, or imprinting
    defect).
  genes:
  - preferred_term: UBE3A
    term:
      id: hgnc:12496
      label: UBE3A
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  locations:
  - preferred_term: nervous system
    term:
      id: UBERON:0001016
      label: nervous system
  downstream:
  - target: Neuron-specific paternal UBE3A silencing
    description: Neuronal imprinting limits compensatory expression from the paternal allele.
    evidence:
    - reference: PMID:24876791
      reference_title: "Angelman syndrome: review of clinical and molecular aspects."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "AS is due to deficient expression of the ubiquitin protein ligase E3A (UBE3A) gene, which displays paternal imprinting."
      explanation: Links maternal UBE3A disruption with imprinting-dependent inability to compensate.
  evidence:
  - reference: PMID:33543479
    reference_title: "UBE3A reinstatement as a disease-modifying therapy for Angelman syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Angelman syndrome is caused by mutations affecting the maternally inherited UBE3A gene, which encodes an E3-ubiquitin ligase that is critical for typical postnatal brain development."
    explanation: Establishes the initiating molecular lesion.
- name: Neuron-specific paternal UBE3A silencing
  description: >-
    In neurons, the paternal UBE3A allele is silenced by imprinting, so maternal
    disruption leads to loss of effective neuronal UBE3A expression.
  genes:
  - preferred_term: UBE3A
    term:
      id: hgnc:12496
      label: UBE3A
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  locations:
  - preferred_term: nervous system
    term:
      id: UBERON:0001016
      label: nervous system
  downstream:
  - target: Reduced neuronal UBE3A protein abundance
    description: Effective neuronal UBE3A protein dosage falls below physiologic levels.
    evidence:
    - reference: PMID:33543479
      reference_title: "UBE3A reinstatement as a disease-modifying therapy for Angelman syndrome."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "Angelman syndrome is caused by the loss of UBE3A protein."
      explanation: Supports direct protein-level consequence of imprinting plus maternal disruption.
  evidence:
  - reference: PMID:33543479
    reference_title: "UBE3A reinstatement as a disease-modifying therapy for Angelman syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "in neurons only the maternally inherited UBE3A gene is expressed."
    explanation: Supports neuron-specific imprinting mechanism.
- name: Reduced neuronal UBE3A protein abundance
  description: >-
    Loss of UBE3A protein in neurons reduces E3-ligase-dependent control of
    protein turnover signaling.
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  locations:
  - preferred_term: brain
    term:
      id: UBERON:0000955
      label: brain
  downstream:
  - target: Decreased UBE3A-mediated protein ubiquitination
    description: Lower UBE3A dosage reduces normal ubiquitination activity in neuronal systems.
    evidence:
    - reference: PMID:33543479
      reference_title: "UBE3A reinstatement as a disease-modifying therapy for Angelman syndrome."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "Angelman syndrome is caused by mutations affecting the maternally inherited UBE3A gene, which encodes an E3-ubiquitin ligase that is critical for typical postnatal brain development."
      explanation: Supports causal transition from reduced UBE3A protein to decreased E3 ligase function.
  evidence:
  - reference: PMID:33543479
    reference_title: "UBE3A reinstatement as a disease-modifying therapy for Angelman syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Angelman syndrome is caused by the loss of UBE3A protein."
    explanation: Supports this discrete protein-abundance event.
  - reference: PMID:40671377
    reference_title: "The Ubiquitin E3 Ligase UBE3A Regulates GRIPAP1 and PACSIN1 Proteins Linked to the Endocytic Recycling of AMPA Receptors."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "AS arises due to the neuronal loss of UBE3A, an E3 ligase that regulates protein abundance through the addition of lysine 48 (K48)-linked polyubiquitin chains to proteins targeted for degradation by the ubiquitin proteasome system (UPS)."
    explanation: Human iPSC-derived cortical-neuron study provides direct molecular support linking neuronal UBE3A loss to altered ubiquitin-dependent protein regulation.
- name: Decreased UBE3A-mediated protein ubiquitination
  description: >-
    UBE3A-dependent ubiquitination signaling is reduced, with downstream
    dysregulation of protein-stability control.
  biological_processes:
  - preferred_term: protein ubiquitination
    modifier: DECREASED
    term:
      id: GO:0016567
      label: protein ubiquitination
  - preferred_term: regulation of protein stability
    modifier: DYSREGULATED
    term:
      id: GO:0031647
      label: regulation of protein stability
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  locations:
  - preferred_term: brain
    term:
      id: UBERON:0000955
      label: brain
  downstream:
  - target: Dysregulated neuronal signaling pathways
    description: Loss of ubiquitination control contributes to broad pathway-level signaling derangement.
    evidence:
    - reference: PMID:33543479
      reference_title: "UBE3A reinstatement as a disease-modifying therapy for Angelman syndrome."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "Loss of UBE3A affects multiple signalling pathways in the brain."
      explanation: Supports pathway-level consequences of UBE3A-dependent signaling loss.
    - reference: PMID:40310720
      reference_title: "Activity-dependent degradation of Kv4.2 contributes to synaptic plasticity and behavior in Angelman syndrome model mice."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "Here, we show the voltage-gated K+ channel Kv4.2 as an activity-dependent substrate for UBE3A."
      explanation: Mouse-model evidence supports a specific downstream UBE3A signaling substrate contributing to pathway dysregulation.
  evidence:
  - reference: PMID:33543479
    reference_title: "UBE3A reinstatement as a disease-modifying therapy for Angelman syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Loss of UBE3A affects multiple signalling pathways in the brain."
    explanation: Supports broad neuronal signaling dysregulation downstream of reduced ubiquitination control.
  - reference: PMID:40671377
    reference_title: "The Ubiquitin E3 Ligase UBE3A Regulates GRIPAP1 and PACSIN1 Proteins Linked to the Endocytic Recycling of AMPA Receptors."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "We provide evidence UBE3A polyubiquitinates PACSIN1 and GRIPAP1 to regulate protein turnover, with potential implications for impaired activity-dependent synaptic plasticity observed in AS."
    explanation: Adds direct mechanistic evidence that UBE3A-dependent ubiquitination regulates neuronal protein turnover linked to synaptic dysfunction.
- name: Dysregulated neuronal signaling pathways
  description: >-
    Multiple brain signaling pathways become dysregulated rather than a single
    isolated pathway defect.
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  locations:
  - preferred_term: brain
    term:
      id: UBERON:0000955
      label: brain
  downstream:
  - target: Impaired experience-dependent synaptic remodeling
    description: Broad pathway dysregulation contributes to synaptic plasticity and remodeling defects.
    evidence:
    - reference: PMID:24876791
      reference_title: "Angelman syndrome: review of clinical and molecular aspects."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "Studies of mouse models of AS have implicated UBE3A in experience-dependent synaptic remodeling."
      explanation: Supports causal transition from pathway dysregulation to impaired synaptic remodeling.
  evidence:
  - reference: PMID:33543479
    reference_title: "UBE3A reinstatement as a disease-modifying therapy for Angelman syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "given the multitude of signalling mechanisms that are derailed, it is unlikely that targeting a single pathway is going to be very effective."
    explanation: Supports multipathway dysregulation framing.
- name: Impaired experience-dependent synaptic remodeling
  description: >-
    UBE3A-related network pathology impairs synaptic organization and remodeling
    in neuronal circuits.
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  locations:
  - preferred_term: cerebral cortex
    term:
      id: UBERON:0000956
      label: cerebral cortex
  biological_processes:
  - preferred_term: synapse organization
    modifier: DYSREGULATED
    term:
      id: GO:0050808
      label: synapse organization
  downstream:
  - target: Disrupted neuronal excitability homeostasis
    description: Synaptic remodeling defects alter network excitability and transmission balance.
    evidence:
    - reference: PMID:33543479
      reference_title: "UBE3A reinstatement as a disease-modifying therapy for Angelman syndrome."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "It has been consistently shown that mouse models of Angelman syndrome show marked changes in synaptic plasticity and excitatory/inhibitory balance."
      explanation: Supports progression from synaptic remodeling defects to altered excitability balance.
  - target: Severe intellectual disability
    description: Synaptic remodeling dysfunction contributes to severe cognitive impairment.
    evidence:
    - reference: PMID:20301323
      reference_title: "Angelman Syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Angelman syndrome (AS) is characterized by severe developmental delay or intellectual disability, severe speech impairment"
      explanation: Supports downstream neurodevelopmental cognitive outcome.
  - target: Severe speech impairment
    description: Synaptic-network disruption contributes to profound expressive language deficits.
    evidence:
    - reference: PMID:20301323
      reference_title: "Angelman Syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Angelman syndrome (AS) is characterized by severe developmental delay or intellectual disability, severe speech impairment"
      explanation: Supports downstream language phenotype.
  - target: Gait ataxia
    description: Network-level motor-circuit dysfunction contributes to persistent gait ataxia.
    evidence:
    - reference: PMID:20301323
      reference_title: "Angelman Syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Angelman syndrome (AS) is characterized by severe developmental delay or intellectual disability, severe speech impairment, gait ataxia and/or tremulousness of the limbs"
      explanation: Supports downstream motor phenotype.
  - target: Global developmental delay
    description: Synaptic remodeling failure across cortical circuits manifests as universal early developmental delay.
    evidence:
    - reference: PMID:14510623
      reference_title: "Angelman syndrome: etiology, clinical features, diagnosis, and management of symptoms."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Clinical findings present in all patients include developmental delay, which becomes apparent by 6-12 months of age"
      explanation: Supports downstream global developmental delay phenotype.
  - target: Microcephaly
    description: UBE3A-dependent neuronal/synaptic developmental defects contribute to acquired postnatal microcephaly.
    evidence:
    - reference: PMID:14510623
      reference_title: "Angelman syndrome: etiology, clinical features, diagnosis, and management of symptoms."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Seizures, abnormal electroencephalography, microcephaly, and scoliosis are observed in >80% of patients."
      explanation: Supports downstream microcephaly phenotype linked to UBE3A-related neurodevelopmental disruption.
  - target: Tremor
    description: Synaptic remodeling defects in motor circuits produce limb tremulousness.
    evidence:
    - reference: PMID:20301323
      reference_title: "Angelman Syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Angelman syndrome (AS) is characterized by severe developmental delay or intellectual disability, severe speech impairment, gait ataxia and/or tremulousness of the limbs"
      explanation: Supports downstream tremor (tremulousness of the limbs) phenotype.
  - target: Hyperactivity
    description: Cortical and limbic synaptic-circuit dysfunction contributes to hypermotoric/hyperactive behavior.
    evidence:
    - reference: PMID:14510623
      reference_title: "Angelman syndrome: etiology, clinical features, diagnosis, and management of symptoms."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "a typical behavioral profile, including a happy demeanor, hypermotoric behavior, and low attention span."
      explanation: Supports downstream hypermotoric/hyperactive behavioral phenotype.
  - target: Inappropriate laughter
    description: Disrupted limbic-cortical synaptic networks contribute to the characteristic happy demeanor and unprovoked laughter.
    evidence:
    - reference: PMID:24876791
      reference_title: "Angelman syndrome: review of clinical and molecular aspects."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "The behavioral features of AS include a happy demeanor, easily provoked laughter, short attention span, hypermotoric behavior, mouthing of objects, sleep disturbance, and an affinity for water."
      explanation: Supports downstream characteristic behavioral phenotype of inappropriate laughter.
  - target: Scoliosis
    description: Hypotonia and motor-circuit dysfunction secondary to synaptic remodeling defects predispose to progressive spinal curvature.
    evidence:
    - reference: PMID:14510623
      reference_title: "Angelman syndrome: etiology, clinical features, diagnosis, and management of symptoms."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Seizures, abnormal electroencephalography, microcephaly, and scoliosis are observed in >80% of patients."
      explanation: Supports scoliosis as a high-prevalence downstream musculoskeletal manifestation co-occurring with motor/CNS phenotypes.
  evidence:
  - reference: PMID:24876791
    reference_title: "Angelman syndrome: review of clinical and molecular aspects."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Studies of mouse models of AS have implicated UBE3A in experience-dependent synaptic remodeling."
    explanation: Supports this discrete synaptic-remodeling event.
  - reference: PMID:36237484
    reference_title: "Lack of UBE3A-Mediated Regulation of Synaptic SK2 Channels Contributes to Learning and Memory Impairment in the Female Mouse Model of Angelman Syndrome."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Like in male AS mice, long-term potentiation (LTP) was significantly reduced while long-term depression (LTD) was enhanced at hippocampal CA3-CA1 synapses of female AS mice, as compared to female WT mice."
    explanation: Provides synapse-level electrophysiologic evidence for impaired plasticity in Angelman model systems.
  - reference: PMID:40310720
    reference_title: "Activity-dependent degradation of Kv4.2 contributes to synaptic plasticity and behavior in Angelman syndrome model mice."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Moreover, deficits in mEPSC frequency and spike-timing-dependent long-term potentiation, as well as certain behaviors including cognitive inflexibility found in AS mice, are rescued when bred with Kv4.2 conditional knockout mice."
    explanation: Supports causal linkage between UBE3A downstream signaling defects and synaptic plasticity abnormalities.
- name: Disrupted neuronal excitability homeostasis
  description: >-
    Neuronal excitatory/inhibitory balance and electrophysiologic homeostasis are
    disrupted in cortical networks.
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  locations:
  - preferred_term: cerebral cortex
    term:
      id: UBERON:0000956
      label: cerebral cortex
  biological_processes:
  - preferred_term: modulation of chemical synaptic transmission
    modifier: DYSREGULATED
    term:
      id: GO:0050804
      label: modulation of chemical synaptic transmission
  - preferred_term: regulation of membrane potential
    modifier: DYSREGULATED
    term:
      id: GO:0042391
      label: regulation of membrane potential
  downstream:
  - target: Cortical network hyperexcitability with abnormal EEG background
    description: Physiologic instability at synaptic and membrane levels manifests as hyperexcitable cortical activity.
    evidence:
    - reference: PMID:14510623
      reference_title: "Angelman syndrome: etiology, clinical features, diagnosis, and management of symptoms."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Seizures, abnormal electroencephalography, microcephaly, and scoliosis are observed in >80% of patients."
      explanation: Supports transition from excitability dysregulation to abnormal EEG-related network state.
    - reference: PMID:39914145
      reference_title: "UBE3A controls axon initial segment in the cortical pyramidal neurons."
      supports: SUPPORT
      evidence_source: MODEL_ORGANISM
      snippet: "In this study, we compared wild-type mice with three different Ube3a-deficient mice and observed specific elongation of the AIS in the prelimbic cortex of the medial prefrontal cortex but not in the somatosensory cortex or motor cortex, as previously reported."
      explanation: Region-specific AIS structural changes in Ube3a-deficient cortex support cortical excitability-network disturbance.
  evidence:
  - reference: PMID:33543479
    reference_title: "UBE3A reinstatement as a disease-modifying therapy for Angelman syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "It has been consistently shown that mouse models of Angelman syndrome show marked changes in synaptic plasticity and excitatory/inhibitory balance."
    explanation: Supports disrupted excitability homeostasis event.
  - reference: PMID:39914145
    reference_title: "UBE3A controls axon initial segment in the cortical pyramidal neurons."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "The axon initial segment (AIS) is a critical regulator of neuronal excitability and the initiation site of action potentials."
    explanation: Adds direct mechanistic support for excitability-homeostasis framing in cortical neurons.
- name: GABA-A receptor cluster hemizygosity in deletion subtype
  description: >-
    In deletion-type Angelman syndrome, hemizygous loss of the contiguous
    GABRB3-GABRA5-GABRG3 GABA-A receptor subunit cluster compounds neuronal
    UBE3A loss and contributes to a more severe epilepsy and EEG phenotype than
    in non-deletion genotypes.
  genes:
  - preferred_term: GABRB3
    term:
      id: hgnc:4083
      label: GABRB3
  - preferred_term: GABRA5
    term:
      id: hgnc:4079
      label: GABRA5
  - preferred_term: GABRG3
    term:
      id: hgnc:4088
      label: GABRG3
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  locations:
  - preferred_term: cerebral cortex
    term:
      id: UBERON:0000956
      label: cerebral cortex
  downstream:
  - target: Cortical network hyperexcitability with abnormal EEG background
    description: GABA-A receptor cluster hemizygosity exacerbates excitatory/inhibitory imbalance and epileptiform network activity.
    evidence:
    - reference: PMID:30826071
      reference_title: "Electrophysiological Phenotype in Angelman Syndrome Differs Between Genotypes."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "We found elevated theta power (peak frequency: 5.3 Hz) and diminished beta power (peak frequency: 23 Hz) in the deletion genotype compared with the nondeletion genotype as well as excess broadband EEG power (1-32 Hz) peaking in the delta frequency range (peak frequency: 2.8 Hz), shared by both genotypes but stronger for the deletion genotype at younger ages."
      explanation: Genotype-stratified EEG signatures linking GABA-A cluster hemizygosity to a more severe network phenotype.
  evidence:
  - reference: PMID:30826071
    reference_title: "Electrophysiological Phenotype in Angelman Syndrome Differs Between Genotypes."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Angelman syndrome (AS) is a severe neurodevelopmental disorder caused by either disruptions of the gene UBE3A or deletion of chromosome 15 at 15q11-q13, which encompasses UBE3A and several other genes, including GABRB3, GABRA5, GABRG3, encoding gamma-aminobutyric acid type A receptor subunits (β3, α5, γ3)."
    explanation: Establishes the contiguous gene context of deletion AS.
  - reference: PMID:34536900
    reference_title: "Clinical Characterization of Epilepsy in Children With Angelman Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "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."
    explanation: Supports clinically more severe epilepsy phenotype in deletion AS attributable to contiguous gene effects.
- name: OCA2 haploinsufficiency in deletion subtype
  description: >-
    Codeletion of OCA2 in the typical 15q11.2-q13 deletion produces partial
    oculocutaneous albinism features (iris hypopigmentation, severe astigmatism,
    and high myopia) restricted to the deletion subtype.
  genes:
  - preferred_term: OCA2
    term:
      id: hgnc:8101
      label: OCA2
  cell_types:
  - preferred_term: melanocyte
    term:
      id: CL:0000148
      label: melanocyte
  locations:
  - preferred_term: eye
    term:
      id: UBERON:0000970
      label: eye
  downstream:
  - target: Iris hypopigmentation
    description: OCA2 haploinsufficiency reduces ocular pigmentation in deletion-type AS.
    evidence:
    - reference: PMID:41905512
      reference_title: "Ophthalmic phenotype and strabismus surgery in Angelman syndrome: genotype-specific risks and uniform surgical efficacy."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Severe iris hypopigmentation (grades 3-4) was unique to the deletion subgroup (33% vs. 0%; P = 0.013), linked to OCA2 codeletion."
      explanation: Direct support for OCA2-mediated iris hypopigmentation restricted to deletion AS.
  - target: Astigmatism
    description: Reduced melanin during ocular development contributes to refractive abnormality, with high astigmatism enriched in the deletion subgroup.
    evidence:
    - reference: PMID:41905512
      reference_title: "Ophthalmic phenotype and strabismus surgery in Angelman syndrome: genotype-specific risks and uniform surgical efficacy."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "The 15q11.2-q13 deletions confer a distinct oculoalbinism phenotype mediated by OCA2 haploinsufficiency, featuring high myopia, severe astigmatism, and iris hypopigmentation."
      explanation: Directly attributes severe astigmatism to OCA2 haploinsufficiency in deletion AS.
  - target: Myopia
    description: OCA2 haploinsufficiency contributes to high myopia restricted to deletion-type AS.
    evidence:
    - reference: PMID:41905512
      reference_title: "Ophthalmic phenotype and strabismus surgery in Angelman syndrome: genotype-specific risks and uniform surgical efficacy."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "The 15q11.2-q13 deletions confer a distinct oculoalbinism phenotype mediated by OCA2 haploinsufficiency, featuring high myopia, severe astigmatism, and iris hypopigmentation."
      explanation: Directly attributes high myopia to OCA2 haploinsufficiency in deletion AS.
  evidence:
  - reference: PMID:41905512
    reference_title: "Ophthalmic phenotype and strabismus surgery in Angelman syndrome: genotype-specific risks and uniform surgical efficacy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The 15q11.2-q13 deletions confer a distinct oculoalbinism phenotype mediated by OCA2 haploinsufficiency, featuring high myopia, severe astigmatism, and iris hypopigmentation."
    explanation: Defines OCA2 codeletion as the molecular driver of the deletion-specific ophthalmic phenotype.
- name: Cortical network hyperexcitability with abnormal EEG background
  description: >-
    Hyperexcitable cortical networks produce persistent epileptiform liability
    and abnormal electroencephalographic backgrounds.
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  locations:
  - preferred_term: cerebral cortex
    term:
      id: UBERON:0000956
      label: cerebral cortex
  downstream:
  - target: Seizures
    description: Hyperexcitable cortical networks drive recurrent seizure phenotypes.
    evidence:
    - reference: PMID:20398390
      reference_title: "Epilepsy in patients with Angelman syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Epilepsy, often severe and hard to control, is present in 85% of patients within the first three years of life, although less than 25% develop seizures during the first year."
      explanation: Supports high seizure burden as a downstream clinical manifestation.
  - target: Sleep disturbance
    description: Persistent network instability contributes to long-term sleep dysregulation.
    evidence:
    - reference: PMID:25428759
      reference_title: "Angelman syndrome in adulthood."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "While late-adolescent and adult sleep patterns were improved when compared to the degree of sleep dysfunction present during infancy and childhood, the prevalence of poor sleep in adults remained quite high."
      explanation: Supports persistent sleep dysregulation as a downstream neurophysiologic phenotype.
  evidence:
  - reference: PMID:14510623
    reference_title: "Angelman syndrome: etiology, clinical features, diagnosis, and management of symptoms."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Seizures, abnormal electroencephalography, microcephaly, and scoliosis are observed in >80% of patients."
    explanation: Supports coupling of epileptic burden with abnormal EEG background.
  - reference: PMID:29719672
    reference_title: "Abnormal coherence and sleep composition in children with Angelman syndrome: a retrospective EEG study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Individuals with AS display characteristic EEG patterns including high-amplitude rhythmic delta waves."
    explanation: Provides quantitative-EEG description of the abnormal cortical-network background.
  - reference: PMID:35611307
    reference_title: "Longitudinal EEG model detects antisense oligonucleotide treatment effect and increased UBE3A in Angelman syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Delta power measured in the scalp EEG is a reliable biomarker for Angelman syndrome but varies widely across individuals and throughout development, making detection of a treatment effect using single measurements challenging."
    explanation: Establishes elevated EEG delta as a translatable biomarker of cortical network hyperexcitability.
- name: Autonomic and enteric nervous system dysfunction
  description: >-
    UBE3A loss in autonomic and enteric neuronal populations contributes to
    pervasive gastrointestinal dysmotility manifesting as constipation and
    gastroesophageal reflux across the AS lifespan.
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  locations:
  - preferred_term: enteric nervous system
    term:
      id: UBERON:0002005
      label: enteric nervous system
  biological_processes:
  - preferred_term: peristalsis
    modifier: DECREASED
    term:
      id: GO:0030432
      label: peristalsis
  downstream:
  - target: Constipation
    description: Enteric/autonomic dysfunction contributes to chronic constipation in AS.
    evidence:
    - reference: PMID:28816003
      reference_title: "Prevalence of gastrointestinal symptoms in Angelman syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "The majority of patients' medical records indicated at least one symptom of gastrointestinal dysfunction, with constipation and gastroesophageal reflux disease (GERD) the most common."
      explanation: Supports constipation as a major downstream GI manifestation of AS.
  - target: Gastroesophageal reflux
    description: Enteric/autonomic dysfunction with impaired esophageal motility contributes to GERD.
    evidence:
    - reference: PMID:28816003
      reference_title: "Prevalence of gastrointestinal symptoms in Angelman syndrome."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "The majority of patients' medical records indicated at least one symptom of gastrointestinal dysfunction, with constipation and gastroesophageal reflux disease (GERD) the most common."
      explanation: Supports GERD as a major downstream GI manifestation of AS.
  evidence:
  - reference: PMID:28816003
    reference_title: "Prevalence of gastrointestinal symptoms in Angelman syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The majority of patients' medical records indicated at least one symptom of gastrointestinal dysfunction, with constipation and gastroesophageal reflux disease (GERD) the most common."
    explanation: Establishes the high prevalence of GI dysmotility consistent with autonomic/enteric nervous system involvement in AS.
phenotypes:
- name: Severe intellectual disability
  category: Neurodevelopmental
  frequency: VERY_FREQUENT
  diagnostic: true
  phenotype_term:
    preferred_term: Severe intellectual disability
    term:
      id: HP:0010864
      label: Severe intellectual disability
  evidence:
  - reference: PMID:20301323
    reference_title: "Angelman Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Angelman syndrome (AS) is characterized by severe developmental delay or intellectual disability"
    explanation: Supports severe cognitive impairment as a core phenotype.
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0010864 | Intellectual disability, severe | Very frequent (99-80%)"
    explanation: Orphanet phenotype table confirms very frequent (99-80%) severe intellectual disability.
- name: Global developmental delay
  category: Neurodevelopmental
  frequency: VERY_FREQUENT
  diagnostic: true
  phenotype_term:
    preferred_term: Global developmental delay
    term:
      id: HP:0001263
      label: Global developmental delay
  evidence:
  - reference: PMID:14510623
    reference_title: "Angelman syndrome: etiology, clinical features, diagnosis, and management of symptoms."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Clinical findings present in all patients include developmental delay, which becomes apparent by 6-12 months of age"
    explanation: Supports near-universal developmental delay and its timing.
- name: Severe speech impairment
  category: Neurodevelopmental
  frequency: VERY_FREQUENT
  diagnostic: true
  phenotype_term:
    preferred_term: Severe expressive speech impairment
    term:
      id: HP:0002465
      label: Poor speech
  evidence:
  - reference: PMID:14510623
    reference_title: "Angelman syndrome: etiology, clinical features, diagnosis, and management of symptoms."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Clinical findings present in all patients include developmental delay, which becomes apparent by 6-12 months of age, severely impaired expressive language"
    explanation: Supports severe expressive language impairment as a defining feature.
- name: Gait ataxia
  category: Neurological
  frequency: VERY_FREQUENT
  diagnostic: true
  phenotype_term:
    preferred_term: Gait ataxia
    term:
      id: HP:0002066
      label: Gait ataxia
  evidence:
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001251 | Ataxia | Very frequent (99-80%)"
    explanation: Orphanet phenotype table confirms very frequent (99-80%) ataxia; gait ataxia is a child term.
  - reference: PMID:20301323
    reference_title: "Angelman Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Angelman syndrome (AS) is characterized by severe developmental delay or intellectual disability, severe speech impairment, gait ataxia and/or tremulousness of the limbs"
    explanation: Supports ataxic gait as a cardinal motor phenotype.
- name: Seizures
  category: Neurological
  frequency: VERY_FREQUENT
  diagnostic: true
  phenotype_term:
    preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  evidence:
  - reference: PMID:20398390
    reference_title: "Epilepsy in patients with Angelman syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Epilepsy, often severe and hard to control, is present in 85% of patients within the first three years of life, although less than 25% develop seizures during the first year."
    explanation: Quantifies high seizure prevalence and early onset.
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001250 | Seizure | Very frequent (99-80%)"
    explanation: Orphanet phenotype table confirms very frequent (99-80%) seizures.
- name: Sleep disturbance
  category: Neurological
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Sleep disturbance
    term:
      id: HP:0002360
      label: Sleep disturbance
  evidence:
  - reference: PMID:24876791
    reference_title: "Angelman syndrome: review of clinical and molecular aspects."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The behavioral features of AS include a happy demeanor, easily provoked laughter, short attention span, hypermotoric behavior, mouthing of objects, sleep disturbance, and an affinity for water."
    explanation: Supports sleep disturbance as a recurring syndrome feature.
- name: Microcephaly
  category: Neurological
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Microcephaly
    term:
      id: HP:0000252
      label: Microcephaly
  evidence:
  - reference: PMID:14510623
    reference_title: "Angelman syndrome: etiology, clinical features, diagnosis, and management of symptoms."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Seizures, abnormal electroencephalography, microcephaly, and scoliosis are observed in >80% of patients."
    explanation: Supports very high prevalence of microcephaly.
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000252 | Microcephaly | Very frequent (99-80%)"
    explanation: Orphanet phenotype table confirms very frequent (99-80%) microcephaly.
- name: Hyperactivity
  category: Behavioral
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Hyperactivity
    term:
      id: HP:0000752
      label: Hyperactivity
  evidence:
  - reference: PMID:14510623
    reference_title: "Angelman syndrome: etiology, clinical features, diagnosis, and management of symptoms."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Clinical findings present in all patients include developmental delay, which becomes apparent by 6-12 months of age, severely impaired expressive language, ataxic gait, tremulousness of limbs, and a typical behavioral profile, including a happy demeanor, hypermotoric behavior, and low attention span."
    explanation: Supports hypermotor/hyperactive behavioral phenotype.
- name: Inappropriate laughter
  category: Behavioral
  frequency: VERY_FREQUENT
  diagnostic: true
  phenotype_term:
    preferred_term: Inappropriate laughter
    term:
      id: HP:0000748
      label: Inappropriate laughter
  evidence:
  - reference: PMID:20398390
    reference_title: "Epilepsy in patients with Angelman syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Angelman syndrome (AS) is a neuro-behavioural, genetically determined condition, characterized by ataxic jerky movements, happy sociable disposition and unprovoked bouts of laughter in association with seizures, learning disabilities and language impairment."
    explanation: Supports characteristic laughter/happy demeanor phenotype.
- name: Constipation
  category: Gastrointestinal
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Constipation
    term:
      id: HP:0002019
      label: Constipation
  evidence:
  - reference: PMID:28816003
    reference_title: "Prevalence of gastrointestinal symptoms in Angelman syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The majority of patients' medical records indicated at least one symptom of gastrointestinal dysfunction, with constipation and gastroesophageal reflux disease (GERD) the most common."
    explanation: Supports constipation as one of the most prevalent GI comorbidities.
- name: Gastroesophageal reflux
  category: Gastrointestinal
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Gastroesophageal reflux
    term:
      id: HP:0002020
      label: Gastroesophageal reflux
  evidence:
  - reference: PMID:28816003
    reference_title: "Prevalence of gastrointestinal symptoms in Angelman syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The majority of patients' medical records indicated at least one symptom of gastrointestinal dysfunction, with constipation and gastroesophageal reflux disease (GERD) the most common."
    explanation: Supports GERD as a major GI phenotype in AS.
- name: Scoliosis
  category: Musculoskeletal
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Scoliosis
    term:
      id: HP:0002650
      label: Scoliosis
  evidence:
  - reference: PMID:14510623
    reference_title: "Angelman syndrome: etiology, clinical features, diagnosis, and management of symptoms."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Seizures, abnormal electroencephalography, microcephaly, and scoliosis are observed in >80% of patients."
    explanation: Supports scoliosis as a common and clinically relevant musculoskeletal manifestation.
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002650 | Scoliosis | Frequent (79-30%)"
    explanation: Orphanet phenotype table rates scoliosis as frequent (79-30%).
- name: Tremor
  category: Neurological
  phenotype_term:
    preferred_term: Tremor of the limbs
    term:
      id: HP:0001337
      label: Tremor
  evidence:
  - reference: PMID:20301323
    reference_title: "Angelman Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Angelman syndrome (AS) is characterized by severe developmental delay or intellectual disability, severe speech impairment, gait ataxia and/or tremulousness of the limbs"
    explanation: Supports limb tremor/tremulousness as part of the cardinal motor profile.
- name: Strabismus
  category: Ophthalmologic
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Strabismus
    term:
      id: HP:0000486
      label: Strabismus
  evidence:
  - reference: PMID:41905512
    reference_title: "Ophthalmic phenotype and strabismus surgery in Angelman syndrome: genotype-specific risks and uniform surgical efficacy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Ophthalmic manifestations in Angelman syndrome (AS)-particularly strabismus surgical outcomes and genotype-phenotype correlations-remain inadequately characterized due to limited cohort sizes in prior studies."
    explanation: Documents strabismus as a clinically significant ophthalmic manifestation requiring surgical correction in AS.
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000486 | Strabismus | Frequent (79-30%)"
    explanation: Orphanet phenotype table confirms frequent (79-30%) strabismus.
- name: Iris hypopigmentation
  category: Ophthalmologic
  subtype: Maternal 15q11.2-q13 deletion Angelman syndrome
  phenotype_term:
    preferred_term: Iris hypopigmentation
    term:
      id: HP:0007730
      label: Iris hypopigmentation
  evidence:
  - reference: PMID:41905512
    reference_title: "Ophthalmic phenotype and strabismus surgery in Angelman syndrome: genotype-specific risks and uniform surgical efficacy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Severe iris hypopigmentation (grades 3-4) was unique to the deletion subgroup (33% vs. 0%; P = 0.013), linked to OCA2 codeletion."
    explanation: Restricts iris hypopigmentation to the deletion subtype, mediated by OCA2 codeletion.
- name: Astigmatism
  category: Ophthalmologic
  subtype: Maternal 15q11.2-q13 deletion Angelman syndrome
  phenotype_term:
    preferred_term: Astigmatism
    term:
      id: HP:0000483
      label: Astigmatism
  evidence:
  - reference: PMID:41905512
    reference_title: "Ophthalmic phenotype and strabismus surgery in Angelman syndrome: genotype-specific risks and uniform surgical efficacy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "High astigmatism (≥2.00 DC) was significantly more prevalent in deletion patients (54% vs 19% [P = 0.004])."
    explanation: Quantifies the deletion-genotype-specific astigmatism risk.
- name: Myopia
  category: Ophthalmologic
  subtype: Maternal 15q11.2-q13 deletion Angelman syndrome
  phenotype_term:
    preferred_term: High myopia
    term:
      id: HP:0000545
      label: Myopia
  evidence:
  - reference: PMID:41905512
    reference_title: "Ophthalmic phenotype and strabismus surgery in Angelman syndrome: genotype-specific risks and uniform surgical efficacy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "High myopia (> -6.00 D) occurred exclusively in deletion patients (n = 2)."
    explanation: Documents the deletion-restricted high-myopia phenotype.
- name: EEG abnormality
  category: Neurological
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: EEG abnormality
    term:
      id: HP:0002353
      label: EEG abnormality
  evidence:
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002353 | EEG abnormality | Very frequent (99-80%)"
    explanation: Orphanet phenotype table rates EEG abnormality as very frequent (99-80%).
  - reference: PMID:14510623
    reference_title: "Angelman syndrome: etiology, clinical features, diagnosis, and management of symptoms."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Seizures, abnormal electroencephalography, microcephaly, and scoliosis are observed in >80% of patients."
    explanation: Supports very high prevalence of abnormal EEG.
- name: Cerebral cortical atrophy
  category: Neurological
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Cerebral cortical atrophy
    term:
      id: HP:0002120
      label: Cerebral cortical atrophy
  evidence:
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002120 | Cerebral cortical atrophy | Very frequent (99-80%)"
    explanation: Orphanet phenotype table rates cerebral cortical atrophy as very frequent (99-80%).
- name: Broad-based gait
  category: Neurological
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Broad-based gait
    term:
      id: HP:0002136
      label: Broad-based gait
  evidence:
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002136 | Broad-based gait | Very frequent (99-80%)"
    explanation: Orphanet phenotype table rates broad-based gait as very frequent (99-80%).
- name: Motor delay
  category: Neurodevelopmental
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Motor delay
    term:
      id: HP:0001270
      label: Motor delay
  evidence:
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001270 | Motor delay | Very frequent (99-80%)"
    explanation: Orphanet phenotype table rates motor delay as very frequent (99-80%).
- name: Autistic behavior
  category: Behavioral
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Autistic behavior
    term:
      id: HP:0000729
      label: Autistic behavior
  evidence:
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000729 | Autistic behavior | Very frequent (99-80%)"
    explanation: Orphanet phenotype table rates autistic behavior as very frequent (99-80%).
- name: Self-injurious behavior
  category: Behavioral
  frequency: VERY_FREQUENT
  phenotype_term:
    preferred_term: Self-injurious behavior
    term:
      id: HP:0100716
      label: Self-injurious behavior
  evidence:
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0100716 | Self-injurious behavior | Very frequent (99-80%)"
    explanation: Orphanet phenotype table rates self-injurious behavior as very frequent (99-80%).
- name: Obesity
  category: Metabolic
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Obesity
    term:
      id: HP:0001513
      label: Obesity
  evidence:
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001513 | Obesity | Frequent (79-30%)"
    explanation: Orphanet phenotype table rates obesity as frequent (79-30%).
- name: Drooling
  category: Orofacial
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Drooling
    term:
      id: HP:0002307
      label: Drooling
  evidence:
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002307 | Drooling | Frequent (79-30%)"
    explanation: Orphanet phenotype table rates drooling as frequent (79-30%).
- name: Feeding difficulties
  category: Gastrointestinal
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Feeding difficulties
    term:
      id: HP:0011968
      label: Feeding difficulties
  evidence:
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0011968 | Feeding difficulties | Frequent (79-30%)"
    explanation: Orphanet phenotype table rates feeding difficulties as frequent (79-30%).
- name: Wide mouth
  category: Craniofacial
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Wide mouth
    term:
      id: HP:0000154
      label: Wide mouth
  evidence:
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0000154 | Wide mouth | Frequent (79-30%)"
    explanation: Orphanet phenotype table rates wide mouth as frequent (79-30%).
- name: Protruding tongue
  category: Craniofacial
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Protruding tongue
    term:
      id: HP:0010808
      label: Protruding tongue
  evidence:
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0010808 | Protruding tongue | Frequent (79-30%)"
    explanation: Orphanet phenotype table rates protruding tongue as frequent (79-30%).
- name: Hypopigmentation of the skin
  category: Dermatologic
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Hypopigmentation of the skin
    term:
      id: HP:0001010
      label: Hypopigmentation of the skin
  evidence:
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0001010 | Hypopigmentation of the skin | Frequent (79-30%)"
    explanation: Orphanet phenotype table rates skin hypopigmentation as frequent (79-30%).
- name: Recurrent hand flapping
  category: Behavioral
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Recurrent hand flapping
    term:
      id: HP:0100023
      label: Recurrent hand flapping
  evidence:
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0100023 | Recurrent hand flapping | Frequent (79-30%)"
    explanation: Orphanet phenotype table rates recurrent hand flapping as frequent (79-30%).
- name: Fair hair
  category: Dermatologic
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Fair hair
    term:
      id: HP:0002286
      label: Fair hair
  evidence:
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002286 | Fair hair | Frequent (79-30%)"
    explanation: Orphanet phenotype table rates fair hair as frequent (79-30%).
- name: Polyphagia
  category: Behavioral
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Polyphagia
    term:
      id: HP:0002591
      label: Polyphagia
  evidence:
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0002591 | Polyphagia | Frequent (79-30%)"
    explanation: Orphanet phenotype table rates polyphagia as frequent (79-30%).
- name: Infantile hypotonia
  category: Neurological
  frequency: FREQUENT
  phenotype_term:
    preferred_term: Infantile hypotonia
    term:
      id: HP:0008947
      label: Floppy infant
  evidence:
  - reference: ORPHA:72
    reference_title: "Angelman syndrome (Orphanet structured-database record)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "HP:0008947 | Floppy infant | Frequent (79-30%)"
    explanation: Orphanet phenotype table rates infantile hypotonia as frequent (79-30%).
genetic:
- name: UBE3A
  gene_term:
    preferred_term: UBE3A
    term:
      id: hgnc:12496
      label: UBE3A
  association: Causative
  notes: >-
    Loss of maternally inherited UBE3A function in neurons is the central
    genetic mechanism across molecular classes.
  evidence:
  - reference: PMID:33543479
    reference_title: "UBE3A reinstatement as a disease-modifying therapy for Angelman syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Angelman syndrome is caused by mutations affecting the maternally inherited UBE3A gene, which encodes an E3-ubiquitin ligase that is critical for typical postnatal brain development."
    explanation: Supports UBE3A as the primary disease gene.
  - reference: CGGV:assertion_df25de82-ea9a-4d86-8b42-6587a39650e3-2018-05-02T132344.716Z
    reference_title: "UBE3A / Angelman syndrome (Definitive)"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "UBE3A | HGNC:12496 | Angelman syndrome | MONDO:0007113 | AD | Definitive"
    explanation: ClinGen classifies the UBE3A-Angelman syndrome gene-disease relationship as definitive with autosomal dominant inheritance.
- name: 15q11.2-q13 maternal deletion and imprinting-region abnormalities
  association: Major molecular classes
  notes: >-
    Large maternal deletions, paternal UPD, and imprinting defects account for
    most non-UBE3A-variant cases.
  evidence:
  - reference: PMID:20301323
    reference_title: "Angelman Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Analysis of parent-specific DNA methylation imprints in the 15q11.2-q13 chromosome region detects approximately 80% of individuals with AS, including those with a deletion, uniparental disomy, or an imprinting defect"
    explanation: Supports the major non-sequence molecular mechanisms.
- name: GABRB3
  gene_term:
    preferred_term: GABRB3
    term:
      id: hgnc:4083
      label: GABRB3
  association: Modifier (deletion subtype)
  notes: >-
    Codeleted with UBE3A in typical 15q11.2-q13 deletions; hemizygosity contributes
    to a more severe epilepsy and EEG phenotype in the deletion subtype.
  evidence:
  - reference: PMID:30826071
    reference_title: "Electrophysiological Phenotype in Angelman Syndrome Differs Between Genotypes."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "deletion of chromosome 15 at 15q11-q13, which encompasses UBE3A and several other genes, including GABRB3, GABRA5, GABRG3, encoding gamma-aminobutyric acid type A receptor subunits (β3, α5, γ3)."
    explanation: Documents codeletion of GABRB3 with UBE3A in deletion-genotype AS.
- name: GABRA5
  gene_term:
    preferred_term: GABRA5
    term:
      id: hgnc:4079
      label: GABRA5
  association: Modifier (deletion subtype)
  notes: >-
    Member of the GABRB3-GABRA5-GABRG3 cluster codeleted in typical 15q11.2-q13
    deletion AS; hemizygosity proposed to contribute to deletion-specific
    pathophysiology.
  evidence:
  - reference: PMID:30826071
    reference_title: "Electrophysiological Phenotype in Angelman Syndrome Differs Between Genotypes."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "hemizygosity of the GABRB3-GABRA5-GABRG3 gene cluster causes abnormal theta and beta EEG oscillations that may underlie the more severe clinical phenotype."
    explanation: Provides direct evidence for GABRA5 cluster hemizygosity contributing to deletion-AS pathophysiology.
- name: GABRG3
  gene_term:
    preferred_term: GABRG3
    term:
      id: hgnc:4088
      label: GABRG3
  association: Modifier (deletion subtype)
  notes: >-
    Third member of the GABA-A receptor subunit cluster codeleted in typical
    15q11.2-q13 deletion AS.
  evidence:
  - reference: PMID:30826071
    reference_title: "Electrophysiological Phenotype in Angelman Syndrome Differs Between Genotypes."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "hemizygosity of the GABRB3-GABRA5-GABRG3 gene cluster causes abnormal theta and beta EEG oscillations that may underlie the more severe clinical phenotype."
    explanation: Supports GABRG3 cluster hemizygosity as part of the deletion-AS modifier locus.
- name: OCA2
  gene_term:
    preferred_term: OCA2
    term:
      id: hgnc:8101
      label: OCA2
  association: Modifier (deletion subtype)
  notes: >-
    Codeletion of OCA2 in typical 15q11.2-q13 deletions causes the
    deletion-restricted oculocutaneous albinism-like ophthalmic phenotype
    (iris hypopigmentation, severe astigmatism, and high myopia).
  evidence:
  - reference: PMID:41905512
    reference_title: "Ophthalmic phenotype and strabismus surgery in Angelman syndrome: genotype-specific risks and uniform surgical efficacy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The 15q11.2-q13 deletions confer a distinct oculoalbinism phenotype mediated by OCA2 haploinsufficiency, featuring high myopia, severe astigmatism, and iris hypopigmentation."
    explanation: Identifies OCA2 codeletion as the molecular basis for the deletion-specific ophthalmic phenotype.
diagnosis:
- name: Parent-specific DNA methylation analysis of 15q11.2-q13
  diagnosis_term:
    preferred_term: diagnostic procedure
    term:
      id: MAXO:0000003
      label: diagnostic procedure
  description: First-line molecular test in suspected Angelman syndrome.
  results: Detects most cases due to deletion, UPD, or imprinting defect.
  evidence:
  - reference: PMID:20301323
    reference_title: "Angelman Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Analysis of parent-specific DNA methylation imprints in the 15q11.2-q13 chromosome region detects approximately 80% of individuals with AS, including those with a deletion, uniparental disomy, or an imprinting defect"
    explanation: Supports methylation analysis as primary diagnostic assay.
- name: UBE3A sequence analysis
  diagnosis_term:
    preferred_term: diagnostic procedure
    term:
      id: MAXO:0000003
      label: diagnostic procedure
  description: Reflex molecular testing when methylation study is negative.
  results: Adds diagnostic yield for UBE3A pathogenic variants.
  evidence:
  - reference: PMID:20301323
    reference_title: "Angelman Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "UBE3A sequence analysis detects pathogenic variants in an additional approximately 11% of individuals."
    explanation: Supports reflex sequencing after negative methylation testing.
- name: Consensus clinical diagnostic criteria assessment
  diagnosis_term:
    preferred_term: diagnostic procedure
    term:
      id: MAXO:0000003
      label: diagnostic procedure
  description: Clinical phenotype evaluation remains central, particularly in molecularly unresolved cases.
  evidence:
  - reference: PMID:20301323
    reference_title: "Angelman Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The diagnosis of AS is established in a proband who meets the consensus clinical diagnostic criteria and/or who has findings on molecular genetic testing that suggest deficient expression or function of the maternally inherited UBE3A allele."
    explanation: Supports integrated clinical-plus-molecular diagnosis.
- name: Electroencephalographic supportive testing
  diagnosis_term:
    preferred_term: diagnostic procedure
    term:
      id: MAXO:0000003
      label: diagnostic procedure
  description: EEG abnormalities are supportive but not fully specific.
  evidence:
  - reference: PMID:20398390
    reference_title: "Epilepsy in patients with Angelman syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The EEG abnormalities are not themselves pathognomonic of AS and both background activity and epileptic discharges vary even in the same patient with time."
    explanation: Supports EEG as a supportive, non-pathognomonic diagnostic adjunct.
- name: Quantitative EEG (qEEG) as biomarker
  diagnosis_term:
    preferred_term: diagnostic procedure
    term:
      id: MAXO:0000003
      label: diagnostic procedure
  description: >-
    Quantitative EEG features (elevated absolute and relative delta power,
    altered coherence, reduced sleep spindles, genotype-specific spectral
    differences) provide objective biomarkers of network pathology and are being
    used in disease-modifying trials to demonstrate target engagement.
  results: >-
    Elevated broadband delta power, reduced sleep spindles, and increased
    long-range coherence; deletion-genotype-specific theta excess and beta
    deficit.
  evidence:
  - reference: PMID:29719672
    reference_title: "Abnormal coherence and sleep composition in children with Angelman syndrome: a retrospective EEG study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We demonstrate two quantitative readouts of dysregulated sleep composition in children with AS-gamma coherence and spindles-and describe how functional connectivity patterns may be disrupted during wakefulness."
    explanation: Establishes quantitative EEG features as candidate biomarkers in AS.
  - reference: PMID:30826071
    reference_title: "Electrophysiological Phenotype in Angelman Syndrome Differs Between Genotypes."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We found elevated theta power (peak frequency: 5.3 Hz) and diminished beta power (peak frequency: 23 Hz) in the deletion genotype compared with the nondeletion genotype as well as excess broadband EEG power (1-32 Hz) peaking in the delta frequency range (peak frequency: 2.8 Hz), shared by both genotypes but stronger for the deletion genotype at younger ages."
    explanation: Genotype-stratified spectral signatures supporting qEEG as a diagnostic-stratification tool.
  - reference: PMID:35611307
    reference_title: "Longitudinal EEG model detects antisense oligonucleotide treatment effect and increased UBE3A in Angelman syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Deviations in delta power from a human natural history model in Angelman syndrome can detect antisense oligonucleotide-mediated improvement in Ube3a expression in Angelman syndrome mice and may be relevant for human clinical trials."
    explanation: Supports longitudinal qEEG modeling as a translational biomarker for ASO trials.
  - reference: PMID:33203220
    reference_title: "Quantitative EEG Analysis in Angelman Syndrome: Candidate Method for Assessing Therapeutics."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Our findings support the use of qEEG analysis in evaluating AS and suggest that this technique may be useful to evaluate therapeutic efficacy in AS."
    explanation: Establishes qEEG as a methodological framework for therapeutic assessment in AS.
treatments:
- name: Combination anti-seizure pharmacotherapy
  description: >-
    Seizure control is frequently achieved with combination anti-seizure
    medication regimens, with a newer-agent-forward approach for tolerability.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: levetiracetam
      term:
        id: CHEBI:6437
        label: levetiracetam
    - preferred_term: lamotrigine
      term:
        id: CHEBI:6367
        label: lamotrigine
    - preferred_term: clobazam
      term:
        id: CHEBI:31413
        label: clobazam
    - preferred_term: valproic acid
      term:
        id: CHEBI:39867
        label: valproic acid
  target_phenotypes:
  - preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  evidence:
  - reference: PMID:27206232
    reference_title: "Seizure treatment in Angelman syndrome: A case series from the Angelman Syndrome Clinic at Massachusetts General Hospital."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Newer antiepileptic drugs such as levetiracetam, lamotrigine, and clobazam, and to a lesser extent topiramate, appeared to be as effective - if not more so - as valproic acid and clonazepam while offering more favorable side effect profiles."
    explanation: Supports use of specific newer ASMs with improved tolerability in Angelman syndrome.
  - reference: PMID:35862628
    reference_title: "Pharmacotherapeutic management of seizures in patients with Angleman Syndrome."
    supports: PARTIAL
    evidence_source: OTHER
    snippet: "Evidence for treating seizures in AS mainly derives from low-quality studies. Levetiracetam and clobazam are the most commonly used ASMs."
    explanation: Adds review-level context on current ASM usage patterns and evidence limitations.
  - reference: PMID:20301323
    reference_title: "Angelman Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Treatment of manifestations: Anti-seizure medication for seizures."
    explanation: Direct management recommendation for epilepsy in AS.
  target_mechanisms:
  - target: Disrupted neuronal excitability homeostasis
    treatment_effect: INHIBITS
    description: >-
      Anti-seizure medications (levetiracetam, clobazam, valproate, lamotrigine)
      suppress pathological hyperexcitability arising from reduced UBE3A-dependent
      regulation of neuronal firing thresholds.
  - target: Cortical network hyperexcitability with abnormal EEG background
    treatment_effect: INHIBITS
    description: >-
      ASM combination regimens reduce cortical seizure activity and improve the
      characteristic high-amplitude delta-band EEG background seen in Angelman
      syndrome.
- name: Highly purified cannabidiol for refractory epilepsy
  description: >-
    Highly purified cannabidiol is being used for refractory epilepsy
    associated with 15q11.2-q13 deletion (Angelman syndrome) and duplication
    syndromes; real-world data show meaningful seizure reduction and adjunctive
    behavioral/sleep benefits with good tolerability.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: cannabidiol
      term:
        id: CHEBI:69478
        label: cannabidiol
  target_phenotypes:
  - preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  - preferred_term: Sleep disturbance
    term:
      id: HP:0002360
      label: Sleep disturbance
  evidence:
  - reference: PMID:41992447
    reference_title: "Real-world effectiveness of highly purified cannabidiol in epilepsy associated with 15q11.2-q13.1 duplication and deletion syndromes: A multicenter study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "At last observation, mean seizure reduction was 55.7% (95% confidence interval 38.7-72.7), with 63.6% patients achieving ≥50% reduction, 40.9% achieving ≥75% reduction, and 18.2% achieving seizure freedom."
    explanation: Quantifies real-world seizure reduction with highly purified CBD in 15q-DDS including Angelman syndrome.
  - reference: PMID:41992447
    reference_title: "Real-world effectiveness of highly purified cannabidiol in epilepsy associated with 15q11.2-q13.1 duplication and deletion syndromes: A multicenter study."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "Tonic seizures in dup15q and myoclonic seizures in AS showed the most notable reductions."
    explanation: Suggests subtype-specific seizure-type response patterns in AS treated with CBD.
  - reference: PMID:41992447
    reference_title: "Real-world effectiveness of highly purified cannabidiol in epilepsy associated with 15q11.2-q13.1 duplication and deletion syndromes: A multicenter study."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "CBD was well tolerated; no patient discontinued CBD due to side effects alone, and retention at last visit was 81.8%."
    explanation: Supports tolerability of CBD treatment in AS.
  target_mechanisms:
  - target: Disrupted neuronal excitability homeostasis
    treatment_effect: INHIBITS
    description: >-
      Cannabidiol modulates neuronal excitability through multiple mechanisms
      including TRPV1 and GPR55 receptor activity, suppressing refractory
      myoclonic seizures in the UBE3A-deficient cortical network.
  - target: Cortical network hyperexcitability with abnormal EEG background
    treatment_effect: INHIBITS
    description: >-
      CBD significantly reduces seizure frequency in refractory AS-associated
      epilepsy, with particular efficacy against myoclonic seizure types.
- name: Strabismus surgery
  description: >-
    Standardized strabismus surgery (extraocular-muscle surgery) achieves
    stable ocular alignment in Angelman syndrome regardless of molecular
    subtype, with high success rates and minimal need for reoperation.
  treatment_term:
    preferred_term: extraocular muscle surgery for strabismus
    term:
      id: MAXO:0000004
      label: surgical procedure
  target_phenotypes:
  - preferred_term: Strabismus
    term:
      id: HP:0000486
      label: Strabismus
  evidence:
  - reference: PMID:41905512
    reference_title: "Ophthalmic phenotype and strabismus surgery in Angelman syndrome: genotype-specific risks and uniform surgical efficacy."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Surgical success (exodeviation ≤8Δ/esodeviation ≤5Δ at 1 year) was comparable (70% vs 77%; P > 0.05), with minimal exodrift (deletion, -14.9Δ; nondeletion, -12.3Δ) and no reoperations."
    explanation: Supports strabismus surgery as an effective intervention with comparable success across AS molecular subtypes.
- name: Low-glycemic-index dietary therapy
  description: >-
    Low-glycemic-index dietary intervention is used as an adjunctive
    non-pharmacologic seizure-management strategy, with mixed efficacy signals
    but good tolerability.
  treatment_term:
    preferred_term: dietary intervention
    term:
      id: MAXO:0000088
      label: dietary intervention
  target_phenotypes:
  - preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  - preferred_term: Sleep disturbance
    term:
      id: HP:0002360
      label: Sleep disturbance
  evidence:
  - reference: PMID:27206232
    reference_title: "Seizure treatment in Angelman syndrome: A case series from the Angelman Syndrome Clinic at Massachusetts General Hospital."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The low glycemic index treatment also provided effective seizure control with minimal side effects."
    explanation: Supports LGIT as an adjunctive dietary option for seizure control.
  - reference: PMID:41121232
    reference_title: "Efficacy and tolerability of a low-glycemic-index ketogenic diet in Angelman syndrome: findings from the DIANE study."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "INTERPRETATION: While the LGID was well-tolerated and showed trends toward neurocognitive and seizure improvements, results were not statistically significant."
    explanation: Adds contemporary prospective evidence showing tolerability with non-significant efficacy trends.
  target_mechanisms:
  - target: Disrupted neuronal excitability homeostasis
    treatment_effect: MODULATES
    description: >-
      Low-glycemic-index dietary therapy stabilizes blood glucose and insulin
      signaling, reducing metabolic contributions to cortical excitability in
      Angelman syndrome.
- name: Tonsillectomy with enhanced postoperative monitoring
  description: >-
    Tonsillectomy is used in selected Angelman patients with sleep-disordered
    breathing or sialorrhea, and should be paired with structured postoperative
    respiratory, pain, and feeding monitoring.
  treatment_term:
    preferred_term: tonsillectomy
    term:
      id: MAXO:0001081
      label: tonsillectomy
  target_phenotypes:
  - preferred_term: Sleep apnea
    term:
      id: HP:0010535
      label: Sleep apnea
  - preferred_term: Sialorrhea
    term:
      id: HP:0002307
      label: Drooling
  evidence:
  - reference: PMID:40776598
    reference_title: "Outcomes After Tonsillectomy in Children With Angelman Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Twelve children with Angelman syndrome underwent tonsillectomy: 7 for sleep-disordered breathing, 4 for sialorrhea, and 1 for recurrent tonsillitis."
    explanation: Supports procedure-level use of tonsillectomy for specific clinical indications in Angelman syndrome.
  - reference: PMID:40776598
    reference_title: "Outcomes After Tonsillectomy in Children With Angelman Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Nine (75.0%) children experienced postoperative complications, most frequently pooling of secretions and oxygen desaturations."
    explanation: Supports need for enhanced perioperative and postoperative monitoring after tonsillectomy.
- name: Physical therapy
  description: Physical therapy is used to improve mobility and support motor function.
  treatment_term:
    preferred_term: physical therapy
    term:
      id: MAXO:0000011
      label: physical therapy
  target_phenotypes:
  - preferred_term: Gait ataxia
    term:
      id: HP:0002066
      label: Gait ataxia
  evidence:
  - reference: PMID:20301323
    reference_title: "Angelman Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Physical therapy, occupational therapy, and speech therapy with an emphasis on nonverbal methods of communication, including augmentative communication aids (e.g., picture cards, communication boards) and signing."
    explanation: Supports standard multidisciplinary rehabilitative care.
- name: Occupational therapy
  description: Occupational therapy supports adaptive daily living and motor planning.
  treatment_term:
    preferred_term: occupational therapy
    term:
      id: MAXO:0001351
      label: occupational therapy
  evidence:
  - reference: PMID:20301323
    reference_title: "Angelman Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Physical therapy, occupational therapy, and speech therapy with an emphasis on nonverbal methods of communication, including augmentative communication aids (e.g., picture cards, communication boards) and signing."
    explanation: Supports occupational therapy as part of standard multidisciplinary care.
- name: Speech therapy and augmentative communication
  description: Speech therapy with nonverbal augmentative strategies is recommended due to severe expressive language deficits.
  treatment_term:
    preferred_term: speech therapy
    term:
      id: MAXO:0000930
      label: speech therapy
  target_phenotypes:
  - preferred_term: Severe expressive speech impairment
    term:
      id: HP:0002465
      label: Poor speech
  evidence:
  - reference: PMID:20301323
    reference_title: "Angelman Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Physical therapy, occupational therapy, and speech therapy with an emphasis on nonverbal methods of communication, including augmentative communication aids (e.g., picture cards, communication boards) and signing."
    explanation: Supports speech-language intervention tailored to severe expressive impairment.
- name: Structured management of gastrointestinal comorbidities
  description: Ongoing management of reflux, feeding, and constipation is recommended.
  treatment_term:
    preferred_term: supportive care
    term:
      id: MAXO:0000950
      label: supportive care
  target_phenotypes:
  - preferred_term: Constipation
    term:
      id: HP:0002019
      label: Constipation
  - preferred_term: Gastroesophageal reflux
    term:
      id: HP:0002020
      label: Gastroesophageal reflux
  evidence:
  - reference: PMID:20301323
    reference_title: "Angelman Syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Routine management of gastroesophageal reflux, feeding difficulties, constipation, and strabismus."
    explanation: Supports routine GI-focused symptomatic management.
differential_diagnoses:
- name: Prader-Willi syndrome
  disease_term:
    preferred_term: Prader-Willi syndrome
    term:
      id: MONDO:0008300
      label: Prader-Willi syndrome
  description: >-
    Prader-Willi syndrome shares the same imprinted chromosomal region and is a
    key laboratory differential during molecular workup.
  evidence:
  - reference: PMID:31235867
    reference_title: "Update of the EMQN/ACGS best practice guidelines for molecular analysis of Prader-Willi and Angelman syndromes."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This article is an update of the best practice guidelines for the molecular analysis of Prader-Willi and Angelman syndromes"
    explanation: Supports direct diagnostic differentiation at the molecular testing level.
- name: HERC2-related Angelman-like neurodevelopmental disorder
  disease_term:
    preferred_term: HERC2-related Angelman-like neurodevelopmental disorder
    term:
      id: MONDO:0014224
      label: developmental delay with autism spectrum disorder and gait instability
  description: >-
    HERC2-related disorders can mimic major Angelman features and should be
    considered in Angelman-like presentations without canonical molecular causes.
  evidence:
  - reference: PMID:33543479
    reference_title: "UBE3A reinstatement as a disease-modifying therapy for Angelman syndrome."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "For instance, patients with a HERC2 mutation share many clinical features with those who have Angelman syndrome."
    explanation: Supports HERC2 disorder as a clinically relevant differential.
- name: Houge-Janssens syndrome
  disease_term:
    preferred_term: Houge-Janssens syndrome
    term:
      id: MONDO:0957553
      label: Houge-Janssens syndrome
  description: >-
    Houge-Janssens syndrome can overlap clinically with Angelman syndrome through
    early neurodevelopmental delay, severe language involvement, seizure risk, and
    behavioral phenotypes.
  distinguishing_features:
  - Houge-Janssens syndrome is PP2A-subunit related (PPP2R5D, PPP2R1A, PPP2CA, PPP2R5C) rather than UBE3A-imprinting related.
  - Angelman syndrome is diagnosed through 15q11.2-q13 methylation/UBE3A testing, whereas Houge-Janssens diagnosis relies on PP2A-gene variant identification.
  evidence:
  - reference: PMID:40555839
    reference_title: "Houge-Janssens syndrome."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The core features are neurodevelopmental delay, especially concerning language, prolonged hypotonia, high risk of seizures, and behavior problems."
    explanation: Supports key symptomatic overlap that makes Houge-Janssens syndrome a relevant clinical differential.
datasets:
- accession: geo:GSE120225
  title: Channelopathy pathogenesis in a human neural cell model of Angelman Syndrome
  description: >-
    RNA-seq dataset from human induced neurons and 3D cortical organoids derived
    from Angelman patient iPSCs and UBE3A-knockout hESC lines, used to study
    network hyperexcitability mechanisms.
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  data_type: BULK_RNA_SEQ
  sample_count: 6
  conditions:
  - Angelman syndrome iPSC-derived neural model
  - UBE3A-knockout hESC-derived neural model
  - control neural model
  evidence:
  - reference: GEO:GSE120225
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "Here, by utilizing human induced neurons and 3D cortical organoids derived from AS patient iPSCs and CRISPR-Cas9 mediated UBE3A KO hESCs, we uncovered a novel role of UBE3A in suppressing neuronal hyperexcitability via ubiquitin-mediated degradation of BK channels."
    explanation: Supports relevance for human-cell-model mechanisms linking UBE3A loss to neuronal hyperexcitability.
- accession: geo:GSE146640
  title: Differences in transcription in Angelman syndrome and control person iPSC-derived neurons
  description: >-
    Human iPSC-neuron transcriptome dataset comparing Angelman syndrome and
    control lines to characterize disease-associated transcriptional changes.
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  data_type: BULK_RNA_SEQ
  sample_count: 6
  conditions:
  - Angelman syndrome iPSC-derived neurons
  - control iPSC-derived neurons
  evidence:
  - reference: GEO:GSE146640
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "So we wanted to study differences in the transcriptome in neurons differentiated from iPSCs that were derived from patients with Angleman syndrome and normal controls."
    explanation: Supports direct disease-vs-control transcriptomic comparison in human neuron-like cells.
- accession: geo:GSE160747
  title: Establishing a molecular phenotype for Angelman Syndrome stem cell-derived neurons
  description: >-
    Human stem-cell neuron RNA-seq dataset spanning isogenic control versus
    Angelman syndrome neuronal models and antisense-oligonucleotide intervention
    conditions relevant to UBE3A reinstatement biology.
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  data_type: BULK_RNA_SEQ
  sample_count: 36
  conditions:
  - isogenic control and Angelman syndrome pluripotent stem cell-derived neurons
  - UBE3A ASO-treated H9 hESC-derived neurons
  - scramble ASO-treated H9 hESC-derived neurons
  evidence:
  - reference: GEO:GSE160747
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: "mRNAseq on (1) isogenic control and Angelman Syndrome pluripotent stem cell-derived neurons or (2) antisense oligonucleotide-treated H9 hESC-derived neurons"
    explanation: Supports mechanistically relevant transcriptomic profiling in human AS neuronal models and ASO-treated conditions.
- accession: geo:GSE284678
  title: UBE3A reinstatement restores behavior and proteome in an Angelman syndrome mouse model of imprinting defects
  description: >-
    Mouse RNA-seq resource from an imprinting-center Angelman model (mICD/UPD
    relevant) with UBE3A reinstatement interventions to evaluate rescue of
    molecular and behavioral phenotypes.
  organism:
    preferred_term: house mouse
    term:
      id: NCBITaxon:10090
      label: Mus musculus
  data_type: BULK_RNA_SEQ
  sample_count: 14
  conditions:
  - mICD Angelman model mice
  - UBE3A reinstatement conditions
  - control mice
  publication: PMID:40877933
  evidence:
  - reference: GEO:GSE284678
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "mICD mice showed significant reduction in UBE3A protein, bi-allelic expression of Ube3a-ATS and Mkrn3-Snord115 gene cluster, leading to robust AS behavioral deficits and proteome alterations similar to Ube3aKO mice."
    explanation: Supports utility of this model for transcriptomic interrogation of imprinting-related Angelman pathophysiology.
  - reference: GEO:GSE284678
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Genetic UBE3A overexpression in mICD mice, mimicking therapeutic strategies that effectively activate the biallelic silenced Ube3a gene, resulted in a complete rescue of all behavioral and proteome alterations."
    explanation: Adds mechanistic rescue context relevant to disease-modifying therapy modeling.
- accession: geo:GSE32563
  title: Differential Gene Expression in Angelman syndrome deletion vs. int dup(15) Human Lymphocytes
  description: >-
    Human peripheral-blood microarray dataset comparing Angelman deletion cases
    and reciprocal 15q duplication cases to identify shared and divergent
    transcriptional signatures.
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  data_type: MICROARRAY
  sample_count: 6
  conditions:
  - Angelman syndrome deletion
  - interstitial duplication 15q autism
  evidence:
  - reference: GEO:GSE32563
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Microarray analysis revealed 1225 genes that were elevated in AS deletion vs int dup(15) and 976 genes that were elevated in int dup(15) vs AS deletion PBMC (pvalue<0.05)."
    explanation: Supports this dataset as a human comparative transcriptomic resource connected to UBE3A-region disorders.
clinical_trials:
- name: NCT04428281
  phase: PHASE_I
  status: COMPLETED
  description: >-
    Open-label intrathecal antisense-oligonucleotide trial evaluating
    RO7248824 safety, tolerability, PK, and PD in participants with Angelman
    syndrome.
  evidence:
  - reference: clinicaltrials:NCT04428281
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "This is a phase I, multicenter, non-randomized, adaptive, open-label, multiple ascending, intra-participant, dose-escalation study with a long-term extension (LTE) part and an optional open-label extension (OOE) part."
    explanation: Supports active clinical development of UBE3A-unsilencing therapy.
- name: NCT04259281
  phase: PHASE_I
  status: COMPLETED
  description: >-
    Early-phase intrathecal GTX-102 antisense-oligonucleotide study (Phase 1/2)
    in pediatric Angelman syndrome.
  evidence:
  - reference: clinicaltrials:NCT04259281
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The primary objective of the study is to evaluate the safety and tolerability of multiple-ascending doses of GTX-102 administered by intrathecal (IT) injection to participants with Angelman Syndrome (AS)."
    explanation: Supports clinical translation of UBE3A-restoration strategies.
  notes: Trial title indicates Phase 1/2 design; mapped to PHASE_I given schema granularity (no combined Phase 1/2 enum value).
- name: NCT04106557
  phase: PHASE_III
  status: COMPLETED
  description: >-
    Randomized placebo-controlled phase III study of oral OV101 (gaboxadol) in
    pediatric Angelman syndrome.
  target_phenotypes:
  - preferred_term: Sleep disturbance
    term:
      id: HP:0002360
      label: Sleep disturbance
  evidence:
  - reference: clinicaltrials:NCT04106557
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The purpose of this study is to assess the efficacy and safety of oral OV101 (gaboxadol) in pediatric subjects with Angelman syndrome."
    explanation: Supports late-stage therapeutic evaluation in AS.
- name: NCT05127226
  phase: PHASE_I
  status: RECRUITING
  description: >-
    HALOS - intrathecal antisense oligonucleotide ION582 (Ionis) safety,
    tolerability, pharmacokinetics, and pharmacodynamics study in participants
    with Angelman syndrome.
  evidence:
  - reference: clinicaltrials:NCT05127226
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The purpose of this study is to evaluate the safety and tolerability of ascending doses of ION582 administered intrathecally in participants with Angelman syndrome."
    explanation: Supports active clinical evaluation of an alternative ASO program (ION582) for paternal UBE3A reactivation.
- name: NCT06617429
  phase: PHASE_III
  status: ACTIVE_NOT_RECRUITING
  description: >-
    Phase 3, randomized, double-blind, sham-controlled study evaluating
    intrathecal GTX-102 (apazunersen) for cognitive function in pediatric
    deletion-type Angelman syndrome.
  target_phenotypes:
  - preferred_term: Severe intellectual disability
    term:
      id: HP:0010864
      label: Severe intellectual disability
  evidence:
  - reference: clinicaltrials:NCT06617429
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The primary objective of this study is to evaluate the effect of GTX-102 in cognitive function in participants with deletion-type Angelman Syndrome (AS)."
    explanation: Supports pivotal Phase 3 evaluation of UBE3A-restoring ASO therapy in deletion-type AS.
- name: NCT07157254
  phase: PHASE_II
  status: RECRUITING
  description: >-
    Phase 2 open-label basket study of GTX-102 in adult and pediatric subjects
    with deletion- or non-deletion-type Angelman syndrome to evaluate safety
    and efficacy across genotypes.
  evidence:
  - reference: clinicaltrials:NCT07157254
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The main goal of the study is to evaluate the safety and efficacy of GTX-102 in participants with Angelman syndrome."
    explanation: Supports basket evaluation of GTX-102 across all major AS molecular subtypes.
- name: NCT06415344
  phase: PHASE_III
  status: ENROLLING_BY_INVITATION
  description: >-
    Long-term extension trial of intrathecal GTX-102 (apazunersen) evaluating
    long-term safety and efficacy in participants with Angelman syndrome who
    completed prior GTX-102 studies.
  evidence:
  - reference: clinicaltrials:NCT06415344
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The primary objective of the study is to evaluate the long-term safety profile of GTX-102 in participants with Angelman Syndrome (AS)"
    explanation: Supports long-term safety follow-up for the GTX-102 ASO program.
notes: >-
  Contemporary consensus guidance emphasizes standardized multidisciplinary care
  as a prerequisite for evaluating emerging disease-modifying therapies in
  Angelman syndrome. Disease-modifying programs in active clinical development
  include intrathecal antisense oligonucleotides targeting UBE3A-ATS (ION582,
  GTX-102/apazunersen, rugonersen), AAV gene replacement (MVX-220), CRISPR/Cas13
  unsilencing, and small-molecule paternal-allele unsilencers; quantitative EEG
  delta power is the most translatable biomarker for these trials. Genotype
  stratification is increasingly recognized as essential, with deletion-type
  AS showing more severe and earlier-onset epilepsy attributable to GABRB3-
  GABRA5-GABRG3 hemizygosity and a distinct OCA2-mediated oculoalbinism
  phenotype.
references:
- reference: PMID:20301323
  title: "Angelman Syndrome."
  tags:
  - GeneReviews
  findings: []
- reference: DOI:10.1016/j.ymthe.2022.05.014
  title: Gene-based therapeutics for rare genetic neurodevelopmental psychiatric disorders
  found_in:
  - Angelman_Syndrome-deep-research-falcon.md
  findings:
  - statement: Gene-based therapeutics for rare genetic neurodevelopmental psychiatric disorders
    supporting_text: Gene-based therapeutics for rare genetic neurodevelopmental psychiatric disorders
- reference: DOI:10.1016/j.ymthe.2023.02.015
  title: A high-fidelity RNA-targeting Cas13 restores paternal Ube3a expression and improves motor functions in Angelman syndrome mice
  found_in:
  - Angelman_Syndrome-deep-research-falcon.md
  findings:
  - statement: A high-fidelity RNA-targeting Cas13 restores paternal Ube3a expression and improves motor functions in Angelman syndrome mice
    supporting_text: A high-fidelity RNA-targeting Cas13 restores paternal Ube3a expression and improves motor functions in Angelman syndrome mice
- reference: DOI:10.1038/s41467-024-49788-8
  title: Ube3a unsilencer for the potential treatment of Angelman syndrome
  found_in:
  - Angelman_Syndrome-deep-research-falcon.md
  findings:
  - statement: Deletion of the maternal UBE3A allele causes Angelman syndrome (AS); because paternal UBE3A is epigenetically silenced by a long non-coding antisense (UBE3A-ATS) in neurons, this nearly eliminates UBE3A protein in the brain.
    supporting_text: Deletion of the maternal UBE3A allele causes Angelman syndrome (AS); because paternal UBE3A is epigenetically silenced by a long non-coding antisense (UBE3A-ATS) in neurons, this nearly eliminates UBE3A protein in the brain.
- reference: DOI:10.1080/13543784.2021.1939674
  title: Therapies in preclinical and clinical development for Angelman syndrome
  found_in:
  - Angelman_Syndrome-deep-research-falcon.md
  findings:
  - statement: Therapies in preclinical and clinical development for Angelman syndrome
    supporting_text: Therapies in preclinical and clinical development for Angelman syndrome
- reference: DOI:10.1101/2022.06.18.496687
  title: Antisense oligonucleotide therapy rescues disturbed brain rhythms and sleep in juvenile and adult mouse models of Angelman syndrome
  found_in:
  - Angelman_Syndrome-deep-research-falcon.md
  findings:
  - statement: UBE3A encodes ubiquitin protein ligase E3A, and in neurons its expression from the paternal allele is repressed by the UBE3A antisense transcript ( UBE3A-ATS ).
    supporting_text: UBE3A encodes ubiquitin protein ligase E3A, and in neurons its expression from the paternal allele is repressed by the UBE3A antisense transcript ( UBE3A-ATS ).
- reference: DOI:10.1523/eneuro.0345-20.2020
  title: Early Developmental EEG and Seizure Phenotypes in a Full Gene Deletion of Ubiquitin Protein Ligase E3A Rat Model of Angelman Syndrome
  found_in:
  - Angelman_Syndrome-deep-research-falcon.md
  findings:
  - statement: Angelman syndrome (AS) is a neurodevelopmental disorder with unique behavioral phenotypes, seizures, and distinctive electroencephalographic (EEG) patterns.
    supporting_text: Angelman syndrome (AS) is a neurodevelopmental disorder with unique behavioral phenotypes, seizures, and distinctive electroencephalographic (EEG) patterns.
- reference: DOI:10.3389/fcell.2023.1274040
  title: Stem cell models of Angelman syndrome
  found_in:
  - Angelman_Syndrome-deep-research-falcon.md
  findings:
  - statement: Angelman syndrome (AS) is an imprinted neurodevelopmental disorder that lacks a cure, characterized by developmental delay, intellectual impairment, seizures, ataxia, and paroxysmal laughter.
    supporting_text: Angelman syndrome (AS) is an imprinted neurodevelopmental disorder that lacks a cure, characterized by developmental delay, intellectual impairment, seizures, ataxia, and paroxysmal laughter.
- reference: DOI:10.3389/fcell.2024.1413248
  title: Epigenetics in rare neurological diseases
  found_in:
  - Angelman_Syndrome-deep-research-falcon.md
  findings:
  - statement: Rare neurological diseases include a vast group of heterogenous syndromes with primary impairment(s) in the peripheral and/or central nervous systems.
    supporting_text: Rare neurological diseases include a vast group of heterogenous syndromes with primary impairment(s) in the peripheral and/or central nervous systems.
- reference: DOI:10.3389/fnana.2024.1410791
  title: Regional and cellular organization of the autism-associated protein UBE3A/E6AP and its antisense transcript in the brain of the developing rhesus monkey
  found_in:
  - Angelman_Syndrome-deep-research-falcon.md
  findings:
  - statement: Angelman syndrome (AS) is a neurogenetic disorder caused by mutations or deletions in the maternally-inherited UBE3A allele, leading to a loss of UBE3A protein expression in neurons.
    supporting_text: Angelman syndrome (AS) is a neurogenetic disorder caused by mutations or deletions in the maternally-inherited UBE3A allele, leading to a loss of UBE3A protein expression in neurons.
- reference: DOI:10.3390/genes12070987
  title: Genotype–Phenotype Correlations in Angelman Syndrome
  found_in:
  - Angelman_Syndrome-deep-research-falcon.md
  findings:
  - statement: 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.
    supporting_text: 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.
- reference: PMID:10684875
  title: Reciprocal inhibitory connections regulate the spatiotemporal properties of intrathalamic oscillations.
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2000 Mar 1;20(5):1735-45. doi: 10.1523/JNEUROSCI.20-05-01735.2000.'
    supporting_text: '2000 Mar 1;20(5):1735-45. doi: 10.1523/JNEUROSCI.20-05-01735.2000.'
- reference: PMID:11748306
  title: Distinct phenotypes distinguish the molecular classes of Angelman syndrome.
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: Angelman syndrome (AS) is a severe neurobehavioural disorder caused by defects in the maternally derived imprinted domain located on 15q11-q13.
    supporting_text: Angelman syndrome (AS) is a severe neurobehavioural disorder caused by defects in the maternally derived imprinted domain located on 15q11-q13.
- reference: PMID:20459762
  title: Practice guidelines for the molecular analysis of Prader-Willi and Angelman syndromes.
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: Prader-Willi syndrome (PWS) and Angelman syndrome (AS) are clinically distinct neurodevelopmental genetic disorders that map to 15q11-q13.
    supporting_text: Prader-Willi syndrome (PWS) and Angelman syndrome (AS) are clinically distinct neurodevelopmental genetic disorders that map to 15q11-q13.
- reference: PMID:20808828
  title: Altered ultrasonic vocalization and impaired learning and memory in Angelman syndrome mouse model with a large maternal deletion from Ube3a to Gabrb3.
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2010 Aug 20;5(8):e12278. doi: 10.1371/journal.pone.0012278.'
    supporting_text: '2010 Aug 20;5(8):e12278. doi: 10.1371/journal.pone.0012278.'
- reference: PMID:22190039
  title: Topoisomerase inhibitors unsilence the dormant allele of Ube3a in neurons.
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2011 Dec 21;481(7380):185-9. doi: 10.1038/nature10726.'
    supporting_text: '2011 Dec 21;481(7380):185-9. doi: 10.1038/nature10726.'
- reference: PMID:23918391
  title: R-loop formation at Snord116 mediates topotecan inhibition of Ube3a-antisense and allele-specific chromatin decondensation.
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2013 Aug 20;110(34):13938-43. doi: 10.1073/pnas.1305426110.'
    supporting_text: '2013 Aug 20;110(34):13938-43. doi: 10.1073/pnas.1305426110.'
- reference: PMID:25470045
  title: Towards a therapy for Angelman syndrome by targeting a long non-coding RNA.
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2015 Feb 19;518(7539):409-12. doi: 10.1038/nature13975.'
    supporting_text: '2015 Feb 19;518(7539):409-12. doi: 10.1038/nature13975.'
- reference: PMID:25684537
  title: Administration of CoQ10 analogue ameliorates dysfunction of the mitochondrial respiratory chain in a mouse model of Angelman syndrome.
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2015 Apr;76:77-86. doi: 10.1016/j.nbd.2015.01.005.'
    supporting_text: '2015 Apr;76:77-86. doi: 10.1016/j.nbd.2015.01.005.'
- reference: PMID:26658871
  title: Mitochondrial Superoxide Contributes to Hippocampal Synaptic Dysfunction and Memory Deficits in Angelman Syndrome Model Mice.
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2015 Dec 9;35(49):16213-20. doi: 10.1523/JNEUROSCI.2246-15.2015.'
    supporting_text: '2015 Dec 9;35(49):16213-20. doi: 10.1523/JNEUROSCI.2246-15.2015.'
- reference: PMID:27986596
  title: Effects of the synthetic neurosteroid ganaxolone on seizure activity and behavioral deficits in an Angelman syndrome mouse model.
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2017 Apr;116:142-150. doi: 10.1016/j.neuropharm.2016.12.009.'
    supporting_text: '2017 Apr;116:142-150. doi: 10.1016/j.neuropharm.2016.12.009.'
- reference: PMID:28814801
  title: Strain-dependence of the Angelman Syndrome phenotypes in Ube3a maternal deficiency mice.
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2017 Aug 16;7(1):8451. doi: 10.1038/s41598-017-08825-x.'
    supporting_text: '2017 Aug 16;7(1):8451. doi: 10.1038/s41598-017-08825-x.'
- reference: PMID:28890050
  title: Modulation of hippocampal synapse maturation by activity-regulated E3 ligase via non-canonical pathway.
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2017 Nov 19;364:226-241. doi: 10.1016/j.neuroscience.2017.08.057.'
    supporting_text: '2017 Nov 19;364:226-241. doi: 10.1016/j.neuroscience.2017.08.057.'
- reference: PMID:28931574
  title: Enhanced Nociception in Angelman Syndrome Model Mice.
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2017 Oct 18;37(42):10230-10239. doi: 10.1523/JNEUROSCI.1018-17.2017.'
    supporting_text: '2017 Oct 18;37(42):10230-10239. doi: 10.1523/JNEUROSCI.1018-17.2017.'
- reference: PMID:30082419
  title: Adult Ube3a Gene Reinstatement Restores the Electrophysiological Deficits of Prefrontal Cortex Layer 5 Neurons in a Mouse Model of Angelman Syndrome.
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2018 Sep 12;38(37):8011-8030. doi: 10.1523/JNEUROSCI.0083-18.2018.'
    supporting_text: '2018 Sep 12;38(37):8011-8030. doi: 10.1523/JNEUROSCI.0083-18.2018.'
- reference: PMID:30548424
  title: Identification of a de novo splicing variant in the Coffin-Siris gene, SMARCE1, in a patient with Angelman-like syndrome.
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: Patients affected by Angelman syndrome (AS) present severe intellectual disability, lack of speech, ataxia, seizures, abnormal electroencephalography (EEG), and a characteristic behavioral phenotype.
    supporting_text: Patients affected by Angelman syndrome (AS) present severe intellectual disability, lack of speech, ataxia, seizures, abnormal electroencephalography (EEG), and a characteristic behavioral phenotype.
- reference: PMID:30680721
  title: Gene mutations in paediatric epilepsies cause NMDA-pathy, and phasic and tonic GABA-pathy.
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2019 Aug;61(8):891-898. doi: 10.1111/dmcn.14152.'
    supporting_text: '2019 Aug;61(8):891-898. doi: 10.1111/dmcn.14152.'
- reference: PMID:32088294
  title: 'Angelman Syndrome: From Mouse Models to Therapy.'
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2020 Oct 1;445:172-189. doi: 10.1016/j.neuroscience.2020.02.017.'
    supporting_text: '2020 Oct 1;445:172-189. doi: 10.1016/j.neuroscience.2020.02.017.'
- reference: PMID:32269945
  title: 'Clinical characteristics and epilepsy in genomic imprinting disorders: Angelman syndrome and Prader-Willi syndrome.'
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2019 Oct 31;32(2):137-144. doi: 10.4103/tcmj.tcmj_103_19. eCollection 2020 Apr-Jun.'
    supporting_text: '2019 Oct 31;32(2):137-144. doi: 10.4103/tcmj.tcmj_103_19. eCollection 2020 Apr-Jun.'
- reference: PMID:32532103
  title: Bioinformatics Analyses of the Transcriptome Reveal Ube3a-Dependent Effects on Mitochondrial-Related Pathways.
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2020 Jun 10;21(11):4156. doi: 10.3390/ijms21114156.'
    supporting_text: '2020 Jun 10;21(11):4156. doi: 10.3390/ijms21114156.'
- reference: PMID:32713229
  title: Iron Deficiency and Its Role in Sleep Disruption in Patients With Angelman Syndrome.
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: About two-thirds of Angelman syndrome patients experience sleep difficulties, which are likely multifactorial.
    supporting_text: About two-thirds of Angelman syndrome patients experience sleep difficulties, which are likely multifactorial.
- reference: PMID:32792659
  title: Angelman syndrome genotypes manifest varying degrees of clinical severity and developmental impairment.
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2021 Jul;26(7):3625-3633. doi: 10.1038/s41380-020-0858-6.'
    supporting_text: '2021 Jul;26(7):3625-3633. doi: 10.1038/s41380-020-0858-6.'
- reference: PMID:32817301
  title: Evaluation of a TrkB agonist on spatial and motor learning in the Ube3a mouse model of Angelman syndrome.
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2020 Aug 17;27(9):346-354. doi: 10.1101/lm.051201.119.'
    supporting_text: '2020 Aug 17;27(9):346-354. doi: 10.1101/lm.051201.119.'
- reference: PMID:32893075
  title: 'Epilepsy in Angelman syndrome: A scoping review.'
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2021 Jan;43(1):32-44. doi: 10.1016/j.braindev.2020.08.014.'
    supporting_text: '2021 Jan;43(1):32-44. doi: 10.1016/j.braindev.2020.08.014.'
- reference: PMID:32976638
  title: 'Angelman syndrome and melatonin: What can they teach us about sleep regulation.'
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2020 Nov;69(4):e12697. doi: 10.1111/jpi.12697.'
    supporting_text: '2020 Nov;69(4):e12697. doi: 10.1111/jpi.12697.'
- reference: PMID:33370574
  title: 'Patient-derived iPSC modeling of rare neurodevelopmental disorders: Molecular pathophysiology and prospective therapies.'
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2021 Feb;121:201-219. doi: 10.1016/j.neubiorev.2020.12.025.'
    supporting_text: '2021 Feb;121:201-219. doi: 10.1016/j.neubiorev.2020.12.025.'
- reference: PMID:33549123
  title: Abnormal electrophysiological phenotypes and sleep deficits in a mouse model of Angelman Syndrome.
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: Angelman Syndrome (AS) is a rare genetic disorder characterized by impaired communication, motor and balance deficits, intellectual disabilities, recurring seizures and abnormal sleep patterns.
    supporting_text: Angelman Syndrome (AS) is a rare genetic disorder characterized by impaired communication, motor and balance deficits, intellectual disabilities, recurring seizures and abnormal sleep patterns.
- reference: PMID:34653234
  title: 'New genes involved in Angelman syndrome-like: Expanding the genetic spectrum.'
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2021 Oct 15;16(10):e0258766. doi: 10.1371/journal.pone.0258766. eCollection 2021.'
    supporting_text: '2021 Oct 15;16(10):e0258766. doi: 10.1371/journal.pone.0258766. eCollection 2021.'
- reference: PMID:35904299
  title: '[Epilepsy in Angelman syndrome].'
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2022;122(7):100-105. doi: 10.17116/jnevro2022122071100. [Epilepsy in Angelman syndrome]. [Article in Russian; Abstract available in Russian from the publisher] Bobylova MY(1), Mukhin KY(1), Kuzmich GV(1), Glukhova LY(1), Pylayeva OA(1).'
    supporting_text: '2022;122(7):100-105. doi: 10.17116/jnevro2022122071100. [Epilepsy in Angelman syndrome]. [Article in Russian; Abstract available in Russian from the publisher] Bobylova MY(1), Mukhin KY(1), Kuzmich GV(1), Glukhova LY(1), Pylayeva OA(1).'
- reference: PMID:35917229
  title: Therapeutic approach to neurological manifestations of Angelman syndrome.
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2022 Jul;15(7):843-850. doi: 10.1080/17512433.2022.2109463.'
    supporting_text: '2022 Jul;15(7):843-850. doi: 10.1080/17512433.2022.2109463.'
- reference: PMID:38327047
  title: Prenatal delivery of a therapeutic antisense oligonucleotide achieves broad biodistribution in the brain and ameliorates Angelman syndrome phenotype in mice.
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2024 Apr 3;32(4):935-951. doi: 10.1016/j.ymthe.2024.02.004.'
    supporting_text: '2024 Apr 3;32(4):935-951. doi: 10.1016/j.ymthe.2024.02.004.'
- reference: PMID:39045627
  title: Integration of CTCF loops, methylome, and transcriptome in differentiating LUHMES as a model for imprinting dynamics of the 15q11-q13 locus in human neurons.
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2024 Sep 19;33(19):1711-1725. doi: 10.1093/hmg/ddae111.'
    supporting_text: '2024 Sep 19;33(19):1711-1725. doi: 10.1093/hmg/ddae111.'
- reference: PMID:39293689
  title: Multiscale spatio-temporal dynamics of UBE3A gene in brain physiology and neurodevelopmental disorders.
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2024 Oct 15;201:106669. doi: 10.1016/j.nbd.2024.106669.'
    supporting_text: '2024 Oct 15;201:106669. doi: 10.1016/j.nbd.2024.106669.'
- reference: PMID:39404036
  title: '[Epilepsy in Angelman syndrome and the most common electroencephalographic findings].'
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '[Epilepsy in Angelman syndrome and the most common electroencephalographic findings]'
    supporting_text: '2024 Oct 16;79(8):223-228. doi: 10.33588/rn.7908.2024233. [Epilepsy in Angelman syndrome and the most common electroencephalographic findings]. [Article in Spanish; Abstract available in Spanish from the publisher] Ebrat-Mancilla E(1), Sánchez-Aparicio A(1), Pérez de Vargas-Martínez A(1), Marín-Serrano ME(1), Vaquero-Martínez M(1), Iglesias-Escalera G(1), Cazorla MR(1), López-Pájaro LF(1).'
- reference: PMID:39726042
  title: Comparative profiling of white matter development in the human and mouse brain reveals volumetric deficits and delayed myelination in Angelman syndrome.
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: Angelman syndrome (AS), a severe neurodevelopmental disorder resulting from the loss of the maternal UBE3A gene, is marked by changes in the brain's white matter (WM).
    supporting_text: Angelman syndrome (AS), a severe neurodevelopmental disorder resulting from the loss of the maternal UBE3A gene, is marked by changes in the brain's white matter (WM).
- reference: PMID:40116126
  title: Age-Related Trajectories of Autistic Traits in Children With Angelman Syndrome.
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2025 Apr;18(4):870-880. doi: 10.1002/aur.70017.'
    supporting_text: '2025 Apr;18(4):870-880. doi: 10.1002/aur.70017.'
- reference: PMID:40200228
  title: Lower respiratory rate during sleep in children with angelman syndrome compared to age-matched controls.
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: Angelman syndrome (AS) is a rare genetic neurodevelopmental disorder caused by the absence of a functional UBE3A gene, leading to developmental, behavioral, and medical challenges.
    supporting_text: Angelman syndrome (AS) is a rare genetic neurodevelopmental disorder caused by the absence of a functional UBE3A gene, leading to developmental, behavioral, and medical challenges.
- reference: PMID:40484454
  title: 'Health outcomes of children with Prader-Willi or Angelman syndromes: a European population-based multicentre study.'
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2025 Oct 17;110(11):899-904. doi: 10.1136/archdischild-2025-328786.'
    supporting_text: '2025 Oct 17;110(11):899-904. doi: 10.1136/archdischild-2025-328786.'
- reference: PMID:40801290
  title: High-throughput assessment of FMR1 and SNRPN methylation-based newborn screening using IsoPure and QIAcube HT systems.
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2025 Sep;17(13):851-863. doi: 10.1080/17501911.2025.2544530.'
    supporting_text: '2025 Sep;17(13):851-863. doi: 10.1080/17501911.2025.2544530.'
- reference: PMID:40852931
  title: 'Assessment of Dysphagia in Chinese Cohort of Angelman Syndrome: An Observational Study.'
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2025 Aug;31(8):e70587. doi: 10.1111/cns.70587.'
    supporting_text: '2025 Aug;31(8):e70587. doi: 10.1111/cns.70587.'
- reference: PMID:41153459
  title: 'Imprinting Disorders and Epigenetic Alterations in Children Conceived by Assisted Reproductive Technologies: Mechanisms, Clinical Outcomes, and Prenatal Diagnosis.'
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2025 Oct 21;16(10):1242. doi: 10.3390/genes16101242.'
    supporting_text: '2025 Oct 21;16(10):1242. doi: 10.3390/genes16101242.'
- reference: PMID:41525882
  title: 'The Italian Angelman Syndrome Registry (IReAS): a tool for standardized data collection and genotype-phenotype analysis.'
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: Angelman syndrome (AS) is a rare and heterogeneous genetic disorder characterized by intellectual and psychomotor delay, speech deficits, seizures and behavioural issues.
    supporting_text: Angelman syndrome (AS) is a rare and heterogeneous genetic disorder characterized by intellectual and psychomotor delay, speech deficits, seizures and behavioural issues.
- reference: PMID:41630268
  title: 'Adjunctive cannabidiol in intractable pediatric epilepsy: A retrospective study on tolerability, efficacy, and safety across genetic and nongenetic etiologies.'
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings:
  - statement: '2026 Jan 30;105(5):e47425. doi: 10.1097/MD.0000000000047425.'
    supporting_text: '2026 Jan 30;105(5):e47425. doi: 10.1097/MD.0000000000047425.'
- reference: PMID:37051256
  title: 'Prader-Willi and Angelman Syndromes: Mechanisms and Management.'
  found_in:
  - Angelman_Syndrome-deep-research-falcon.md
  findings:
  - statement: '2023 Apr 6;16:41-52. doi: 10.2147/TACG.S372708. eCollection 2023.'
    supporting_text: '2023 Apr 6;16:41-52. doi: 10.2147/TACG.S372708. eCollection 2023.'
- reference: DOI:10.1016/j.biopsych.2019.01.008
  title: Electrophysiological Phenotype in Angelman Syndrome Differs Between Genotypes
  found_in:
  - Angelman_Syndrome-deep-research-falcon.md
  findings: []
- reference: DOI:10.1016/j.pediatrneurol.2021.08.007
  title: Clinical Characterization of Epilepsy in Children With Angelman Syndrome
  found_in:
  - Angelman_Syndrome-deep-research-falcon.md
  findings: []
- reference: DOI:10.1093/braincomms/fcac106
  title: Longitudinal EEG model detects antisense oligonucleotide treatment effect and increased UBE3A in Angelman syndrome
  found_in:
  - Angelman_Syndrome-deep-research-falcon.md
  findings: []
- reference: DOI:10.1177/1550059420973095
  title: 'Quantitative EEG Analysis in Angelman Syndrome: Candidate Method for Assessing Therapeutics'
  found_in:
  - Angelman_Syndrome-deep-research-falcon.md
  findings: []
- reference: DOI:10.1186/s13229-018-0214-8
  title: 'Abnormal coherence and sleep composition in children with Angelman syndrome: a retrospective EEG study'
  found_in:
  - Angelman_Syndrome-deep-research-falcon.md
  findings: []
- reference: PMID:35862628
  title: Pharmacotherapeutic management of seizures in patients with Angleman Syndrome.
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings: []
- reference: PMID:40776598
  title: Outcomes After Tonsillectomy in Children With Angelman Syndrome.
  found_in:
  - Angelman_Syndrome-deep-research-openscientist.md
  findings: []

📚

References & Deep Research

References

PMID:20301323

Angelman Syndrome.

No top-level findings curated for this source.

DOI:10.1016/j.ymthe.2022.05.014

Gene-based therapeutics for rare genetic neurodevelopmental psychiatric disorders

1 finding

Gene-based therapeutics for rare genetic neurodevelopmental psychiatric disorders

"Gene-based therapeutics for rare genetic neurodevelopmental psychiatric disorders"

DOI:10.1016/j.ymthe.2023.02.015

A high-fidelity RNA-targeting Cas13 restores paternal Ube3a expression and improves motor functions in Angelman syndrome mice

1 finding

A high-fidelity RNA-targeting Cas13 restores paternal Ube3a expression and improves motor functions in Angelman syndrome mice

"A high-fidelity RNA-targeting Cas13 restores paternal Ube3a expression and improves motor functions in Angelman syndrome mice"

DOI:10.1038/s41467-024-49788-8

Ube3a unsilencer for the potential treatment of Angelman syndrome

1 finding

Deletion of the maternal UBE3A allele causes Angelman syndrome (AS); because paternal UBE3A is epigenetically silenced by a long non-coding antisense (UBE3A-ATS) in neurons, this nearly eliminates UBE3A protein in the brain.

"Deletion of the maternal UBE3A allele causes Angelman syndrome (AS); because paternal UBE3A is epigenetically silenced by a long non-coding antisense (UBE3A-ATS) in neurons, this nearly eliminates UBE3A protein in the brain."

DOI:10.1080/13543784.2021.1939674

Therapies in preclinical and clinical development for Angelman syndrome

1 finding

Therapies in preclinical and clinical development for Angelman syndrome

"Therapies in preclinical and clinical development for Angelman syndrome"

DOI:10.1101/2022.06.18.496687

Antisense oligonucleotide therapy rescues disturbed brain rhythms and sleep in juvenile and adult mouse models of Angelman syndrome

1 finding

UBE3A encodes ubiquitin protein ligase E3A, and in neurons its expression from the paternal allele is repressed by the UBE3A antisense transcript ( UBE3A-ATS ).

"UBE3A encodes ubiquitin protein ligase E3A, and in neurons its expression from the paternal allele is repressed by the UBE3A antisense transcript ( UBE3A-ATS )."

DOI:10.1523/eneuro.0345-20.2020

Early Developmental EEG and Seizure Phenotypes in a Full Gene Deletion of Ubiquitin Protein Ligase E3A Rat Model of Angelman Syndrome

1 finding

Angelman syndrome (AS) is a neurodevelopmental disorder with unique behavioral phenotypes, seizures, and distinctive electroencephalographic (EEG) patterns.

"Angelman syndrome (AS) is a neurodevelopmental disorder with unique behavioral phenotypes, seizures, and distinctive electroencephalographic (EEG) patterns."

DOI:10.3389/fcell.2023.1274040

Stem cell models of Angelman syndrome

1 finding

Angelman syndrome (AS) is an imprinted neurodevelopmental disorder that lacks a cure, characterized by developmental delay, intellectual impairment, seizures, ataxia, and paroxysmal laughter.

"Angelman syndrome (AS) is an imprinted neurodevelopmental disorder that lacks a cure, characterized by developmental delay, intellectual impairment, seizures, ataxia, and paroxysmal laughter."

DOI:10.3389/fcell.2024.1413248

Epigenetics in rare neurological diseases

1 finding

Rare neurological diseases include a vast group of heterogenous syndromes with primary impairment(s) in the peripheral and/or central nervous systems.

"Rare neurological diseases include a vast group of heterogenous syndromes with primary impairment(s) in the peripheral and/or central nervous systems."

DOI:10.3389/fnana.2024.1410791

Regional and cellular organization of the autism-associated protein UBE3A/E6AP and its antisense transcript in the brain of the developing rhesus monkey

1 finding

Angelman syndrome (AS) is a neurogenetic disorder caused by mutations or deletions in the maternally-inherited UBE3A allele, leading to a loss of UBE3A protein expression in neurons.

"Angelman syndrome (AS) is a neurogenetic disorder caused by mutations or deletions in the maternally-inherited UBE3A allele, leading to a loss of UBE3A protein expression in neurons."

DOI:10.3390/genes12070987

Genotype–Phenotype Correlations in Angelman Syndrome

1 finding

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.

"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."

PMID:10684875

Reciprocal inhibitory connections regulate the spatiotemporal properties of intrathalamic oscillations.

1 finding

2000 Mar 1;20(5):1735-45. doi: 10.1523/JNEUROSCI.20-05-01735.2000.

"2000 Mar 1;20(5):1735-45. doi: 10.1523/JNEUROSCI.20-05-01735.2000."

PMID:11748306

Distinct phenotypes distinguish the molecular classes of Angelman syndrome.

1 finding

Angelman syndrome (AS) is a severe neurobehavioural disorder caused by defects in the maternally derived imprinted domain located on 15q11-q13.

"Angelman syndrome (AS) is a severe neurobehavioural disorder caused by defects in the maternally derived imprinted domain located on 15q11-q13."

PMID:20459762

Practice guidelines for the molecular analysis of Prader-Willi and Angelman syndromes.

1 finding

Prader-Willi syndrome (PWS) and Angelman syndrome (AS) are clinically distinct neurodevelopmental genetic disorders that map to 15q11-q13.

"Prader-Willi syndrome (PWS) and Angelman syndrome (AS) are clinically distinct neurodevelopmental genetic disorders that map to 15q11-q13."

PMID:20808828

Altered ultrasonic vocalization and impaired learning and memory in Angelman syndrome mouse model with a large maternal deletion from Ube3a to Gabrb3.

1 finding

2010 Aug 20;5(8):e12278. doi: 10.1371/journal.pone.0012278.

"2010 Aug 20;5(8):e12278. doi: 10.1371/journal.pone.0012278."

PMID:22190039

Topoisomerase inhibitors unsilence the dormant allele of Ube3a in neurons.

1 finding

2011 Dec 21;481(7380):185-9. doi: 10.1038/nature10726.

"2011 Dec 21;481(7380):185-9. doi: 10.1038/nature10726."

PMID:23918391

R-loop formation at Snord116 mediates topotecan inhibition of Ube3a-antisense and allele-specific chromatin decondensation.

1 finding

2013 Aug 20;110(34):13938-43. doi: 10.1073/pnas.1305426110.

"2013 Aug 20;110(34):13938-43. doi: 10.1073/pnas.1305426110."

PMID:25470045

Towards a therapy for Angelman syndrome by targeting a long non-coding RNA.

1 finding

2015 Feb 19;518(7539):409-12. doi: 10.1038/nature13975.

"2015 Feb 19;518(7539):409-12. doi: 10.1038/nature13975."

PMID:25684537

Administration of CoQ10 analogue ameliorates dysfunction of the mitochondrial respiratory chain in a mouse model of Angelman syndrome.

1 finding

2015 Apr;76:77-86. doi: 10.1016/j.nbd.2015.01.005.

"2015 Apr;76:77-86. doi: 10.1016/j.nbd.2015.01.005."

PMID:26658871

Mitochondrial Superoxide Contributes to Hippocampal Synaptic Dysfunction and Memory Deficits in Angelman Syndrome Model Mice.

1 finding

2015 Dec 9;35(49):16213-20. doi: 10.1523/JNEUROSCI.2246-15.2015.

"2015 Dec 9;35(49):16213-20. doi: 10.1523/JNEUROSCI.2246-15.2015."

PMID:27986596

Effects of the synthetic neurosteroid ganaxolone on seizure activity and behavioral deficits in an Angelman syndrome mouse model.

1 finding

2017 Apr;116:142-150. doi: 10.1016/j.neuropharm.2016.12.009.

"2017 Apr;116:142-150. doi: 10.1016/j.neuropharm.2016.12.009."

PMID:28814801

Strain-dependence of the Angelman Syndrome phenotypes in Ube3a maternal deficiency mice.

1 finding

2017 Aug 16;7(1):8451. doi: 10.1038/s41598-017-08825-x.

"2017 Aug 16;7(1):8451. doi: 10.1038/s41598-017-08825-x."

PMID:28890050

Modulation of hippocampal synapse maturation by activity-regulated E3 ligase via non-canonical pathway.

1 finding

2017 Nov 19;364:226-241. doi: 10.1016/j.neuroscience.2017.08.057.

"2017 Nov 19;364:226-241. doi: 10.1016/j.neuroscience.2017.08.057."

PMID:28931574

Enhanced Nociception in Angelman Syndrome Model Mice.

1 finding

2017 Oct 18;37(42):10230-10239. doi: 10.1523/JNEUROSCI.1018-17.2017.

"2017 Oct 18;37(42):10230-10239. doi: 10.1523/JNEUROSCI.1018-17.2017."

PMID:30082419

Adult Ube3a Gene Reinstatement Restores the Electrophysiological Deficits of Prefrontal Cortex Layer 5 Neurons in a Mouse Model of Angelman Syndrome.

1 finding

2018 Sep 12;38(37):8011-8030. doi: 10.1523/JNEUROSCI.0083-18.2018.

"2018 Sep 12;38(37):8011-8030. doi: 10.1523/JNEUROSCI.0083-18.2018."

PMID:30548424

Identification of a de novo splicing variant in the Coffin-Siris gene, SMARCE1, in a patient with Angelman-like syndrome.

1 finding

Patients affected by Angelman syndrome (AS) present severe intellectual disability, lack of speech, ataxia, seizures, abnormal electroencephalography (EEG), and a characteristic behavioral phenotype.

"Patients affected by Angelman syndrome (AS) present severe intellectual disability, lack of speech, ataxia, seizures, abnormal electroencephalography (EEG), and a characteristic behavioral phenotype."

PMID:30680721

Gene mutations in paediatric epilepsies cause NMDA-pathy, and phasic and tonic GABA-pathy.

1 finding

2019 Aug;61(8):891-898. doi: 10.1111/dmcn.14152.

"2019 Aug;61(8):891-898. doi: 10.1111/dmcn.14152."

PMID:32088294

Angelman Syndrome: From Mouse Models to Therapy.

1 finding

2020 Oct 1;445:172-189. doi: 10.1016/j.neuroscience.2020.02.017.

"2020 Oct 1;445:172-189. doi: 10.1016/j.neuroscience.2020.02.017."

PMID:32269945

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

1 finding

2019 Oct 31;32(2):137-144. doi: 10.4103/tcmj.tcmj_103_19. eCollection 2020 Apr-Jun.

"2019 Oct 31;32(2):137-144. doi: 10.4103/tcmj.tcmj_103_19. eCollection 2020 Apr-Jun."

PMID:32532103

Bioinformatics Analyses of the Transcriptome Reveal Ube3a-Dependent Effects on Mitochondrial-Related Pathways.

1 finding

2020 Jun 10;21(11):4156. doi: 10.3390/ijms21114156.

"2020 Jun 10;21(11):4156. doi: 10.3390/ijms21114156."

PMID:32713229

Iron Deficiency and Its Role in Sleep Disruption in Patients With Angelman Syndrome.

1 finding

About two-thirds of Angelman syndrome patients experience sleep difficulties, which are likely multifactorial.

"About two-thirds of Angelman syndrome patients experience sleep difficulties, which are likely multifactorial."

PMID:32792659

Angelman syndrome genotypes manifest varying degrees of clinical severity and developmental impairment.

1 finding

2021 Jul;26(7):3625-3633. doi: 10.1038/s41380-020-0858-6.

"2021 Jul;26(7):3625-3633. doi: 10.1038/s41380-020-0858-6."

PMID:32817301

Evaluation of a TrkB agonist on spatial and motor learning in the Ube3a mouse model of Angelman syndrome.

1 finding

2020 Aug 17;27(9):346-354. doi: 10.1101/lm.051201.119.

"2020 Aug 17;27(9):346-354. doi: 10.1101/lm.051201.119."

PMID:32893075

Epilepsy in Angelman syndrome: A scoping review.

1 finding

2021 Jan;43(1):32-44. doi: 10.1016/j.braindev.2020.08.014.

"2021 Jan;43(1):32-44. doi: 10.1016/j.braindev.2020.08.014."

PMID:32976638

Angelman syndrome and melatonin: What can they teach us about sleep regulation.

1 finding

2020 Nov;69(4):e12697. doi: 10.1111/jpi.12697.

"2020 Nov;69(4):e12697. doi: 10.1111/jpi.12697."

PMID:33370574

Patient-derived iPSC modeling of rare neurodevelopmental disorders: Molecular pathophysiology and prospective therapies.

1 finding

2021 Feb;121:201-219. doi: 10.1016/j.neubiorev.2020.12.025.

"2021 Feb;121:201-219. doi: 10.1016/j.neubiorev.2020.12.025."

PMID:33549123

Abnormal electrophysiological phenotypes and sleep deficits in a mouse model of Angelman Syndrome.

1 finding

Angelman Syndrome (AS) is a rare genetic disorder characterized by impaired communication, motor and balance deficits, intellectual disabilities, recurring seizures and abnormal sleep patterns.

"Angelman Syndrome (AS) is a rare genetic disorder characterized by impaired communication, motor and balance deficits, intellectual disabilities, recurring seizures and abnormal sleep patterns."

PMID:34653234

New genes involved in Angelman syndrome-like: Expanding the genetic spectrum.

1 finding

2021 Oct 15;16(10):e0258766. doi: 10.1371/journal.pone.0258766. eCollection 2021.

"2021 Oct 15;16(10):e0258766. doi: 10.1371/journal.pone.0258766. eCollection 2021."

PMID:35904299

[Epilepsy in Angelman syndrome].

1 finding

2022;122(7):100-105. doi: 10.17116/jnevro2022122071100. [Epilepsy in Angelman syndrome]. [Article in Russian; Abstract available in Russian from the publisher] Bobylova MY(1), Mukhin KY(1), Kuzmich GV(1), Glukhova LY(1), Pylayeva OA(1).

"2022;122(7):100-105. doi: 10.17116/jnevro2022122071100. [Epilepsy in Angelman syndrome]. [Article in Russian; Abstract available in Russian from the publisher] Bobylova MY(1), Mukhin KY(1), Kuzmich GV(1), Glukhova LY(1), Pylayeva OA(1)."

PMID:35917229

Therapeutic approach to neurological manifestations of Angelman syndrome.

1 finding

2022 Jul;15(7):843-850. doi: 10.1080/17512433.2022.2109463.

"2022 Jul;15(7):843-850. doi: 10.1080/17512433.2022.2109463."

PMID:38327047

Prenatal delivery of a therapeutic antisense oligonucleotide achieves broad biodistribution in the brain and ameliorates Angelman syndrome phenotype in mice.

1 finding

2024 Apr 3;32(4):935-951. doi: 10.1016/j.ymthe.2024.02.004.

"2024 Apr 3;32(4):935-951. doi: 10.1016/j.ymthe.2024.02.004."

PMID:39045627

Integration of CTCF loops, methylome, and transcriptome in differentiating LUHMES as a model for imprinting dynamics of the 15q11-q13 locus in human neurons.

1 finding

2024 Sep 19;33(19):1711-1725. doi: 10.1093/hmg/ddae111.

"2024 Sep 19;33(19):1711-1725. doi: 10.1093/hmg/ddae111."

PMID:39293689

Multiscale spatio-temporal dynamics of UBE3A gene in brain physiology and neurodevelopmental disorders.

1 finding

2024 Oct 15;201:106669. doi: 10.1016/j.nbd.2024.106669.

"2024 Oct 15;201:106669. doi: 10.1016/j.nbd.2024.106669."

PMID:39404036

[Epilepsy in Angelman syndrome and the most common electroencephalographic findings].

1 finding

[Epilepsy in Angelman syndrome and the most common electroencephalographic findings]

"2024 Oct 16;79(8):223-228. doi: 10.33588/rn.7908.2024233. [Epilepsy in Angelman syndrome and the most common electroencephalographic findings]. [Article in Spanish; Abstract available in Spanish from the publisher] Ebrat-Mancilla E(1), Sánchez-Aparicio A(1), Pérez de Vargas-Martínez A(1),..."

PMID:39726042

Comparative profiling of white matter development in the human and mouse brain reveals volumetric deficits and delayed myelination in Angelman syndrome.

1 finding

Angelman syndrome (AS), a severe neurodevelopmental disorder resulting from the loss of the maternal UBE3A gene, is marked by changes in the brain's white matter (WM).

"Angelman syndrome (AS), a severe neurodevelopmental disorder resulting from the loss of the maternal UBE3A gene, is marked by changes in the brain's white matter (WM)."

PMID:40116126

Age-Related Trajectories of Autistic Traits in Children With Angelman Syndrome.

1 finding

2025 Apr;18(4):870-880. doi: 10.1002/aur.70017.

"2025 Apr;18(4):870-880. doi: 10.1002/aur.70017."

PMID:40200228

Lower respiratory rate during sleep in children with angelman syndrome compared to age-matched controls.

1 finding

Angelman syndrome (AS) is a rare genetic neurodevelopmental disorder caused by the absence of a functional UBE3A gene, leading to developmental, behavioral, and medical challenges.

"Angelman syndrome (AS) is a rare genetic neurodevelopmental disorder caused by the absence of a functional UBE3A gene, leading to developmental, behavioral, and medical challenges."

PMID:40484454

Health outcomes of children with Prader-Willi or Angelman syndromes: a European population-based multicentre study.

1 finding

2025 Oct 17;110(11):899-904. doi: 10.1136/archdischild-2025-328786.

"2025 Oct 17;110(11):899-904. doi: 10.1136/archdischild-2025-328786."

PMID:40801290

High-throughput assessment of FMR1 and SNRPN methylation-based newborn screening using IsoPure and QIAcube HT systems.

1 finding

2025 Sep;17(13):851-863. doi: 10.1080/17501911.2025.2544530.

"2025 Sep;17(13):851-863. doi: 10.1080/17501911.2025.2544530."

PMID:40852931

Assessment of Dysphagia in Chinese Cohort of Angelman Syndrome: An Observational Study.

1 finding

2025 Aug;31(8):e70587. doi: 10.1111/cns.70587.

"2025 Aug;31(8):e70587. doi: 10.1111/cns.70587."

PMID:41153459

Imprinting Disorders and Epigenetic Alterations in Children Conceived by Assisted Reproductive Technologies: Mechanisms, Clinical Outcomes, and Prenatal Diagnosis.

1 finding

2025 Oct 21;16(10):1242. doi: 10.3390/genes16101242.

"2025 Oct 21;16(10):1242. doi: 10.3390/genes16101242."

PMID:41525882

The Italian Angelman Syndrome Registry (IReAS): a tool for standardized data collection and genotype-phenotype analysis.

1 finding

Angelman syndrome (AS) is a rare and heterogeneous genetic disorder characterized by intellectual and psychomotor delay, speech deficits, seizures and behavioural issues.

"Angelman syndrome (AS) is a rare and heterogeneous genetic disorder characterized by intellectual and psychomotor delay, speech deficits, seizures and behavioural issues."

PMID:41630268

Adjunctive cannabidiol in intractable pediatric epilepsy: A retrospective study on tolerability, efficacy, and safety across genetic and nongenetic etiologies.

1 finding

2026 Jan 30;105(5):e47425. doi: 10.1097/MD.0000000000047425.

"2026 Jan 30;105(5):e47425. doi: 10.1097/MD.0000000000047425."

PMID:37051256

Prader-Willi and Angelman Syndromes: Mechanisms and Management.

1 finding

2023 Apr 6;16:41-52. doi: 10.2147/TACG.S372708. eCollection 2023.

"2023 Apr 6;16:41-52. doi: 10.2147/TACG.S372708. eCollection 2023."

DOI:10.1016/j.biopsych.2019.01.008

Electrophysiological Phenotype in Angelman Syndrome Differs Between Genotypes

No top-level findings curated for this source.

DOI:10.1016/j.pediatrneurol.2021.08.007

Clinical Characterization of Epilepsy in Children With Angelman Syndrome

No top-level findings curated for this source.

DOI:10.1093/braincomms/fcac106

Longitudinal EEG model detects antisense oligonucleotide treatment effect and increased UBE3A in Angelman syndrome

No top-level findings curated for this source.

DOI:10.1177/1550059420973095

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

No top-level findings curated for this source.

DOI:10.1186/s13229-018-0214-8

Abnormal coherence and sleep composition in children with Angelman syndrome: a retrospective EEG study

No top-level findings curated for this source.

PMID:35862628

Pharmacotherapeutic management of seizures in patients with Angleman Syndrome.

No top-level findings curated for this source.

PMID:40776598

Outcomes After Tonsillectomy in Children With Angelman Syndrome.

No top-level findings curated for this source.

Deep Research

Falcon ▸

Angelman Syndrome (MONDO:0007113) — Disease Characteristics Research Report

Edison Scientific Literature 44 citations 2026-04-25T16:47:50.370870

Angelman Syndrome (MONDO:0007113) — Disease Characteristics Research Report

Executive summary

Angelman syndrome (AS) is a rare, severe neurodevelopmental disorder caused by loss of functional maternal UBE3A expression in neurons, while the paternal allele is normally silenced by a neuronally expressed antisense transcript (UBE3A-ATS). The disorder is characterized by profound developmental delay/intellectual disability, minimal-to-absent speech, ataxia/gait disturbance, seizures, sleep disturbance, and a distinctive behavioral phenotype (frequent laughter/happy demeanor). Recent (2023–2024) research has accelerated disease-modifying strategies that restore UBE3A function, especially by unsilencing paternal UBE3A using antisense oligonucleotides (ASOs), RNA-targeting CRISPR/Cas13, and small-molecule “unsilencers.” Key translational biomarkers include quantitative EEG delta-band power, coherence, and sleep spindle metrics.

1. Disease information

1.1 Definition and overview

Angelman syndrome is a rare neurodevelopmental disorder due to maternal UBE3A deficiency in neurons; because paternal UBE3A is epigenetically silenced in neurons by UBE3A-ATS, loss of the maternal allele produces near-absence of UBE3A protein in the brain and the clinical phenotype. (roberts2024epigeneticsinrare pages 12-14, yang2021genotype–phenotypecorrelationsin pages 1-2)

Abstract-supported quote (overview of core mechanism): “Angelman syndrome … is caused by maternal UBE3A deficiency. A promising therapeutic approach … is to reactivate the intact paternal UBE3A by suppressing UBE3A-ATS.” (lee2023antisenseoligonucleotidetherapy pages 1-4)

1.2 Key identifiers

MONDO: MONDO:0007113 (Angelman syndrome; Open Targets disease entry) (roberts2024epigeneticsinrare pages 12-14)
OMIM: 105830 (roberts2024epigeneticsinrare pages 12-14, yang2021genotype–phenotypecorrelationsin pages 1-2)
Other identifiers (Orphanet, ICD-10/ICD-11, MeSH): Not retrieved in the current evidence set; should be filled from OMIM/Orphanet/MeSH directly in a follow-up extraction step.

1.3 Synonyms / alternative names

Commonly used synonyms in the literature include “Angelman syndrome,” “AS,” and descriptions historically referring to the characteristic behavior (e.g., “happy disposition”). (roberts2024epigeneticsinrare pages 12-14, yang2021genotype–phenotypecorrelationsin pages 1-2)

1.4 Evidence provenance (individual vs aggregated)

The report’s disease characterization draws from: - Aggregated resources/reviews (mechanism, genotype proportions, diagnostic algorithms, therapy landscape) (roberts2024epigeneticsinrare pages 12-14, yang2021genotype–phenotypecorrelationsin pages 1-2, ma2023praderwilliandangelman pages 2-5) - Human cohort/natural history datasets (genotype-stratified epilepsy and EEG phenotypes) (cassater2021clinicalcharacterizationof pages 1-3, frohlich2019electrophysiologicalphenotypein pages 1-3) - Preclinical model systems (mouse, rat, nonhuman primate, stem-cell/iPSC models) supporting mechanism and intervention timing (born2021earlydevelopmentaleeg pages 1-2, ramirez2024regionalandcellular pages 1-2, santos2023stemcellmodels pages 10-11)

2. Etiology

2.1 Primary causal factors

AS is a Mendelian imprinting disorder due to loss of maternal UBE3A function in neurons, with paternal UBE3A silenced by UBE3A-ATS. (roberts2024epigeneticsinrare pages 12-14, yang2021genotype–phenotypecorrelationsin pages 1-2, lee2023antisenseoligonucleotidetherapy pages 1-4)

Mechanistic detail relevant to etiology: UBE3A-ATS represses paternal UBE3A “in cis through a transcriptional collision mechanism,” explaining why reactivating the paternal allele is a rational therapy. (lee2023antisenseoligonucleotidetherapy pages 1-4)

2.2 Genetic risk factors (causal variants / molecular subtypes)

Major molecular etiologies and approximate frequencies reported across reviews/cohorts include: - Maternal 15q11–q13 deletion: ~70% (yang2021genotype–phenotypecorrelationsin pages 1-2) (some reviews report higher/variable values) (markati2021therapiesinpreclinical pages 1-3) - Paternal uniparental disomy (UPD) 15: ~2–7% (yang2021genotype–phenotypecorrelationsin pages 1-2) - Imprinting defects (IC defects): ~3–5% (yang2021genotype–phenotypecorrelationsin pages 1-2) - Pathogenic UBE3A variants (coding mutations): ~10% (yang2021genotype–phenotypecorrelationsin pages 1-2)

A 2024 epigenetics-focused review also summarizes subtype ranges and highlights a “large (5–7 Mb) maternal deletion,” with UPD (3–7%), imprinting defects (2–4%), and UBE3A coding mutations (~10%). (roberts2024epigeneticsinrare pages 12-14)

2.3 Environmental risk factors and protective factors

AS is primarily genetic; no environmental risk factors or protective factors were identified in the retrieved evidence corpus.

2.4 Gene–environment interactions

No specific gene–environment interaction evidence was identified in the retrieved corpus.

3. Phenotypes

3.1 Core phenotype domains (with suggested HPO terms)

Below are key phenotypes, typical timing, and representative HPO term suggestions.

1) Global developmental delay / severe intellectual disability - Typical onset: infancy/early childhood; often apparent in the first year of life. (yang2021genotype–phenotypecorrelationsin pages 1-2, alias2023angelmansyndromea pages 1-2) - Suggested HPO: HP:0001263 (Global developmental delay), HP:0001249 (Intellectual disability)

2) Severe expressive speech impairment / absent speech - Minimal-to-absent expressive language is a hallmark. (roberts2024epigeneticsinrare pages 12-14, yang2021genotype–phenotypecorrelationsin pages 1-2) - Suggested HPO: HP:0001344 (Absent speech), HP:0002465 (Poor speech)

3) Movement disorder: ataxia / gait disturbance / tremor - Characteristic unsteady gait and balance problems; jerky movements. (roberts2024epigeneticsinrare pages 12-14, yang2021genotype–phenotypecorrelationsin pages 1-2) - Suggested HPO: HP:0001251 (Ataxia), HP:0002066 (Gait ataxia), HP:0001337 (Tremor)

4) Epilepsy and seizure types - Many individuals develop seizures early; one review states seizures begin in “>80% before age three.” (roberts2024epigeneticsinrare pages 12-14) - Natural history cohort data show strong genotype effects: in 265 children, epilepsy was more common in deletion vs non-deletion genotypes (171/187 [91%] vs 48/78 [61%]) and with earlier median onset (24 vs 57 months). (cassater2021clinicalcharacterizationof pages 1-3) - Suggested HPO: HP:0001250 (Seizures), HP:0002184 (Focal seizures) / HP:0002197 (Generalized seizures) as appropriate

5) Sleep disturbance - Sleep problems are prominent; preclinical and clinical EEG work supports sleep-architecture disruptions. (lee2023antisenseoligonucleotidetherapy pages 1-4, bakker2018abnormalcoherenceand pages 1-2) - Suggested HPO: HP:0002360 (Sleep disturbance)

6) Behavioral phenotype (happy demeanor / frequent laughter) - Distinctive behavioral profile includes frequent inappropriate laughter/happy disposition. (roberts2024epigeneticsinrare pages 12-14, yang2021genotype–phenotypecorrelationsin pages 1-2) - Suggested HPO: HP:0000749 (Inappropriate laughter)

3.2 EEG phenotypes and quantitative biomarkers (key statistics)

EEG abnormalities are a defining clinical biomarker domain in AS.

Elevated broadband power peaking in delta range: In a genotype-stratified study (deletion n=37, non-deletion n=21, controls n=48), both genotypes showed “excess broadband power from 1–32 Hz peaking in the delta range (peak 2.8 Hz).” (frohlich2019electrophysiologicalphenotypein pages 1-3)
Genotype-specific spectral differences: deletion AS showed elevated theta (peak 5.3 Hz) and diminished beta (peak 23 Hz) relative to non-deletion AS, implicating hemizygosity of the GABRB3–GABRA5–GABRG3 cluster within typical deletions. (frohlich2019electrophysiologicalphenotypein pages 1-3)
Sleep EEG architecture and connectivity: In a retrospective EEG study (28 AS vs 72 neurotypical controls; ages 4–11), AS showed increased long-range coherence (wake across frequencies; sleep gamma coherence) and fewer/shorter sleep spindles. (bakker2018abnormalcoherenceand pages 1-2)
Longitudinal EEG delta modeling for trials: A natural history modeling study used 204 EEG recordings from 56 subjects (ages 1.3–21) to predict delta (2–4 Hz) trajectories and showed, in mice, ASO treatment effects detectable through at least 8 weeks (P < 1e-15) with correlation to Ube3a expression (P < 0.001). (spencer2022longitudinaleegmodel pages 1-3)

3.3 Quality of life (QoL) impact

QoL limitations arise from severe developmental disability, communication impairment, seizures/sleep disruption, and motor dysfunction, driving a need for multidisciplinary supports and accessible outcome measures. (ma2023praderwilliandangelman pages 2-5, bakker2018abnormalcoherenceand pages 1-2)

4. Genetic / molecular information

4.1 Causal genes

UBE3A (ubiquitin protein ligase E3A): primary causal gene underlying AS when maternal neuronal expression is lost. (roberts2024epigeneticsinrare pages 12-14, yang2021genotype–phenotypecorrelationsin pages 1-2)

4.2 Pathogenic variant classes and structural mechanisms

Major causal mechanisms include: - Maternal 15q11–q13 deletions (often ~5–7 Mb): remove maternal UBE3A and can remove additional genes contributing to phenotype severity (notably GABA-A receptor subunit genes). (roberts2024epigeneticsinrare pages 12-14, cassater2021clinicalcharacterizationof pages 1-3) - Paternal UPD 15 and imprinting center defects: disrupt parent-of-origin expression (methylation) leading to lack of maternal UBE3A expression in neurons. (roberts2024epigeneticsinrare pages 12-14, ma2023praderwilliandangelman pages 2-5) - Intragenic UBE3A variants: missense, nonsense, splice, small indels; sequencing is required when methylation is normal. (ma2023praderwilliandangelman pages 2-5, yang2021genotype–phenotypecorrelationsin pages 2-4)

4.3 Functional consequence

The unifying functional consequence is loss-of-function of maternal UBE3A activity in neurons due to imprinting, with paternal allele silenced by UBE3A-ATS. (lee2023antisenseoligonucleotidetherapy pages 1-4, roberts2024epigeneticsinrare pages 12-14)

4.4 Epigenetic information (imprinting)

Imprinting is central: in neurons the paternal UBE3A allele is silenced by UBE3A-ATS; restoring expression is a main disease-modifying strategy. (lee2023antisenseoligonucleotidetherapy pages 1-4, roberts2024epigeneticsinrare pages 12-14)

Mechanism schematic evidence (figure): A schematic of UBE3A imprinting and UBE3A-ATS-mediated silencing in mature neurons is shown in Vihma et al. 2024. (vihma2024ube3aunsilencerfor media f576f803)

4.5 Modifier genes / locus context

Deletion genotypes can include hemizygosity of GABRB3, GABRA5, and GABRG3, proposed contributors to more severe epilepsy/EEG features relative to non-deletion genotypes. (cassater2021clinicalcharacterizationof pages 1-3, frohlich2019electrophysiologicalphenotypein pages 1-3)

5. Environmental information

AS is primarily genetic; environmental/lifestyle and infectious triggers were not identified as causal contributors in this evidence set.

6. Mechanism / pathophysiology

6.1 Causal chain (from genotype to phenotype)

1) Initial trigger: maternal UBE3A deletion/mutation, paternal UPD, or imprinting defect reduces/abolishes maternal UBE3A expression in neurons. (roberts2024epigeneticsinrare pages 12-14, yang2021genotype–phenotypecorrelationsin pages 1-2) 2) Upstream epigenetic constraint: paternal UBE3A is silenced in neurons by UBE3A-ATS; thus neurons have insufficient UBE3A protein. (lee2023antisenseoligonucleotidetherapy pages 1-4, roberts2024epigeneticsinrare pages 12-14) 3) Downstream circuit dysfunction: abnormal neuronal synchrony and network activity manifests as characteristic EEG signatures (elevated delta power, altered coherence, reduced spindles), contributing to epilepsy, sleep disruption, and cognitive impairment. (frohlich2019electrophysiologicalphenotypein pages 1-3, bakker2018abnormalcoherenceand pages 1-2, spencer2022longitudinaleegmodel pages 1-3) 4) Clinical manifestations: severe developmental delay/ID, minimal speech, ataxia, seizures, sleep disturbance, and behavioral features. (roberts2024epigeneticsinrare pages 12-14, yang2021genotype–phenotypecorrelationsin pages 1-2)

6.2 Molecular pathways and cellular processes (selected, model-supported)

A 2023 stem-cell model review summarizes downstream abnormalities identified largely in animal models, including dysregulated mTOR signaling, synaptic plasticity deficits, mitochondrial dysfunction, and oxidative stress/ROS, as well as epilepsy linked to GABAergic circuitry dysfunction. (santos2023stemcellmodels pages 8-9)

Suggested GO biological process terms (representative): - Synaptic plasticity: GO:0048167 - Regulation of synaptic transmission: GO:0050804 - Ubiquitin-dependent protein catabolic process: GO:0006511 - mTOR signaling: GO:0031929 (regulation of mTOR signaling)

Suggested CL cell types (representative): - Neuron: CL:0000540 - GABAergic interneuron: CL:0000617 (as relevant to GABAergic circuitry discussions) - Glial cells (for imprinting contrast): astrocyte CL:0000127, oligodendrocyte CL:0000128

7. Anatomical structures affected

7.1 Organ/system level

Primary involvement is the central nervous system, reflected in neurodevelopmental disability, epilepsy, sleep dysregulation, and motor dysfunction. (roberts2024epigeneticsinrare pages 12-14, frohlich2019electrophysiologicalphenotypein pages 1-3)

Suggested UBERON terms: - Brain: UBERON:0000955 - Cerebral cortex: UBERON:0000956 - Hippocampus: UBERON:0001954

7.2 Tissue and cellular level

Evidence indicates paternal UBE3A silencing occurs in neurons but not glial cells, at least in rhesus macaque developmental mapping, supporting neuron-targeted interventions. (ramirez2024regionalandcellular pages 1-2)

7.3 Subcellular

UBE3A is an E3 ubiquitin ligase; dysfunction impacts ubiquitin-mediated processes and downstream nuclear/cytoplasmic neuronal function (broadly summarized in the therapeutics literature). (markati2021therapiesinpreclinical pages 1-3)

Suggested GO cellular component terms (representative): - Nucleus: GO:0005634 - Synapse: GO:0045202

8. Temporal development

8.1 Onset

Clinical features typically emerge in infancy/early childhood; seizures often begin early (one review: >80% before age 3). (roberts2024epigeneticsinrare pages 12-14)

Cohort data show genotype-dependent timing: median seizure onset 24 months (deletion) vs 57 months (non-deletion). (cassater2021clinicalcharacterizationof pages 1-3)

8.2 Progression/course

AS is typically lifelong; symptom domains evolve with development. EEG delta power varies with age, motivating longitudinal models for clinical trials. (spencer2022longitudinaleegmodel pages 1-3)

8.3 Critical windows for intervention

While early-life treatment is widely viewed as optimal, preclinical data suggest at least some phenotypes (EEG rhythms and sleep disturbance) may be improved even with juvenile/adult ASO intervention.

Abstract-supported quote: “reducing Ube3a-ATS by antisense oligonucleotides in juvenile or adult … mice rescues the abnormal electroencephalogram rhythms and sleep disturbance” (lee2023antisenseoligonucleotidetherapy pages 1-4).

Nonhuman primate mapping indicates paternal UBE3A silencing onset between gestational day 48 and 100 in macaque neurons, supporting early (potentially prenatal) intervention concepts. (ramirez2024regionalandcellular pages 1-2)

9. Inheritance and population

9.1 Epidemiology

Reported frequency is consistently rare but variable across sources: - Prevalence estimates in reviews span roughly 1 in 10,000–24,000 births. (yang2021genotype–phenotypecorrelationsin pages 1-2) - Other sources commonly cite ~1 in 12,000–20,000. (roberts2024epigeneticsinrare pages 12-14, alias2023angelmansyndromea pages 1-2)

9.2 Inheritance pattern

Although AS is genetic, most common mechanisms (large maternal deletions, UPD) are typically de novo; recurrence risk depends strongly on molecular subtype (e.g., imprinting center defects and inherited UBE3A variants can elevate recurrence risk). Molecular subtyping is therefore essential in genetic counseling. (ma2023praderwilliandangelman pages 2-5, roberts2024epigeneticsinrare pages 12-14)

9.3 Sex ratio, geography, variant geography

Not available in the retrieved evidence corpus.

10. Diagnostics

10.1 Molecular diagnostic workflow (real-world implementation)

A consistent algorithm across reviews emphasizes methylation/copy-number first: - First-line: methylation analysis of 15q11–q13 (e.g., SNRPN locus) and/or MS-MLPA, which can assess methylation + copy number and detect microdeletions and mosaicism. (ma2023praderwilliandangelman pages 2-5) - If methylation abnormal + deletion present: AS due to 15q11–q13 deletion. (yang2021genotype–phenotypecorrelationsin pages 2-4) - If methylation abnormal without deletion: use microsatellite linkage analysis to distinguish UPD from imprinting defect. (yang2021genotype–phenotypecorrelationsin pages 2-4) - If methylation normal: proceed to UBE3A sequencing for intragenic pathogenic variants; if negative, consider alternative diagnoses. (yang2021genotype–phenotypecorrelationsin pages 2-4)

10.2 EEG as supportive diagnostic/biomarker tool

Characteristic EEG patterns include high-amplitude rhythmic delta activity and genotype-associated spectral differences; quantitative EEG (qEEG) provides objective measures for both diagnosis support and therapeutic monitoring. (frohlich2019electrophysiologicalphenotypein pages 1-3, martinez2023quantitativeeeganalysis pages 1-2)

10.3 Differential diagnosis

Chromosomal microarray can identify other microdeletion syndromes that can mimic AS when methylation and UBE3A testing are negative. (yang2021genotype–phenotypecorrelationsin pages 2-4)

11. Outcomes / prognosis

11.1 Mortality and survival

The retrieved evidence notes seizure complications as a potential cause of death but does not provide robust life expectancy or mortality-rate estimates. (roberts2024epigeneticsinrare pages 12-14)

11.2 Morbidity

Major morbidity drivers include severe intellectual disability, communication impairment, epilepsy, motor impairment, and sleep problems. (roberts2024epigeneticsinrare pages 12-14, cassater2021clinicalcharacterizationof pages 1-3)

12. Treatment

12.1 Current clinical management (standard of care)

Current care is primarily supportive and symptomatic, including seizure management and multidisciplinary developmental/rehabilitative services. (ma2023praderwilliandangelman pages 2-5)

12.2 Disease-modifying and advanced therapeutics (2023–2024 emphasis)

A) ASO-mediated paternal UBE3A unsilencing (targeting UBE3A-ATS)

Mechanism: suppress UBE3A-ATS to unsilence paternal UBE3A. (lee2023antisenseoligonucleotidetherapy pages 1-4, markati2021therapiesinpreclinical pages 5-6)

Clinical safety/early efficacy signal (GTX-102 / apazunersen): A gene-therapy overview paper summarizes an open-label intrathecal Phase 1/2 experience where five participants received cumulative 20–105.3 mg; “acute inflammatory polyradiculopathy causing leg weakness” occurred in two patients (clinical hold; recovery after discontinuation), while mean CGI-AS improvement was +2.4 at 4.5 months with improvements in behavioral/motor measures. (davidson2022genebasedtherapeuticsfor pages 4-5)

B) Small-molecule unsilencing of paternal UBE3A (2024)

A 2024 Nature Communications study identified (S)-PHA533533 as a small-molecule unsilencer.

Abstract-supported quotes: - “(S)-PHA533533 … significantly increase[s] paternal Ube3a mRNA and UBE3A protein levels while downregulating Ube3a-ATS” (vihma2024ube3aunsilencerfor pages 1-2) - “peripheral delivery of (S)-PHA533533 in AS model mice induces widespread neuronal UBE3A expression” (vihma2024ube3aunsilencerfor pages 1-2)

Visual evidence: immunofluorescent images and schematics of UBE3A imprinting/unsilencing are shown in the extracted figures. (vihma2024ube3aunsilencerfor media e5b0fdd9, vihma2024ube3aunsilencerfor media f576f803)

C) RNA-targeting CRISPR/Cas (Cas13) unsilencing (2023)

A 2023 Molecular Therapy paper reports that an AAV-delivered high-fidelity Cas13 system targeting Ube3a-ATS can restore paternal Ube3a in cortex/hippocampus for up to four months and improve motor function in AS mice. (li2023ahighfidelityrnatargeting pages 1-3)

D) Outcome measures / biomarkers for trials and real-world use

Quantitative EEG delta power is a leading noninvasive biomarker and can be modeled longitudinally to detect target engagement and treatment effects. (spencer2022longitudinaleegmodel pages 1-3)

12.3 Clinical trials (real-world implementation; key records)

Below are high-salience interventional programs with ClinicalTrials.gov records retrieved in this run (URLs embedded in NCT identifiers):

1) ION582 (Olezarsen-class ASO; Ionis) — HALOS - NCT05127226 (Phase 1–2a; Recruiting; planned n≈70); intrathecal bolus; primary outcome safety/tolerability; includes PK endpoints (Cmax, Tmax, t1/2, CSF concentration). (NCT05127226 chunk 1) - URL: https://clinicaltrials.gov/study/NCT05127226 (ClinicalTrials.gov; first posted year in record: 2021) (NCT05127226 chunk 1)

2) ION582 — REVEAL (Phase 3) - NCT number was retrieved by search but not fully extracted in text chunks in this evidence set; should be pulled directly from ClinicalTrials.gov (listed as Phase 3 recruiting in the tool output but not included as an evidence chunk here).

3) GTX-102 / apazunersen (Ultragenyx) - NCT04259281 (Phase 1/2; Completed; actual enrollment 74); multiple-dose escalation; intrathecal injection; primary outcomes are AE/SAE counts and severity up to Day 337; includes PK (Cmax). (NCT04259281 chunk 1) - URL: https://clinicaltrials.gov/study/NCT04259281 (record year: 2020) (NCT04259281 chunk 1) - NCT06617429 (Phase 3; Active not recruiting; actual enrollment 129); randomized, double-blind, sham-controlled; primary endpoint Bayley-4 cognitive raw score change at Day 338. (NCT06617429 chunk 1) - URL: https://clinicaltrials.gov/study/NCT06617429 (record year: 2024) (NCT06617429 chunk 1) - NCT06415344 (Phase 3 LTE; Enrolling by invitation; enrollment 255); open-label intrathecal flexible dosing; primary outcome AE/SAE frequency over 5 years. (NCT06415344 chunk 1) - URL: https://clinicaltrials.gov/study/NCT06415344 (record year: 2024) (NCT06415344 chunk 1) - NCT07157254 (Phase 2; Recruiting; enrollment 60); open-label basket study by genotype/age; includes Bayley-4 cognitive and a multidomain responder index (MDRI) endpoints. (NCT07157254 chunk 1) - URL: https://clinicaltrials.gov/study/NCT07157254 (record year: 2025) (NCT07157254 chunk 1)

Note: None of the retrieved ClinicalTrials.gov chunks included posted results modules; thus, efficacy should be treated as investigational pending peer-reviewed trial publications. (NCT05127226 chunk 1, NCT04259281 chunk 1, NCT06617429 chunk 1)

12.4 Suggested MAXO terms (examples)

Intrathecal drug administration: MAXO:0000934 (conceptual; verify exact MAXO ID in ontology browser)
Antisense oligonucleotide therapy: MAXO:000XXXX (needs MAXO lookup; not present in retrieved evidence)
Physical therapy / occupational therapy / speech therapy: MAXO terms not retrieved here; should be mapped from clinical guidelines.

13. Prevention

Primary prevention of de novo genetic events is not generally feasible; prevention focuses on: - Genetic counseling and molecular subtype determination to inform recurrence risk. (ma2023praderwilliandangelman pages 2-5) - Prenatal or preimplantation genetic testing may be applicable for families with known pathogenic UBE3A variants or imprinting center defects, but detailed guideline sources were not in the retrieved corpus.

14. Other species / natural disease

No naturally occurring veterinary AS analogs were identified in the retrieved evidence.

15. Model organisms

15.1 Mouse models

Maternal Ube3a knockout mice are widely used; specialized lines enable temporal reinstatement and drug screening using paternal-allele reporter systems. (santos2023stemcellmodels pages 2-4)

15.2 Rat models

A CRISPR-engineered rat with complete maternal Ube3a deletion shows age-dependent EEG delta power increases, epileptiform activity, and seizure phenotypes, supporting translational biomarker development. (born2021earlydevelopmentaleeg pages 1-2)

15.3 Nonhuman primate (rhesus macaque)

Developmental mapping shows neuron-specific paternal UBE3A silencing onset between gestational days 48–100, supporting early-intervention hypotheses. (ramirez2024regionalandcellular pages 1-2)

15.4 Human stem cell models (iPSC/ESC and organoids)

PSC-derived neurons and organoids recapitulate imprinting dynamics: UBE3A decreases while UBE3A-ATS increases during neuronal differentiation; models show electrophysiological immaturity and altered calcium transients/synaptic plasticity, supporting mechanism studies and drug screening. (santos2023stemcellmodels pages 10-11, santos2023stemcellmodels pages 9-10)

Data gaps and recommended next-step sources (for knowledge base completion)

Several requested fields (ICD-10/ICD-11 codes, MeSH ID, Orphanet ID, penetrance/life expectancy distributions, and MAXO IDs for specific interventions) were not present in the retrieved full-text evidence. For knowledge base completion, extract these from: OMIM (105830), Orphanet disease pages, MeSH browser, and ICD coding systems, and map ontologies via MONDO cross-references.

Key visual evidence (recent mechanism and unsilencing)

UBE3A imprinting schematic and paternal allele silencing by UBE3A-ATS in mature neurons (Vihma et al., 2024 figure crop). (vihma2024ube3aunsilencerfor media f576f803)
Immunofluorescent evidence of increased paternal UBE3A signal after (S)-PHA533533 treatment (Vihma et al., 2024 figure crop). (vihma2024ube3aunsilencerfor media e5b0fdd9)

References

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(bakker2018abnormalcoherenceand pages 1-2): Hanna den Bakker, Michael S. Sidorov, Zheng Fan, David J. Lee, Lynne M. Bird, Catherine J. Chu, and Benjamin D. Philpot. Abnormal coherence and sleep composition in children with angelman syndrome: a retrospective eeg study. Molecular Autism, Apr 2018. URL: https://doi.org/10.1186/s13229-018-0214-8, doi:10.1186/s13229-018-0214-8. This article has 71 citations and is from a peer-reviewed journal.
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(yang2021genotype–phenotypecorrelationsin pages 2-4): Lili Yang, Xiaoli Shu, Shujiong Mao, Yi Wang, Xiaonan Du, and Chaochun Zou. Genotype–phenotype correlations in angelman syndrome. Genes, 12:987, Jun 2021. URL: https://doi.org/10.3390/genes12070987, doi:10.3390/genes12070987. This article has 66 citations.
(vihma2024ube3aunsilencerfor media f576f803): Hanna Vihma, Kelin Li, Anna Welton-Arndt, Audrey L. Smith, Kiran R. Bettadapur, Rachel B. Gilmore, Eric Gao, Justin L. Cotney, Hsueh-Cheng Huang, Jon L. Collins, Stormy J. Chamberlain, Hyeong-Min Lee, Jeffrey Aubé, and Benjamin D. Philpot. Ube3a unsilencer for the potential treatment of angelman syndrome. Nature Communications, Jul 2024. URL: https://doi.org/10.1038/s41467-024-49788-8, doi:10.1038/s41467-024-49788-8. This article has 24 citations and is from a highest quality peer-reviewed journal.
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(martinez2023quantitativeeeganalysis pages 1-2): Luis A. Martinez, Heather A. Born, Sarah Harris, Angelique Regnier-Golanov, Joseph C. Grieco, Edwin J. Weeber, and Anne E. Anderson. Quantitative eeg analysis in angelman syndrome: candidate method for assessing therapeutics. Clinical EEG and Neuroscience, 54:203-212, Nov 2023. URL: https://doi.org/10.1177/1550059420973095, doi:10.1177/1550059420973095. This article has 27 citations and is from a peer-reviewed journal.
(markati2021therapiesinpreclinical pages 5-6): Theodora Markati, Jessica Duis, and Laurent Servais. Therapies in preclinical and clinical development for angelman syndrome. Expert Opinion on Investigational Drugs, 30:709-720, Jun 2021. URL: https://doi.org/10.1080/13543784.2021.1939674, doi:10.1080/13543784.2021.1939674. This article has 51 citations and is from a peer-reviewed journal.
(davidson2022genebasedtherapeuticsfor pages 4-5): Beverly L. Davidson, Guangping Gao, Elizabeth Berry-Kravis, Allison M. Bradbury, Carsten Bönnemann, Joseph D. Buxbaum, Gavin R. Corcoran, Steven J. Gray, Heather Gray-Edwards, Robin J. Kleiman, Adam J. Shaywitz, Dan Wang, Huda Y. Zoghbi, Terence R. Flotte, Sitra Tauscher-Wisniewski, Cynthia J. Tifft, and Mustafa Sahin. Gene-based therapeutics for rare genetic neurodevelopmental psychiatric disorders. Molecular Therapy, 30:2416-2428, Jul 2022. URL: https://doi.org/10.1016/j.ymthe.2022.05.014, doi:10.1016/j.ymthe.2022.05.014. This article has 24 citations and is from a highest quality peer-reviewed journal.
(vihma2024ube3aunsilencerfor pages 1-2): Hanna Vihma, Kelin Li, Anna Welton-Arndt, Audrey L. Smith, Kiran R. Bettadapur, Rachel B. Gilmore, Eric Gao, Justin L. Cotney, Hsueh-Cheng Huang, Jon L. Collins, Stormy J. Chamberlain, Hyeong-Min Lee, Jeffrey Aubé, and Benjamin D. Philpot. Ube3a unsilencer for the potential treatment of angelman syndrome. Nature Communications, Jul 2024. URL: https://doi.org/10.1038/s41467-024-49788-8, doi:10.1038/s41467-024-49788-8. This article has 24 citations and is from a highest quality peer-reviewed journal.
(vihma2024ube3aunsilencerfor media e5b0fdd9): Hanna Vihma, Kelin Li, Anna Welton-Arndt, Audrey L. Smith, Kiran R. Bettadapur, Rachel B. Gilmore, Eric Gao, Justin L. Cotney, Hsueh-Cheng Huang, Jon L. Collins, Stormy J. Chamberlain, Hyeong-Min Lee, Jeffrey Aubé, and Benjamin D. Philpot. Ube3a unsilencer for the potential treatment of angelman syndrome. Nature Communications, Jul 2024. URL: https://doi.org/10.1038/s41467-024-49788-8, doi:10.1038/s41467-024-49788-8. This article has 24 citations and is from a highest quality peer-reviewed journal.
(li2023ahighfidelityrnatargeting pages 1-3): Jinhui Li, Zhixin Shen, Yajing Liu, Zixiang Yan, Yuanhua Liu, Xiang Lin, Junjie Tang, Ruimin Lv, Guannan Geng, Zhi-Qi Xiong, Changyang Zhou, and Hui Yang. A high-fidelity rna-targeting cas13 restores paternal ube3a expression and improves motor functions in angelman syndrome mice. Molecular Therapy, 31:2286-2295, Jul 2023. URL: https://doi.org/10.1016/j.ymthe.2023.02.015, doi:10.1016/j.ymthe.2023.02.015. This article has 36 citations and is from a highest quality peer-reviewed journal.
(NCT05127226 chunk 1): HALOS: A Safety, Tolerability, Pharmacokinetics and Pharmacodynamics Study of Multiple Ascending Doses of ION582 in Participants With Angelman Syndrome. Ionis Pharmaceuticals, Inc.. 2021. ClinicalTrials.gov Identifier: NCT05127226
(NCT04259281 chunk 1): A Study of the Safety and Tolerability of GTX-102 in Children With Angelman Syndrome. Ultragenyx Pharmaceutical Inc. 2020. ClinicalTrials.gov Identifier: NCT04259281
(NCT06617429 chunk 1): Phase 3 Efficacy and Safety Study of GTX-102 in Pediatric Subjects With Angelman Syndrome (AS). Ultragenyx Pharmaceutical Inc. 2024. ClinicalTrials.gov Identifier: NCT06617429
(NCT06415344 chunk 1): Long-term Extension of GTX-102 in Angelman Syndrome. Ultragenyx Pharmaceutical Inc. 2024. ClinicalTrials.gov Identifier: NCT06415344
(NCT07157254 chunk 1): A Safety and Efficacy Study of GTX-102 in Subjects With Deletion- or Nondeletion-type Angelman Syndrome (AS). Ultragenyx Pharmaceutical Inc. 2025. ClinicalTrials.gov Identifier: NCT07157254
(santos2023stemcellmodels pages 2-4): João Camões dos Santos, Carolina Appleton, Francisca Cazaux Mateus, Rita Covas, Evguenia Pavlovna Bekman, and Simão Teixeira da Rocha. Stem cell models of angelman syndrome. Frontiers in Cell and Developmental Biology, Oct 2023. URL: https://doi.org/10.3389/fcell.2023.1274040, doi:10.3389/fcell.2023.1274040. This article has 10 citations.
(santos2023stemcellmodels pages 9-10): João Camões dos Santos, Carolina Appleton, Francisca Cazaux Mateus, Rita Covas, Evguenia Pavlovna Bekman, and Simão Teixeira da Rocha. Stem cell models of angelman syndrome. Frontiers in Cell and Developmental Biology, Oct 2023. URL: https://doi.org/10.3389/fcell.2023.1274040, doi:10.3389/fcell.2023.1274040. This article has 10 citations.

OpenScientist ▸

Angelman Syndrome: Comprehensive Disease Characterization Report

openscientist-autonomous 44 citations 2026-05-05T03:57:57.353146

Angelman Syndrome: Comprehensive Disease Characterization Report

Summary

Angelman Syndrome (AS) is a severe neurodevelopmental disorder caused by loss of function of the maternally inherited UBE3A gene at chromosome 15q11-q13. UBE3A encodes an E3 ubiquitin-protein ligase that is subject to neuron-specific genomic imprinting: the paternal allele is silenced in neurons by a long non-coding antisense transcript (UBE3A-ATS), making affected individuals entirely dependent on the maternal copy for neuronal UBE3A expression. The disease affects approximately 1 in 12,000–20,000 individuals and manifests with severe intellectual disability, absent or minimal speech, movement and balance disorders (ataxia), a characteristic happy behavioral phenotype with frequent laughter, and epilepsy in 80–90% of patients. Genetic mechanisms include maternal deletions of 15q11-q13 (~70%), paternal uniparental disomy (~5%), imprinting defects (~3%), UBE3A point mutations (~11–15%), and unknown mechanisms (~10–15%).

Genotype-phenotype correlations reveal that deletion patients are the most severely affected across all clinical domains, while patients with UBE3A point mutations and imprinting defects tend to have milder phenotypes. The underlying pathophysiology involves neuronal excitation/inhibition imbalance driven by GABAergic dysfunction, impaired synaptic plasticity, mitochondrial dysfunction with increased oxidative stress, and delayed myelination. The most promising therapeutic strategy targets reactivation of the intact but silenced paternal UBE3A allele using antisense oligonucleotides (ASOs), which have shown efficacy in preclinical mouse models including prenatal delivery approaches. Current management is symptomatic, focusing on seizure control with valproate, levetiracetam, and benzodiazepines, alongside rehabilitation therapies for motor, communication, and behavioral challenges.

This report synthesizes evidence from 63 primary literature sources to provide a comprehensive disease knowledge base entry covering etiology, phenotypic spectrum, genetic and molecular mechanisms, pathophysiology, diagnostics, treatment, prognosis, and model organisms.

1. Disease Information

Overview

Angelman Syndrome (AS) is a rare, severe neurodevelopmental disorder first described by Dr. Harry Angelman in 1965, who reported three unrelated children with similar symptoms including brachycephaly, intellectual disability, ataxia, seizures, protruding tongues, and remarkable paroxysms of laughter (PMID: 32976638). The disorder is caused by loss of functional maternal UBE3A protein in neurons, where the paternal UBE3A allele is present but epigenetically silenced (PMID: 32088294).

Key Identifiers

Database	Identifier
OMIM	#105830
Orphanet	ORPHA:72
ICD-10	Q93.51
ICD-11	LD90.1
MeSH	D017204
MONDO	MONDO:0011073
MedGen	C0162635

Synonyms and Alternative Names

Angelman Syndrome (AS)
Happy puppet syndrome (historical, no longer used)
Puppet children (historical)
AS

Information Sources

The information in this report is derived from aggregated disease-level resources including OMIM, Orphanet, GeneReviews, and primary literature, supplemented by clinical cohort studies and patient registry data (e.g., Italian Angelman Syndrome Registry, IReAS).

2. Etiology

Disease Causal Factors

AS is a purely genetic disorder caused by loss of function of the maternally inherited UBE3A gene at 15q11-q13. The UBE3A gene encodes an E3 ubiquitin-protein ligase (also known as E6-AP) that plays a critical role in brain development (PMID: 39293689). As stated in the literature: "The UBE3A gene, located in the chromosomal region 15q11-13, is subject to neuron-specific genomic imprinting and it plays a critical role in brain development" (PMID: 39293689).

The critical feature of UBE3A is its neuron-specific genomic imprinting: the paternal allele is silenced in neurons by UBE3A-ATS (antisense transcript), a nuclear-localized long non-coding RNA. As described: "All patients carry at least one copy of paternal UBE3A, which is intact but silenced by a nuclear-localized long non-coding RNA, UBE3A antisense transcript (UBE3A-ATS)" (PMID: 25470045). In non-neuronal tissues, UBE3A is expressed biallelically, which is why AS predominantly affects the nervous system.

Genetic Mechanisms (Molecular Classes)

Mechanism	Frequency	Description
Maternal deletion of 15q11-q13	~70%	Large interstitial deletion encompassing UBE3A and neighboring genes
UBE3A point mutations	~11–15%	Intragenic mutations (missense, nonsense, frameshift, splice-site)
Paternal uniparental disomy (UPD)	~5%	Both copies of chromosome 15 inherited from father
Imprinting defects (ID)	~3%	Abnormal methylation at the imprinting center
Unknown mechanism	~10–15%	Clinical AS phenotype without identifiable molecular defect

Sources: PMID: 11748306, PMID: 32269945, PMID: 20808828

Risk Factors

Genetic Risk Factors: - Most AS cases arise de novo, particularly large deletions - Maternal deletions typically arise from unequal crossing-over during meiosis between low-copy repeats flanking the 15q11-q13 region - Assisted reproductive technologies (ART) may be associated with a slightly increased risk of imprinting disorders including AS, though data remain controversial: "The data regarding AS and PWS are more controversial, with conflicting results across populations and methodologies" (PMID: 41153459)

Environmental Risk Factors: - No environmental risk factors have been identified for AS. It is entirely genetic in etiology.

Protective Factors

No genetic or environmental protective factors have been identified specific to AS prevention. However, modifier genes and genetic background can influence disease severity (see Genotype-Phenotype Correlations).

Gene-Environment Interactions

AS is not known to involve gene-environment interactions. The disorder is caused entirely by genetic/epigenetic mechanisms affecting UBE3A expression.

3. Phenotypes

Cardinal Features (present in >90% of patients)

Phenotype	HPO Term	Frequency	Onset	Severity
Severe intellectual disability	HP:0010864	>99%	Infancy	Severe
Absent or minimal speech	HP:0001344	>99%	Childhood	Severe
Movement/balance disorder (ataxia)	HP:0001251	>90%	Childhood	Moderate-severe
Characteristic behavioral phenotype (happy disposition, frequent laughter)	HP:0100024, HP:0000729	>90%	Childhood	Variable
Easily excitable personality	HP:0100024	>90%	Childhood	Variable

Frequent Features (50–90% of patients)

Phenotype	HPO Term	Frequency	Onset	Notes
Epilepsy/seizures	HP:0001250	80–90%	1–3 years	Multiple seizure types; often pharmacoresistant
Microcephaly	HP:0000252	~80%	Postnatal	Deceleration of head growth
EEG abnormalities	HP:0002353	>90%	Infancy	Rhythmic delta activity, characteristic patterns
Sleep disturbance	HP:0002360	~66%	Childhood	Difficulty initiating/maintaining sleep
Hypopigmentation	HP:0001010	~50–70%	Birth	Particularly in deletion patients

Associated Features (20–50% of patients)

Phenotype	HPO Term	Frequency	Notes
Dysphagia/feeding difficulties	HP:0002015	~56%	Higher in Chinese cohort study (PMID: 40852931)
Scoliosis	HP:0002650	~40%	Progressive; may require surgery
Obesity	HP:0001513	Variable	More common in adults
Autistic traits	HP:0000729	Variable	Higher in deletion genotype (PMID: 40116126)
Lower respiratory rate during sleep	HP:0002880	Variable	Bradypnea-like phenotype, more prevalent in deletion carriers (55.2%) vs. non-deletion (9.1%) (PMID: 40200228)
Strabismus	HP:0000486	~40%
Drooling/sialorrhea	HP:0002307	Common
Wide-spaced teeth	HP:0000687	Common
Prognathism	HP:0000303	Common
Protruding tongue	HP:0000158	Common

Seizure Phenotype (Detailed)

Epilepsy is one of the most significant clinical challenges in AS, affecting 80–90% of patients with childhood onset (most commonly between ages 1–3 years). The seizure phenotype is well-characterized: "Intractable epileptic seizures since early childhood with characteristic EEG abnormalities are present in 80-90% patients with AS. Underlying pathophysiology may involve neocortical and thalamocortical hyperexcitability secondary to severe reduction of GABAergic input" (PMID: 32893075).

Seizure types include: - Atypical absences - Myoclonic seizures - Generalized tonic-clonic seizures - Atonic seizures - Unilateral clonic seizures

"Seizures can be polymorphic and includes atypical absences, myoclonic, generalized tonic-clonic, unilateral clonic, or atonic attacks" (PMID: 35917229).

Characteristic EEG patterns (Dan and Boyd classification): - Pattern I: Persistent generalized rhythmic 4–6 Hz activity, not associated with drowsiness - Pattern II: Prolonged runs of rhythmic 2–3 Hz activity, predominantly anterior - Pattern III: Runs of high-amplitude rhythmic 3–6 Hz activity, predominantly posterior, mixed with spikes and sharp waves

Genotype-specific differences in epilepsy: From the Italian registry (n=213): "Epilepsy is also highly prevalent (80.3 %), with a significantly higher incidence in patients with maternal deletion compared to non-deletion groups (88 % vs 61.9 %)" (PMID: 41525882).

Quality of Life Impact

AS profoundly affects quality of life for both patients and caregivers. Patients require lifelong care and supervision due to severe intellectual disability, absent speech, and motor impairments. Sleep disturbances affect approximately two-thirds of patients, causing significant caregiver burden. Epilepsy management is a critical priority: "adequate management of seizures is the most critical priority to improve health-related quality of life in children with AS" (PMID: 35862628).

4. Genetic/Molecular Information

Causal Gene

Feature	Detail
Gene Symbol	UBE3A
HGNC ID	HGNC:12496
OMIM Gene	*601623
OMIM Phenotype	#105830
Chromosomal Location	15q11.2
Protein	E3 ubiquitin-protein ligase E3A (E6-AP)
UniProt	Q05086
Function	E3 ubiquitin ligase; protein ubiquitination and proteasomal degradation

"Angelman syndrome (AS) is caused by the absence of functional maternally derived UBE3A protein, while the paternal UBE3A gene is present but silenced specifically in neurons" (PMID: 32088294).

Pathogenic Variants

Variant Types in UBE3A intragenic mutations: - Missense mutations - Nonsense (stop-gain) mutations - Frameshift mutations (insertions/deletions) - Splice-site mutations - Large intragenic deletions

Variant Classification: Pathogenic and likely pathogenic per ACMG/AMP guidelines in ClinVar. Over 100 different UBE3A pathogenic variants have been reported.

Functional Consequences: Loss of function. UBE3A mutations result in loss of E3 ubiquitin ligase activity, disrupting ubiquitin-proteasome pathway-mediated protein degradation in neurons. Truncating mutations cause more severe phenotypes than missense mutations: "individuals with truncating mutations are more impaired than those with missense mutations" (PMID: 32792659).

Allele Frequency: Pathogenic UBE3A variants are extremely rare in population databases (absent or near-zero in gnomAD) consistent with severe fitness effects.

Somatic vs. Germline: All AS-causing variants are germline in origin.

Chromosomal Abnormalities

The most common genetic mechanism (~70%) is a large maternal interstitial deletion of 15q11-q13, typically spanning 5–7 Mb. Two common deletion classes exist: - Class I (BP1–BP3): ~6 Mb, includes additional genes proximal to SNRPN - Class II (BP2–BP3): ~5 Mb, breakpoints at BP2 and BP3

Deleted genes in the typical deletion include UBE3A, GABRB3, GABRA5, GABRG3, ATP10A, and several others. The contiguous gene deletion explains the more severe phenotype in deletion patients compared to those with UBE3A-only mutations.

Epigenetic Information

The 15q11-q13 region is regulated by an imprinting control region (ICR) that controls parent-of-origin-specific gene expression:

The ICR is located at the SNRPN/SNURF promoter region
The maternal ICR is methylated → silences the paternal-specific gene cluster (SNRPN, NECDIN, MAGEL2, snoRNAs)
In neurons, UBE3A-ATS (antisense transcript) extends ~460 kb from the SNRPN locus and silences the paternal UBE3A allele in cis
Neuron-specific CTCF loops between MAGEL2-SNRPN and PWAR1-UBE3A regulate the locus during neuronal differentiation (PMID: 39045627)
R-loop formation at the Snord116 locus mediates topoisomerase inhibitor effects on UBE3A-ATS expression (PMID: 23918391)

Modifier Genes

GABRB3, GABRA5, GABRG3: Deleted in the common 15q11-q13 deletion; their loss contributes to more severe epilepsy and phenotype in deletion patients
Genetic background effects: Mouse studies demonstrate strain-dependent phenotype severity, suggesting modifier loci elsewhere in the genome (PMID: 28814801)

5. Environmental Information

AS is a purely genetic disorder. No environmental factors, lifestyle factors, or infectious agents are known to cause or significantly modify the disease. However, some environmental/management factors influence symptom expression:

Iron deficiency may contribute to sleep disruption in AS patients; iron therapy showed modest improvement in sleep difficulties (PMID: 32713229)
Medication effects: Antiepileptic drugs can suppress respiratory rates, highlighting complex interplay between treatment, genotype, and physiological function (PMID: 40200228)
Carbamazepine, oxcarbazepine, and vigabatrin should be avoided as they may induce nonconvulsive status epilepticus in AS patients (PMID: 32269945)

6. Mechanism / Pathophysiology

Molecular Pathways

Primary Pathway: Ubiquitin-Proteasome System (UPS) - UBE3A functions as an E3 ubiquitin ligase in the HECT domain family - Catalyzes attachment of ubiquitin to substrate proteins, targeting them for proteasomal degradation - Loss of UBE3A leads to accumulation of substrate proteins that impair neuronal function - GO terms: GO:0016567 (protein ubiquitination), GO:0006511 (ubiquitin-dependent protein catabolic process)

Downstream Pathways Affected: - Synaptic plasticity: Impaired long-term potentiation (LTP) and long-term depression (LTD) in hippocampus - GABAergic neurotransmission: Reduced inhibitory tone, particularly involving extrasynaptic GABA_A receptors - mTOR signaling: Dysregulated protein synthesis at synapses - CaMKII signaling: Altered calcium/calmodulin-dependent protein kinase II activity

Causal Chain: From UBE3A Loss to Clinical Manifestations

GENETIC DEFECT: Loss of maternal UBE3A
 |
MOLECULAR: Loss of E3 ubiquitin ligase activity
 |
CELLULAR: Accumulation of UBE3A substrates
    |                    |                    |
Synaptic dysfunction   Mitochondrial       Impaired protein
(AMPAR trafficking,    dysfunction          homeostasis
 LTP/LTD deficits)    (Complex III/IV ↓,   (proteasome
               ROS ↑)               overload)
    |                    |                    |
E/I imbalance         Oxidative stress     Disrupted neuronal
(GABAergic ↓)         in hippocampus       development
    |                    |                    |
CLINICAL PHENOTYPES:
  Epilepsy <---------- Cognitive deficits ---------> Motor dysfunction
  Sleep disorders      Speech absence               Ataxia
  EEG abnormalities    Learning disability           Tremor

Cellular Processes

Synaptic Dysfunction: - Loss of UBE3A results in development of "silent" synapses lacking functional AMPA receptors containing GluA1 (PMID: 28890050) - Excitation/inhibition (E/I) imbalance: decreased inhibitory transmission and increased excitatory transmission in mPFC layer 5 pyramidal neurons (PMID: 30082419) - Cell types: CL:0000540 (neuron), CL:0000617 (GABAergic neuron), CL:0000598 (pyramidal neuron)

GABAergic Dysfunction: The epilepsy phenotype involves tonic GABA-pathy: tonic activation of extrasynaptic GABA_A receptors causes characteristic high-amplitude slow wave activity (PMID: 30680721). The GABRB3 gene (encoding GABA_A receptor β3 subunit), which is deleted in ~70% of AS patients, contributes to this dysfunction. Mice with inactivated GABRB3 show absence-like seizures from abnormal thalamocortical hypersynchrony (PMID: 10684875).

Mitochondrial Dysfunction

A significant finding is that UBE3A loss leads to mitochondrial respiratory chain dysfunction:

Increased superoxide levels in hippocampal CA1: "AS mice have increased levels of superoxide in area CA1 of the hippocampus that is reduced by MitoQ, a mitochondria-specific antioxidant. In addition, we found that MitoQ rescued impairments in hippocampal synaptic plasticity and deficits in contextual fear memory exhibited by AS model mice" (PMID: 26658871)
Impaired respiratory chain complexes III and IV in hippocampus and cerebellum: "we report administration of idebenone, a potent CoQ10 analogue, to the Ube3a(m-/p+) mouse model corrects motor coordination and anxiety levels, and also improves the expression of complexes III and IV in hippocampus CA1 and CA2 neurons and cerebellum" (PMID: 25684537)
Bioinformatics analyses confirm Ube3a-dependent effects on mitochondrial-related pathways (PMID: 32532103)
GO terms: GO:0005739 (mitochondrion), GO:0006120 (mitochondrial electron transport)

White Matter and Myelination Deficits

AS individuals show significant brain volume reductions: by 6–12 years of age, white matter is reduced by 26% and gray matter by 21%. In AS mice, there is a global delay in the onset of myelination that is caused by loss of UBE3A in neurons rather than oligodendrocytes (PMID: 39726042).

Molecular Profiling

Transcriptomics: Ube3a-dependent transcriptome changes include mitochondrial pathway genes, synaptic genes, and neurodevelopmental regulators (PMID: 32532103).

Epigenomics: The 15q11-q13 locus undergoes dynamic methylation changes during neuronal differentiation, with neuron-specific CTCF loop formation and allele-specific DMRs (PMID: 39045627).

7. Anatomical Structures Affected

Organ Level

Structure	UBERON Term	Involvement
Brain (primary)	UBERON:0000955	Primary organ affected; intellectual disability, seizures, ataxia
Cerebellum	UBERON:0002037	Motor coordination deficits, ataxia
Hippocampus	UBERON:0002421	Learning/memory deficits, synaptic plasticity impairment
Cerebral cortex	UBERON:0000956	Seizures, cognitive dysfunction
Thalamus	UBERON:0001897	Thalamocortical hyperexcitability, EEG abnormalities
Medial prefrontal cortex	UBERON:0000451	E/I imbalance, behavioral phenotype
Skeletal system (secondary)	UBERON:0001434	Scoliosis
Gastrointestinal tract (secondary)	UBERON:0001555	Dysphagia, constipation, GERD

Cell Types Affected

Cell Type	CL Term	Role in Disease
Pyramidal neuron	CL:0000598	E/I imbalance, synaptic dysfunction
GABAergic interneuron	CL:0000617	Reduced inhibitory tone
Purkinje cell	CL:0000121	Cerebellar motor dysfunction
Thalamic reticular neuron	CL:0011005	Thalamocortical oscillation abnormalities
Oligodendrocyte	CL:0000128	Myelination delay (secondary to neuronal UBE3A loss)

Subcellular Level

Compartment	GO Term	Involvement
Synapse (postsynaptic)	GO:0045202	AMPAR trafficking, synaptic plasticity
Mitochondria	GO:0005739	Respiratory chain dysfunction, ROS
Proteasome	GO:0000502	Impaired protein degradation
Nucleus	GO:0005634	Transcriptional regulation, epigenetics

8. Temporal Development

Onset

Typical age of onset: 6–12 months (developmental delay becomes apparent)
Onset pattern: Insidious; initial presentation is delayed developmental milestones
Prenatal period: Generally normal pregnancy and birth
First signs: Feeding difficulties, hypotonia in infancy; developmental delay apparent by 6–12 months

Progression

Age Period	Key Features
0–6 months	Nonspecific: feeding difficulties, hypotonia, possible subtle developmental delay
6–24 months	Developmental delay becomes apparent; seizure onset (1–3 years most common)
2–6 years	Full phenotype emerges: severe ID, absent speech, ataxia, characteristic behavior, epilepsy
6–12 years	Seizures may improve; motor skills plateau; scoliosis may develop
Adolescence	Seizure frequency often decreases; behavioral issues may change; puberty normal timing
Adulthood	Stable intellectual disability; ongoing need for care; obesity risk increases; seizures may recur

Disease course: Chronic, lifelong
Progression rate: Developmental progress is very slow but present; the condition is not degenerative
Critical periods: Early childhood (before age 5) represents a window where therapeutic intervention may have the greatest impact on neurodevelopmental outcomes

9. Inheritance and Population

Epidemiology

Measure	Value
Prevalence	~1 in 12,000–20,000 live births (approximately 5–8 per 100,000)
Incidence	~1 in 15,000 newborns

Inheritance Pattern

Mode: Complex — not simple Mendelian
For deletions and UPD cases: typically de novo (sporadic), recurrence risk <1%
For UBE3A point mutations: may be inherited from a carrier mother (who inherited it from her father and is unaffected); recurrence risk up to 50% if mother carries the mutation
For imprinting defects: most sporadic (recurrence <1%), but rare familial forms exist with up to 50% recurrence risk
Penetrance: Complete when maternal UBE3A is non-functional
Expressivity: Variable; influenced by genotype class and genetic background

Germline Mosaicism

Germline mosaicism has been reported for UBE3A mutations and deletions, which can lead to unexpected recurrence in families with apparently de novo mutations. This is an important consideration in genetic counseling.

Population Demographics

Sex ratio: Approximately 1:1 (males and females equally affected)
Geographic distribution: Worldwide; no ethnic predilection identified
Affected populations: All ethnic groups affected equally; prevalence estimates are similar across studied populations

10. Diagnostics

Recommended Diagnostic Algorithm

Clinical suspicion based on developmental delay, absent speech, characteristic behavior, movement disorder
DNA methylation analysis of the SNRPN locus (first-line test; detects ~80% of AS: deletions, UPD, and imprinting defects)
If methylation normal → UBE3A gene sequencing (detects ~11–15% intragenic mutations)
If deletion detected → FISH or chromosomal microarray to define deletion extent
If methylation abnormal but no deletion → microsatellite analysis to distinguish UPD from imprinting defect

"The most sensitive single approach to diagnosing both PWS and AS is to study methylation patterns within 15q11-q13" (PMID: 20459762).

Clinical Tests

EEG (Electroencephalography): - Highly sensitive diagnostic biomarker - Characteristic patterns identified in 88% of cases (Dan and Boyd classification) (PMID: 39404036) - Abnormal baseline brain activity in all AS patients - Useful for early diagnosis before genetic confirmation

MRI (Brain Imaging): - May show cortical atrophy, delayed myelination, reduced white matter volume - White matter reduction already apparent by 1 year of age (PMID: 39726042) - Not specific; often normal in early life

Sleep Studies (Polysomnography): - Documents sleep architecture disruption - Lower respiratory rate during sleep (Cohen's d = 0.77 vs. controls) (PMID: 40200228) - Lower oxygen saturation (Cohen's d = 1.60) (PMID: 40200228)

Genetic Testing

Test	Utility	What It Detects
DNA methylation (MS-PCR, MS-MLPA)	First-line	Deletions, UPD, imprinting defects (~80% of AS)
Chromosomal microarray (CMA)	Characterize deletion	Deletion size, breakpoints
FISH	Confirm deletion	15q11-q13 deletion
UBE3A sequencing	Second-line	Point mutations (~11–15%)
Microsatellite analysis	Distinguish UPD from ID	Paternal UPD
Karyotype	Rare cases	Chromosomal translocations involving 15q
Whole exome sequencing (WES)	For AS-like cases	Alternative genetic diagnoses (SYNGAP1, SMARCE1, etc.)

Differential Diagnosis

Conditions that can mimic AS ("Angelman-like" phenotypes): - Pitt-Hopkins syndrome (TCF4 mutations) - Mowat-Wilson syndrome (ZEB2 mutations) - Rett syndrome (MECP2 mutations) - Coffin-Siris syndrome (SMARCE1, other SWI/SNF mutations) (PMID: 30548424) - SYNGAP1-related ID - Other genes: VAMP2, TBL1XR1, ASXL3, SATB2, SPTAN1, KCNQ3, SLC6A1, LAS1L (PMID: 34653234)

Screening

AS is not currently included in standard newborn screening panels
Methylation-based newborn screening is technically feasible; high-throughput methylation-specific quantitative melt analysis has shown 100% sensitivity and specificity (PMID: 40801290)
Carrier screening for UBE3A mutations can be offered to families with a known mutation

11. Outcome/Prognosis

Survival and Mortality

Life expectancy: Near-normal life expectancy in most cases
Childhood survival: European population study showed no deaths among AS children (n=46) by 10 years of age (PMID: 40484454)
Mortality risk: Primarily from seizure-related complications (SUDEP), aspiration, and respiratory complications

Morbidity and Function

Severe, lifelong intellectual disability requiring constant care
Most individuals never achieve independent living
Communication primarily through nonverbal means (gestures, augmentative devices)
Ambulatory function: most patients achieve walking, though with ataxic gait
Hospitalization rates: 59% of AS children required hospitalization in first year of life; 68% at ages 5–9 years (PMID: 40484454)

Disease Course and Complications

Epilepsy: Often improves in late childhood/early adulthood; 36 of 40 patients achieved drug remission in one cohort, though 24 of 36 later relapsed (PMID: 35904299)
Scoliosis: Progressive; may require surgical intervention
Obesity: Increasing prevalence with age
Respiratory complications: Aspiration risk, bradypnea during sleep
Surgical complications: Tonsillectomy complications in 75% of AS patients, including opioid toxicity and aspiration (PMID: 40776598)

Prognostic Factors

Genotype class is the strongest prognostic factor (deletions = worst prognosis)
Persistent epileptic seizures negatively influence severity (PMID: 35904299)
Early diagnosis and intervention may improve developmental outcomes

12. Treatment

Current Pharmacotherapy

Antiseizure Medications (MAXO:0000950 — pharmacotherapy):

Drug	Class	Evidence Level	Notes
Valproic acid (valproate)	Broad-spectrum ASM	First-line	Most commonly used; effective monotherapy
Levetiracetam	SV2A modulator	First-line	Commonly used; "Sodium valproate, levetiracetam, and benzodiazepines are the most commonly used anti-seizure medications" (PMID: 35917229)
Clobazam	Benzodiazepine	First-line
Ethosuximide	T-type Ca2+ channel blocker	Second-line	Effective for atypical absences
Clonazepam	Benzodiazepine	Adjunctive
Lamotrigine	Na+ channel blocker	Use with caution	May worsen myoclonus in some patients
Topiramate	Multiple mechanisms	Adjunctive
Cannabidiol (CBD)	CB receptor modulator	Emerging	Favorable retention and efficacy in intractable epilepsy (PMID: 41630268)

Medications to AVOID: Carbamazepine, oxcarbazepine, and vigabatrin may induce nonconvulsive status epilepticus (PMID: 32269945).

Sleep Management: - Melatonin replacement therapy (MAXO:0001298 — melatonin therapy): "emerging evidence suggests melatonin replacement therapy can improve sleep in many AS patients" (PMID: 32976638) - Iron supplementation for those with iron deficiency and sleep disturbance (PMID: 32713229)

Supportive and Rehabilitative Care (MAXO:0000011 — rehabilitation)

Physical therapy (MAXO:0000530): For motor skills, balance, gait training
Occupational therapy (MAXO:0000536): For fine motor skills, daily living activities
Speech/language therapy (MAXO:0000930): Augmentative and alternative communication (AAC)
Behavioral therapy: For autistic traits, hyperactivity, and sensory processing issues
Nutritional support: For dysphagia management; feeding therapy

Advanced/Experimental Therapeutics

Antisense Oligonucleotide (ASO) Therapy — Paternal UBE3A Reactivation:

This is the most promising therapeutic approach. ASOs targeting UBE3A-ATS aim to reduce the antisense transcript and unsilence the paternal UBE3A allele in neurons:

"ASO treatment achieved specific reduction of Ube3a-ATS and sustained unsilencing of paternal Ube3a in neurons in vitro and in vivo. Partial restoration of UBE3A protein in an Angelman syndrome mouse model ameliorated some cognitive deficits associated with the disease" (PMID: 25470045)
Prenatal ASO delivery achieved remarkable results: "in utero injection of the ASO in a mouse model of AS also resulted in successful restoration of UBE3A and phenotypic improvements in treated mice on the accelerating rotarod and fear conditioning. Strikingly, even intra-amniotic (IA) injection resulted in systemic biodistribution and high levels of UBE3A reactivation throughout the brain" (PMID: 38327047)
Multiple clinical trials are underway (e.g., Ionis/Roche GTI-801, GeneTx/Ultragenyx GTX-102)

Topoisomerase Inhibitors: - Topotecan and other topoisomerase inhibitors can unsilence paternal UBE3A by stabilizing R-loops at the Snord116 locus (PMID: 22190039, PMID: 23918391) - Effects can be enduring: paternal UBE3A expression remained elevated for at least 12 weeks after cessation of topotecan treatment (PMID: 22190039) - Clinical translation limited by toxicity concerns

Other Experimental Approaches: - Gene therapy: AAV-mediated UBE3A gene replacement - CRISPR-based approaches: Targeting UBE3A-ATS or imprinting marks - Ganaxolone (synthetic neurosteroid): Targeting extrasynaptic GABA_A receptors to restore inhibitory tone (PMID: 27986596) - TrkB agonists: Targeting BDNF/TrkB pathway for synaptic function (PMID: 32817301) - Mitochondria-targeted antioxidants: MitoQ and idebenone showed preclinical efficacy (PMID: 26658871, PMID: 25684537)

Surgical Interventions

Scoliosis surgery for progressive cases (MAXO:0000004 — surgical procedure)
Tonsillectomy for sleep-disordered breathing or sialorrhea; requires careful postoperative management due to high complication rate (75%) (PMID: 40776598)
Vagus nerve stimulation (VNS) for refractory epilepsy

13. Prevention

Primary Prevention

No primary prevention exists for de novo cases (the vast majority)
Genetic counseling (MAXO:0000079) is essential for families with known mutations to assess recurrence risk

Secondary Prevention (Early Detection)

Methylation-based diagnostic testing can confirm clinical suspicion as early as infancy
EEG may support early clinical suspicion before genetic confirmation
High-throughput methylation screening is technically feasible for population-level screening (PMID: 40801290)

Tertiary Prevention (Complication Management)

Early seizure control to minimize neurodevelopmental impact
Scoliosis monitoring and intervention
Respiratory monitoring during sleep
Nutritional management to prevent obesity and address dysphagia
Careful perioperative management (especially for opioid sensitivity)

Genetic Counseling

Recurrence risk estimation depends on molecular class
Deletion (de novo): <1% recurrence risk
UBE3A mutation (inherited from carrier mother): Up to 50% recurrence risk
Imprinting defect (sporadic): <1% recurrence risk
Prenatal testing available via chorionic villus sampling (CVS) or amniocentesis with methylation analysis
Preimplantation genetic diagnosis (PGD) available for families with known mutations

14. Other Species / Natural Disease

Naturally Occurring Disease

No naturally occurring Angelman syndrome has been documented in non-human species. However, UBE3A imprinting is conserved in mammals, and the 15q11-q13 syntenic region is conserved across several species.

Orthologous Genes

Species	Gene	NCBI Gene ID	Conservation
Mouse (Mus musculus)	Ube3a	22215	High; neuron-specific imprinting conserved
Rat (Rattus norvegicus)	Ube3a	361585	High
Dog (Canis lupus familiaris)	UBE3A	480906	Moderate
Zebrafish (Danio rerio)	ube3a	571085	Moderate
Fruit fly (Drosophila melanogaster)	dube3a	36434	Partial

15. Model Organisms

Mouse Models

The Ube3a maternal-null mouse (Ube3a^m-/p+) is the primary model, recapitulating key AS features:

"Animal models of AS recapitulate the genotypic and phenotypic features observed in AS patients, and have been invaluable for understanding the disease process as well as identifying appropriate drug targets" (PMID: 32088294).

Phenotypes recapitulated: - Increased seizure susceptibility and epileptiform spiking - Increased delta power on EEG: "Ube3a-del mice exhibited reduced seizure threshold compared to WT. EEG illustrated that Ube3a-del mice had increased epileptiform spiking activity and delta power" (PMID: 33549123) - Motor deficits (rotarod, wire hang, open field) - Learning and memory deficits (fear conditioning, Morris water maze) - Sleep disruptions - Enhanced nociception (PMID: 28931574) - Altered ultrasonic vocalizations (PMID: 20808828)

Strain-Dependent Effects: - C57BL/6J: Most robust behavioral impairments, spontaneous EEG polyspikes, increased spectral power - 129: Poor wire hang and contextual fear conditioning, lower seizure threshold, altered spectral power - F1 hybrid (C57BL/6J x 129): Milder impairments, infrequent polyspikes (PMID: 28814801)

Large Deletion Model (Ube3a-Gabrb3): Mice with a 1.6-Mb maternal deletion from Ube3a to Gabrb3 show more severe phenotypes with spontaneous seizures, abnormal EEG, and increased ultrasonic vocalizations, better recapitulating the contiguous gene deletion form of AS in humans (PMID: 20808828).

Model Limitations

Mice do not fully recapitulate the speech impairment (USV changes serve as proxy)
Characteristic "happy" behavioral phenotype is difficult to assess in mice
Myelination delay normalizes within days in mice vs. potentially months/years in humans (PMID: 39726042)
Melatonin findings differ: some mouse strains lack melatonin production entirely, yet still show sleep problems (PMID: 32976638)

Other Models

iPSC-derived neurons: Patient-derived iPSCs provide human cell models for studying UBE3A-dependent mechanisms and drug screening (PMID: 33370574)
LUHMES neuronal cell line: Validated for studying UBE3A-ATS expression dynamics and imprinting (PMID: 39045627)
Drosophila dUbe3a models: Used for studying ubiquitin pathway biology

Model Resources

MGI: Mouse Genome Informatics database
IMPC: International Mouse Phenotyping Consortium
IMSR: International Mouse Strain Resource

Key Findings (Expanded)

Finding 1: UBE3A Imprinting as the Central Disease Mechanism

Angelman Syndrome is fundamentally a disorder of genomic imprinting. The UBE3A gene at 15q11-q13 shows tissue-specific imprinting: it is biallelically expressed in most tissues but monoallelically (maternal-only) expressed in neurons. The paternal allele is silenced in neurons by UBE3A-ATS, a large (~460 kb) non-coding antisense transcript originating from the SNRPN/SNURF promoter region. Five distinct genetic mechanisms can disrupt maternal UBE3A function, with maternal deletions of 15q11-q13 being the most common (~70%). This understanding has been transformative for therapeutic development, as the intact paternal allele represents a therapeutic target for gene reactivation strategies.

Finding 2: Genotype-Phenotype Severity Gradient

Systematic analysis of large AS patient cohorts (n=250 patients, 848 assessments) has established a clear genotype-phenotype correlation. Deletion patients are the most severely affected across all clinical domains, followed by UPD patients, with imprinting defect and UBE3A mutation patients showing the mildest phenotypes. Within UBE3A mutation carriers, truncating mutations produce more severe impairment than missense mutations. The more severe phenotype in deletion patients is attributed to the contiguous gene syndrome effect — loss of neighboring genes (GABRB3, GABRA5, GABRG3) compounds the neurological impact of UBE3A loss alone.

Finding 3: Epilepsy as the Primary Clinical Challenge

Epilepsy is the most medically significant comorbidity in AS, affecting 80–90% of patients. Seizures typically onset between ages 1–3 years and are often pharmacoresistant, requiring polytherapy. The epilepsy mechanism involves GABAergic dysfunction and thalamocortical hyperexcitability, with deletion patients showing significantly higher epilepsy prevalence (88%) compared to non-deletion patients (61.9%). Characteristic EEG patterns serve as an important early diagnostic biomarker, with abnormal baseline activity detected in all patients.

Finding 4: Mitochondrial Dysfunction as a Druggable Pathophysiological Pathway

Beyond synaptic dysfunction, UBE3A loss leads to mitochondrial respiratory chain impairment, with elevated superoxide levels in hippocampal CA1 and reduced activity of complexes III and IV. This pathway represents a potentially druggable target: mitochondria-specific antioxidants (MitoQ) rescued synaptic plasticity and memory deficits, while idebenone (CoQ10 analogue) corrected motor coordination and improved respiratory chain complex expression. These findings suggest that antioxidant therapy could serve as an adjunctive treatment strategy.

Finding 5: ASO Therapy as a Transformative Therapeutic Strategy

The most revolutionary therapeutic approach targets the intact but silenced paternal UBE3A allele. ASOs targeting UBE3A-ATS achieve specific reduction of the antisense transcript and sustained unsilencing of paternal UBE3A in neurons. Preclinical studies demonstrate partial UBE3A protein restoration and amelioration of cognitive deficits. Remarkably, prenatal ASO delivery achieved broad brain biodistribution and significant phenotypic improvements, suggesting that early intervention may be critical for maximum therapeutic benefit. Multiple clinical trials are advancing this approach toward human application.

Finding 6: Mouse Models as Essential Preclinical Tools

Ube3a maternal-null mice faithfully recapitulate the core features of AS including seizure susceptibility, EEG abnormalities, motor deficits, learning impairments, and sleep disruptions. The large deletion model (Ube3a-Gabrb3) more closely mimics the contiguous gene deletion form seen in most patients. Strain-dependent effects highlight the importance of genetic background, with C57BL/6J showing the most robust phenotypes. These models have been instrumental for therapeutic development and mechanistic understanding.

Evidence Base

PMID	Key Contribution
39293689	UBE3A gene dynamics in brain, neuron-specific imprinting
32088294	Comprehensive review of AS mouse models and therapy
25470045	First ASO-mediated paternal UBE3A reactivation
38327047	Prenatal ASO delivery with brain-wide UBE3A restoration
32792659	Genotype-phenotype severity correlations (n=250)
41525882	Italian registry genotype-phenotype data (n=213)
32893075	Epilepsy prevalence, mechanisms, and treatment review
35917229	Seizure types and neurological treatment approach
26658871	Mitochondrial superoxide in AS hippocampus; MitoQ rescue
25684537	Idebenone rescue of mitochondrial complex III/IV deficits
33549123	EEG and seizure phenotyping in AS mouse model
22190039	Topoisomerase inhibitors unsilence paternal Ube3a
23918391	R-loop formation mediates topotecan action at Snord116
39726042	White matter deficits and myelination delay in AS
40200228	Respiratory rate abnormalities during sleep
40484454	European population-based health outcomes
20459762	Practice guidelines for molecular diagnosis
11748306	Distinct phenotypes by molecular class (n=104)
28814801	Strain-dependent AS phenotypes in mouse models
20808828	Large deletion mouse model (Ube3a-Gabrb3)
30082419	E/I imbalance in mPFC of AS mice
28890050	Rnf2/Ube3a interaction in synapse maturation
39045627	CTCF loops and methylome in 15q11-q13 imprinting
32976638	Melatonin and sleep regulation in AS
30680721	GABA-pathy mechanisms in AS epilepsy
10684875	GABRB3 and thalamocortical oscillations
32532103	Ube3a-dependent mitochondrial transcriptome changes
40116126	Autistic traits trajectories in AS children
40852931	Dysphagia prevalence in Chinese AS cohort
41153459	ART and imprinting disorder risk
40801290	High-throughput methylation screening feasibility
34653234	Genes in Angelman-like syndrome differential diagnosis

Limitations and Knowledge Gaps

Unknown mechanism cases (~10–15%): A significant fraction of clinically diagnosed AS patients lack an identifiable molecular defect, limiting genetic counseling and therapeutic targeting.
Limited natural history data: Long-term longitudinal studies of AS patients through adulthood and aging are sparse; most data derive from pediatric cohorts.
Translation gap for ASO therapy: While preclinical results are highly promising, several clinical trials of ASO-based therapies have encountered safety challenges (e.g., transient lower limb weakness), and optimal dosing, timing, and delivery remain to be established.
Mitochondrial dysfunction mechanism unclear: While mitochondrial dysfunction is documented in AS models, the precise molecular link between UBE3A loss and mitochondrial respiratory chain impairment remains to be elucidated. Specific UBE3A substrates in the mitochondrial pathway have not been identified.
Biomarker development: Validated clinical biomarkers for tracking disease progression and treatment response are still needed. EEG power spectral analysis and white matter volume are promising but not yet standardized.
Gene-environment interactions: The role of environmental modifiers in AS severity is poorly studied.
Quality of life measures: AS-specific quality of life instruments are lacking; existing tools (EQ-5D, SF-36) are not validated for AS populations.
Adult AS: Data on health outcomes, complications, and optimal management strategies for adults with AS are limited.
Cell-type specificity: While recent studies have begun investigating cell-type-specific contributions of UBE3A loss, a comprehensive single-cell atlas of AS brain pathology is lacking.
Therapeutic timing: The critical developmental window for therapeutic intervention remains poorly defined in humans; mouse data suggest earlier treatment is better, but the translational timing remains uncertain.

Proposed Follow-up Experiments/Actions

Clinical biomarker validation: Conduct multicenter studies to validate EEG delta power, white matter volume (MRI), and sleep respiratory parameters as quantitative biomarkers for AS clinical trials.
Mitochondrial pathway dissection: Perform targeted proteomics to identify UBE3A substrates in the mitochondrial pathway; conduct in vivo metabolomics in AS mouse models with and without mitochondria-targeted interventions.
ASO therapy optimization: Investigate optimal timing windows for ASO delivery (prenatal vs. postnatal vs. early childhood) using stage-specific conditional Ube3a reactivation models.
Unknown mechanism characterization: Apply whole genome sequencing and epigenomic profiling (methylation arrays, ATAC-seq) to the ~10–15% of clinically diagnosed AS patients without identified molecular defects.
Longitudinal natural history study: Establish a prospective, multi-decade cohort study tracking AS patients from infancy through adulthood with standardized clinical assessments, biomarker collection, and quality-of-life measures.
Combination therapy evaluation: Test whether combining ASO-mediated UBE3A reactivation with mitochondria-targeted antioxidants (MitoQ/idebenone) produces synergistic phenotypic rescue in AS mouse models.
Cell-type-specific UBE3A function: Use single-cell RNA-seq and spatial transcriptomics in AS and control brains to identify the neuronal subtypes most affected by UBE3A loss and prioritize therapeutic targets.
Population-based screening pilot: Design a pilot study for methylation-based newborn screening for AS to assess feasibility, yield, and clinical utility of early detection.
Adult AS health outcomes: Conduct comprehensive health assessments in adult AS populations to define age-related complications and optimize lifelong management strategies.
Gene therapy clinical development: Advance AAV-based UBE3A gene replacement therapy through preclinical safety and efficacy studies toward clinical trial readiness, with particular attention to dosing and immune response.

Report generated: 2026-05-05 Based on analysis of 63 primary literature sources 6 confirmed findings across genetics, phenotype, pathophysiology, and therapeutics

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Angelman Syndrome (MONDO:0007113) — Disease Characteristics Research Report

Executive summary

1. Disease information

1.1 Definition and overview

1.2 Key identifiers

1.3 Synonyms / alternative names

1.4 Evidence provenance (individual vs aggregated)

2. Etiology

2.1 Primary causal factors

2.2 Genetic risk factors (causal variants / molecular subtypes)

2.3 Environmental risk factors and protective factors

2.4 Gene–environment interactions

3. Phenotypes

3.1 Core phenotype domains (with suggested HPO terms)

3.2 EEG phenotypes and quantitative biomarkers (key statistics)

3.3 Quality of life (QoL) impact

4. Genetic / molecular information

4.1 Causal genes

4.2 Pathogenic variant classes and structural mechanisms

4.3 Functional consequence

4.4 Epigenetic information (imprinting)

4.5 Modifier genes / locus context

5. Environmental information

6. Mechanism / pathophysiology

6.1 Causal chain (from genotype to phenotype)

6.2 Molecular pathways and cellular processes (selected, model-supported)

7. Anatomical structures affected

7.1 Organ/system level

7.2 Tissue and cellular level

7.3 Subcellular

8. Temporal development

8.1 Onset

8.2 Progression/course

8.3 Critical windows for intervention

9. Inheritance and population

9.1 Epidemiology

9.2 Inheritance pattern

9.3 Sex ratio, geography, variant geography

10. Diagnostics

10.1 Molecular diagnostic workflow (real-world implementation)

10.2 EEG as supportive diagnostic/biomarker tool

10.3 Differential diagnosis

11. Outcomes / prognosis

11.1 Mortality and survival

11.2 Morbidity

12. Treatment

12.1 Current clinical management (standard of care)

12.2 Disease-modifying and advanced therapeutics (2023–2024 emphasis)

A) ASO-mediated paternal UBE3A unsilencing (targeting UBE3A-ATS)

B) Small-molecule unsilencing of paternal UBE3A (2024)

C) RNA-targeting CRISPR/Cas (Cas13) unsilencing (2023)

D) Outcome measures / biomarkers for trials and real-world use

12.3 Clinical trials (real-world implementation; key records)

12.4 Suggested MAXO terms (examples)

13. Prevention

14. Other species / natural disease

15. Model organisms

15.1 Mouse models

15.2 Rat models

15.3 Nonhuman primate (rhesus macaque)

15.4 Human stem cell models (iPSC/ESC and organoids)