Angelman Syndrome

1. Clinical Overview

Summary

Angelman syndrome (AS) is a rare neurogenetic disorder caused by loss of function of the maternally inherited UBE3A gene on chromosome 15q11.2-q13.1. First described by British paediatrician Harry Angelman in 1965, the syndrome is characterised by a distinctive constellation of features including severe intellectual disability, absent or severely limited speech, movement disorders (ataxia, tremor, jerky limb movements), characteristic behaviours (frequent laughter, happy demeanour, hand-flapping, fascination with water), and seizures that are often treatment-resistant. [1,2]

The condition results from a unique phenomenon called genomic imprinting, whereby certain genes are expressed exclusively from one parental allele. In neurons, UBE3A is expressed almost exclusively from the maternal chromosome, while the paternal allele is epigenetically silenced. Consequently, loss of the maternal UBE3A copy leaves neurons without functional UBE3A protein, resulting in the characteristic neurological phenotype. This same chromosomal region (15q11.2-q13.1), when affected on the paternal chromosome, causes the clinically distinct Prader-Willi syndrome. [3,4]

The estimated prevalence is 1 in 12,000 to 1 in 20,000 live births, with equal distribution between sexes and across all ethnic groups. Diagnosis is confirmed through genetic testing, typically using DNA methylation analysis as the first-line test. Management is supportive and multidisciplinary, focusing on seizure control, communication strategies (augmentative and alternative communication), developmental intervention, sleep management, and comprehensive family support. While affected individuals require lifelong care, those with appropriate support can live into adulthood with near-normal life expectancy and meaningful quality of life. [5,6]

Key Facts

Key Mnemonic

"A for Angelman, A for mAternAl": Angelman syndrome results from loss of the MATERNAL copy of the UBE3A gene. Contrast with Prader-Willi syndrome (Paternal loss) — same region, opposite parent.

Clinical Pearls

"Happy Puppet" Terminology — Deprecated: The historic term "Happy Puppet Syndrome" is considered offensive and stigmatising. Use "Angelman syndrome" exclusively.

Seizure Medication Warning: Carbamazepine, oxcarbazepine, vigabatrin, and tiagabine can worsen seizures in Angelman syndrome. Valproate, levetiracetam, and clobazam are typically first-line agents. [7]

EEG Pattern — Diagnostic Clue: Characteristic high-amplitude slow (2-3 Hz) delta activity with intermittent rhythmic theta over posterior regions is highly suggestive of AS, even before clinical seizures manifest. [8]

Deletion Size Matters: Larger deletions (Class I: BP1-BP3) may have more severe phenotypes than smaller deletions (Class II: BP2-BP3), though significant phenotypic variability exists. [9]

UPD and Imprinting Defects — Milder Phenotype: Patients with paternal uniparental disomy (UPD) or imprinting centre defects often have milder presentations with better expressive language and fewer seizures compared to deletion patients. [10]

Why This Matters Clinically

Angelman syndrome requires early recognition for appropriate developmental support, seizure management, and genetic counselling. The distinctive behavioural phenotype (happy demeanour, frequent laughter) combined with developmental delay can sometimes paradoxically delay diagnosis in early infancy when these "positive" behaviours mask underlying neurological impairment. Accurate genetic diagnosis is essential for determining recurrence risk, which varies dramatically by molecular mechanism (from less than 1% for de novo deletion to 50% for inherited UBE3A mutations). With appropriate support, individuals with AS can lead fulfilling lives, though the need for lifelong care places significant demands on families requiring comprehensive support services.

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2. Epidemiology

Incidence & Prevalence

Demographics

Age Distribution

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3. Aetiology & Pathophysiology

Genetic Mechanisms

Angelman syndrome results from loss of function of the maternally expressed UBE3A gene at chromosome 15q11.2-q13.1. The UBE3A gene encodes E6-AP ubiquitin ligase (also known as UBE3A or E6AP), an E3 ubiquitin-protein ligase crucial for protein degradation through the ubiquitin-proteasome pathway. [1,3]

Molecular Mechanisms of Disease

Deletion Classes

Large deletions are classified by breakpoint (BP) location:

Genomic Imprinting at 15q11.2-q13.1

The 15q11.2-q13.1 region contains multiple imprinted genes expressed from only one parental allele:

Paternally Expressed (Maternally Silenced):

• SNRPN (small nuclear ribonucleoprotein polypeptide N)
• SNURF
• Multiple snoRNA genes (HBII-52 cluster, HBII-85 cluster)
• NDN (necdin)
• MAGEL2
• MKRN3
• These genes are lost in Prader-Willi syndrome

Maternally Expressed (Paternally Silenced in Neurons):

• UBE3A — expressed from maternal allele in neurons only
• ATP10A (tissue-specific)

The tissue-specific imprinting of UBE3A is particularly important: UBE3A is biallelically expressed in most tissues, but in neurons, the paternal allele is silenced by a long non-coding antisense transcript (UBE3A-ATS) originating from the SNURF-SNRPN locus. This neuron-specific paternal silencing explains why loss of the maternal UBE3A allele causes neurological disease while other tissues remain largely unaffected. [3,4,12]

Pathophysiology

Step 1: Loss of Maternal UBE3A Function

Through any of the mechanisms described above, the maternally-derived functional UBE3A allele is lost. Since the paternal allele is silenced in neurons by UBE3A-ATS, neurons are left without functional UBE3A protein.

Step 2: Impaired Ubiquitin-Proteasome Function

UBE3A (E6-AP) is an E3 ubiquitin ligase that:

• Transfers ubiquitin to target proteins
• Marks proteins for degradation by the 26S proteasome
• Regulates levels of multiple neuronal proteins

Key UBE3A substrates include:

• Arc (activity-regulated cytoskeleton-associated protein) — regulates AMPA receptor trafficking and synaptic plasticity [13]
• Sacsin — involved in mitochondrial dynamics
• Annexin A1 — role in inflammation and neuronal signalling
• p53 — tumour suppressor (in presence of HPV E6 protein)

Step 3: Synaptic Dysfunction

Loss of UBE3A leads to:

• Impaired synaptic plasticity — abnormal long-term potentiation (LTP)
• Altered dendritic spine morphology — immature spine phenotype
• Disrupted excitatory/inhibitory balance — cortical hyperexcitability
• Abnormal neuronal development — altered migration and differentiation
• Mitochondrial dysfunction — impaired energy metabolism [14]

Step 4: Clinical Phenotype

The neuronal dysfunction manifests as:

• Severe intellectual disability — learning and memory deficits
• Absent/minimal speech — expressive language severely affected
• Movement disorder — ataxia, tremor from cerebellar/motor pathway dysfunction
• Seizures — cortical hyperexcitability
• Sleep disturbance — disrupted circadian rhythm, reduced melatonin
• Characteristic behaviours — limbic system involvement

Genotype-Phenotype Correlations

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4. Clinical Presentation

Natural History by Age

Prenatal Period

• Usually normal prenatal course
• No consistent ultrasound findings
• Normal birth weight and APGAR scores typical

Infancy (0-12 months)

Early Childhood (1-4 years)

Later Childhood (5-12 years)

Adolescence and Adulthood

Cardinal Clinical Features

Consistent Features (100% of Patients)

1. Severe Developmental Delay

   • IQ typically 20-40
   • Functional level remains below 24-30 months
   • Learning continues throughout life, albeit slowly

2. Movement Disorder

   • Ataxic, wide-based, stiff-legged gait
   • Jerky, puppet-like movements of limbs
   • Tremulous movement of extremities (action tremor)
   • Arms often held up and flexed, especially when walking or excited
   • Hypermotoric, hyperkinetic behaviour

3. Speech Impairment

   • Absent or minimal expressive language (typically less than 6 words)
   • Receptive language better than expressive
   • Non-verbal communication often well developed (gestures, eye pointing)
   • May use augmentative communication devices successfully

4. Behavioural Phenotype

   • Happy, excitable demeanour
   • Frequent smiling and laughter (often unprovoked)
   • Hand-flapping when excited
   • Easily entertained; love of social interaction
   • Short attention span
   • Mouthing behaviours
   • Attraction to/fascination with water, shiny objects, mirrors

Frequent Features (> 80% of Patients)

1. Microcephaly

   • Typically acquired (normal at birth)
   • Deceleration of head growth by age 2 years
   • Absolute or relative microcephaly by age 2

2. Seizures

   • Onset typically between 1-3 years (can be later)
   • Multiple seizure types common (see Seizure Section)
   • Often difficult to control
   • May improve in adolescence/adulthood

3. Abnormal EEG

   • Characteristic pattern even without clinical seizures
   • High-amplitude slow spike-wave activity (2-3 Hz)
   • Rhythmic 4-6 Hz theta activity (often frontal)
   • Runs of high-amplitude 2-3 Hz activity posteriorly
   • Triphasic waves [8]

Associated Features (20-80% of Patients)

Facial Features

The facial gestalt in Angelman syndrome becomes more apparent with age:

Additional craniofacial features:

• Flat occiput
• Midface hypoplasia (mild)
• Wide nasal base
• Upslanting palpebral fissures (variable)
• Brachycephaly

Seizure Characteristics

Seizures occur in 80-90% of individuals with AS and are a major cause of morbidity. [7,15]

Seizure Types

EEG Characteristics

The EEG in Angelman syndrome shows characteristic abnormalities that can support diagnosis even before clinical seizures: [8]

Red Flags

[!CAUTION] Red Flags — Urgent Attention Required:

• Status epilepticus — Common in AS; requires emergency management
• Prolonged seizures (> 5 minutes) — Low threshold for rescue medication
• Non-convulsive status — Consider if prolonged confusion/regression
• Aspiration/choking — Swallowing difficulties, especially liquids
• Severe self-injury — May occur during behavioural dysregulation
• Extreme sleep disturbance — Impacts child and family health
• Hyperthermia — Impaired thermoregulation; risk in hot weather
• Constipation with distension — Risk of impaction
• New onset regression — Consider other causes (seizures, metabolic)

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5. Differential Diagnosis

Primary Differentials

Comparison: Angelman Syndrome vs Prader-Willi Syndrome

When to Suspect Alternative Diagnosis

Consider alternative diagnosis if:

• Developmental regression (more typical of Rett, mitochondrial disorders)
• Early severe hypotonia with failure to thrive (PWS, myopathy)
• Normal EEG pattern in older child with suspected AS
• Male with X-linked inheritance pattern (Christianson syndrome)
• Hirschsprung disease present (Mowat-Wilson)
• Hyperventilation episodes (Pitt-Hopkins)
• Negative methylation testing and negative UBE3A sequencing

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6. Clinical Examination

General Approach

A systematic examination focusing on key features of Angelman syndrome:

General Inspection

• Behaviour: Happy, smiling, excitable demeanour
• Interaction: Seeks social engagement; may approach examiner
• Movement: Hyperkinetic; hand-flapping; tremulous
• Posture: Arms may be held flexed and elevated
• Build: Usually normal; may trend toward obesity in adults

Growth Parameters

Dysmorphic Examination

Neurological Examination

Communication Assessment

Specific Tests

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7. Investigations

Diagnostic Testing Algorithm

Step 1: Clinical Suspicion ↓ Step 2: DNA Methylation Analysis (First-line)

• Abnormal → AS confirmed; proceed to characterise mechanism
• Normal → If strong suspicion, proceed to Step 5 ↓ Step 3: Determine Molecular Mechanism
• Chromosomal Microarray (CMA) or FISH → Detects deletion
• If no deletion → UPD testing (SNP array, microsatellite analysis)
• If no deletion or UPD → Imprinting centre analysis ↓ Step 4: Family Testing
• If deletion → Parental karyotype (rule out balanced translocation)
• If UBE3A mutation → Maternal testing for carrier status
• If imprinting defect → Characterise (deletion vs epimutation) ↓ Step 5: If Methylation Normal but Clinical Suspicion High
• UBE3A gene sequencing
• Consider alternate diagnoses if negative

Specific Investigations

Genetic Testing

Neurological Investigations

Other Investigations

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8. Classification

Molecular Classification

Deletion Size Classification

Severity Classification (Functional)

No validated severity classification exists, but functional domains can be assessed:

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9. Management

Management Principles

1. Multidisciplinary team approach — essential for comprehensive care
2. Early intervention — optimise developmental potential
3. Seizure control — major impact on quality of life
4. Communication support — AAC enables meaningful participation
5. Family-centred care — support for whole family
6. Transition planning — prepare for adult services

Multidisciplinary Team

Seizure Management

Pharmacological Management

Medications to AVOID

[!WARNING] Contraindicated or Use with Extreme Caution:

• Carbamazepine — Can worsen myoclonic and absence seizures
• Oxcarbazepine — Same concerns as carbamazepine
• Vigabatrin — Can worsen seizures in AS
• Tiagabine — May worsen seizures
• Phenytoin — Generally avoid in generalised epilepsy syndromes
• Gabapentin/Pregabalin — May worsen myoclonic seizures

Non-Pharmacological Approaches

Status Epilepticus Management

• Follow standard paediatric status epilepticus protocols
• AS patients may have prolonged seizures — low threshold for rescue medication
• Parents should have emergency rescue medication (buccal midazolam, rectal diazepam)
• Hospital protocol should be documented for emergency presentations

Sleep Management

Communication and Development

Augmentative and Alternative Communication (AAC)

Key Principles:

• Start AAC early — do not wait for speech to "fail"
• Multimodal approach — combine different AAC methods
• Total communication — accept all forms of communication
• Consistent use across settings (home, school, community)
• Regular review and vocabulary expansion

Early Intervention

Behavioural Management

Safety Management

Feeding and Nutrition

Orthopaedic Management

Ongoing Surveillance

Transition to Adult Services

Key transition considerations:

• Identify adult neurology/neurodevelopmental services
• Legal decision-making arrangements (guardianship/power of attorney)
• Financial planning (benefits, trusts)
• Housing and day services
• Ongoing medical management plan
• Emergency protocols

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10. Complications

Medical Complications

Developmental/Behavioural Complications

Complications by Age

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11. Prognosis & Outcomes

Natural History

Angelman syndrome is a lifelong condition with stable disability. There is no cognitive deterioration (unlike neurodegenerative conditions), and individuals continue to learn throughout life, although at a significantly slower pace. [18]

Outcome by Domain

Prognostic Factors

Better Outcomes Associated With:

• Earlier diagnosis and intervention
• Effective seizure control
• Consistent AAC implementation
• Strong family and social support
• Access to specialised services
• Milder molecular mechanism (UPD, imprinting defect)

Poorer Outcomes Associated With:

• Refractory epilepsy
• Non-convulsive status epilepticus episodes
• Severe feeding and swallowing difficulties
• Recurrent aspiration pneumonia
• Severe scoliosis
• Limited access to services
• Larger deletions (Class I)

Emerging Therapies

Active areas of research with potential to modify the disease course: [19]

[!NOTE] Research Hope: The theoretical possibility of "unsilencing" the intact paternal UBE3A allele offers a potential therapeutic approach that is unique among neurogenetic disorders. Multiple clinical trials are ongoing or planned.

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12. Evidence & Guidelines

Key Clinical Guidelines

Landmark Studies

Evidence Levels

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13. Exam-Focused Content

Common Examination Questions

1. "What are the genetic mechanisms underlying Angelman syndrome?"
2. "How does Angelman syndrome differ from Prader-Willi syndrome?"
3. "Describe the clinical features of Angelman syndrome."
4. "What investigations would you order to confirm a diagnosis of Angelman syndrome?"
5. "How would you manage seizures in a child with Angelman syndrome?"
6. "What is the recurrence risk for Angelman syndrome?"
7. "Explain genomic imprinting and its relevance to Angelman syndrome."
8. "What are the characteristic EEG findings in Angelman syndrome?"

Viva Points

Viva Point: Opening Statement: "Angelman syndrome is a neurogenetic disorder caused by loss of function of the maternally-inherited UBE3A gene at chromosome 15q11.2-q13.1. It is characterised by severe intellectual disability, absent or minimal speech, ataxic movement disorder, seizures, and a characteristic happy demeanour with frequent laughter."

Key Facts to Cite:

• Prevalence 1:12,000 to 1:20,000 (Williams et al., 2010)
• 70% deletion, 11% UBE3A mutation, 3-7% paternal UPD, 2-3% imprinting defect
• Methylation testing first-line (80-85% sensitivity for all mechanisms)
• Seizures in 80-90%; avoid carbamazepine, vigabatrin
• Paternal silencing of UBE3A in neurons is key to pathophysiology

Model Answers

Q: A 3-year-old is referred with developmental delay, no speech, and an unusual happy demeanour with frequent laughter. What is your differential diagnosis and approach?

A: "This presentation is highly suggestive of Angelman syndrome, but I would consider a differential including other genetic causes of severe intellectual disability with absent speech, such as Rett syndrome, Pitt-Hopkins syndrome, Mowat-Wilson syndrome, and Christianson syndrome.

My approach would be:

1. Detailed history: Pregnancy, birth, developmental trajectory, seizure history, sleep pattern, feeding
2. Examination: Dysmorphic features, neurological examination focusing on tone, gait, movements
3. Investigations: First-line DNA methylation testing (MS-PCR or MS-MLPA). If abnormal, confirm AS and determine mechanism with chromosomal microarray and if needed, UBE3A sequencing. EEG would show characteristic pattern even before clinical seizures.

If Angelman syndrome is confirmed, I would:

• Refer to genetics for family counselling
• Neurology for seizure management if present
• Start early intervention with speech therapy focusing on AAC
• Discuss with family regarding prognosis and support services"

Q: What antiepileptic drugs would you use and avoid in Angelman syndrome?

A: "Seizures in Angelman syndrome are often of multiple types including myoclonic, atypical absence, and generalised tonic-clonic, requiring broad-spectrum antiepileptic drugs.

First-line options:

• Sodium valproate — effective for multiple seizure types; monitor liver function
• Levetiracetam — broad-spectrum; may cause behavioural side effects in some
• Clobazam — useful adjunct; tolerance may develop

Avoid or use with caution:

• Carbamazepine and oxcarbazepine — can worsen myoclonic and absence seizures
• Vigabatrin — may worsen seizures
• Tiagabine — may worsen seizures

For refractory cases, consider ketogenic diet or vagus nerve stimulation. Parents should have rescue medication (buccal midazolam) as prolonged seizures are common."

Common Mistakes (Fail Points)

❌ Fails in examinations include:

• Confusing Angelman (maternal) with Prader-Willi (paternal) — must know imprinting correctly
• Recommending carbamazepine for seizures in AS
• Missing the characteristic EEG pattern as a diagnostic clue
• Not knowing recurrence risks vary by mechanism
• Failing to mention AAC for communication
• Not appreciating the range of molecular mechanisms beyond deletion
• Using the deprecated term "Happy Puppet Syndrome"

High-Yield Facts for Exams

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14. Patient/Layperson Explanation

What is Angelman Syndrome?

Angelman syndrome is a rare genetic condition that affects the brain and nervous system. Children with Angelman syndrome have intellectual disability, trouble with movement and balance, difficulty speaking (most don't develop speech), and often have seizures (fits). One of the distinctive features is that affected children typically have a happy, excitable personality with frequent smiling and laughter.

Why Does It Happen?

Everyone has two copies of each gene — one from their mother and one from their father. Most genes work from both copies. However, for a small number of genes, only one copy is meant to be "switched on" depending on which parent it came from. This is called genomic imprinting.

The gene called UBE3A is one of these special genes. In brain cells, only the copy from the mother is switched on — the father's copy is naturally switched off. In Angelman syndrome, the mother's copy is missing or doesn't work. Because the father's copy is already switched off, brain cells have no working UBE3A, which causes the problems seen in the condition.

This is different from Prader-Willi syndrome, where the same area of the chromosome is affected, but it's the father's copy that's missing or not working — causing a completely different set of problems.

How is It Diagnosed?

Angelman syndrome is diagnosed with genetic tests, usually a special blood test that looks at the "imprinting pattern" of chromosome 15. This test can tell if the condition is present and often what type it is.

How is It Treated?

There is no cure for Angelman syndrome yet, but there are many ways to help:

1. Seizures: Medicines to control seizures. Some medicines that work for other types of epilepsy can actually make seizures worse in Angelman syndrome, so it's important to see a specialist.

2. Communication: Because speech is very limited, children are taught to communicate using sign language, picture symbols, or electronic devices with voices. This is called augmentative and alternative communication (AAC).

3. Physical therapy: To help with walking, balance, and movement.

4. Sleep: Many children with Angelman syndrome have trouble sleeping. Melatonin (a natural sleep hormone) and good sleep habits can help.

5. Support: Special education, therapy services, and support for the whole family are essential.

What to Expect

• Children with Angelman syndrome will need lifelong care and support
• With good care, most can live into adulthood
• Many learn to walk independently, though with an unusual gait
• Speech is very limited, but many communicate well using signs or devices
• Seizures often become easier to manage with age
• Despite challenges, people with Angelman syndrome often have a happy disposition and can enjoy life with their families

When to Seek Help

• If your child has a prolonged seizure (more than 5 minutes) — call 999/911
• If you notice new difficulties with swallowing or recurrent chest infections
• If sleep disturbance is severely affecting the family
• For genetic counselling if you are planning another pregnancy

Research and Hope

Scientists are working on new treatments that might help the brain switch on the father's copy of the UBE3A gene. This is an exciting area of research, and clinical trials are already happening. While there's no cure yet, there is real hope for treatments that could significantly improve outcomes in the future.

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15. References

Primary Guidelines & Consensus

1. Williams CA, Beaudet AL, Clayton-Smith J, et al. Angelman syndrome 2005: updated consensus for diagnostic criteria. Am J Med Genet A. 2006;140(5):413-418. doi:10.1002/ajmg.a.31074

2. Williams CA, Driscoll DJ, Dagli AI. Clinical and genetic aspects of Angelman syndrome. Genet Med. 2010;12(7):385-395. doi:10.1097/GIM.0b013e3181def138

Genetic & Molecular Studies

3. Kishino T, Lalande M, Wagstaff J. UBE3A/E6-AP mutations cause Angelman syndrome. Nat Genet. 1997;15(1):70-73. doi:10.1038/ng0197-70

4. Chamberlain SJ, Lalande M. Angelman syndrome, a genomic imprinting disorder of the brain. J Neurosci. 2010;30(30):9958-9963. doi:10.1523/JNEUROSCI.1728-10.2010

5. Mertz LG, Christensen R, Vogel I, et al. Angelman syndrome in Denmark: birth incidence, genetic findings, and age at diagnosis. Am J Med Genet A. 2013;161A(9):2197-2203. doi:10.1002/ajmg.a.36058

6. Petersen MB, Brøndum-Nielsen K, Hansen LK, Wulff K. Clinical, cytogenetic, and molecular diagnosis of Angelman syndrome: estimated prevalence rate in a Danish county. Am J Med Genet. 1995;60(3):261-262. doi:10.1002/ajmg.1320600317

Seizure Management

7. Thibert RL, Conant KD, Braun EK, et al. Epilepsy in Angelman syndrome: a questionnaire-based assessment of the natural history and current treatment options. Epilepsia. 2009;50(11):2369-2376. doi:10.1111/j.1528-1167.2009.02108.x

8. Laan LA, Renier WO, Arts WF, et al. Evolution of epilepsy and EEG findings in Angelman syndrome. Epilepsia. 1997;38(2):195-199. doi:10.1111/j.1528-1157.1997.tb01097.x

Genotype-Phenotype Correlations

9. Sahoo T, Peters SU, Madduri NS, et al. Microarray-based comparative genomic hybridization testing in deletion bearing patients with Angelman syndrome: genotype-phenotype correlations. J Med Genet. 2006;43(6):512-516. doi:10.1136/jmg.2005.036913

10. Lossie AC, Whitney MM, Amidon D, et al. Distinct phenotypes distinguish the molecular classes of Angelman syndrome. J Med Genet. 2001;38(12):834-845. doi:10.1136/jmg.38.12.834

Molecular Mechanisms

11. Bird LM. Angelman syndrome: review of clinical and molecular aspects. Appl Clin Genet. 2014;7:93-104. doi:10.2147/TACG.S57386

12. Meng L, Person RE, Beaudet AL. Ube3a-ATS is an atypical RNA polymerase II transcript that represses the paternal expression of Ube3a. Hum Mol Genet. 2012;21(13):3001-3012. doi:10.1093/hmg/dds130

13. Greer PL, Hanayama R, Bloodgood BL, et al. The Angelman syndrome protein Ube3A regulates synapse development by ubiquitinating arc. Cell. 2010;140(5):704-716. doi:10.1016/j.cell.2010.01.026

14. Burette AC, Judson MC, Li AN, et al. Subcellular organization of UBE3A in human cerebral cortex. Mol Autism. 2018;9:54. doi:10.1186/s13229-018-0238-0

Clinical Features & Management

15. Pelc K, Cheron G, Dan B. Behavior and neuropsychiatric manifestations in Angelman syndrome. Neuropsychiatr Dis Treat. 2008;4(3):577-584. doi:10.2147/ndt.s2749

16. Evangeliou A, Doulioglou V, Haidopoulou K, et al. Ketogenic diet in a patient with Angelman syndrome. Pediatr Int. 2010;52(5):831-834. doi:10.1111/j.1442-200X.2010.03118.x

17. Braam W, Didden R, Smits MG, Curfs LM. Melatonin for chronic insomnia in Angelman syndrome: a randomized placebo-controlled trial. J Child Neurol. 2008;23(6):649-654. doi:10.1177/0883073808314688

Prognosis & Adult Outcomes

18. Larson AM, Shinnick JE, Shaaya EA, et al. Angelman syndrome in adulthood. Am J Med Genet A. 2015;167A(2):331-344. doi:10.1002/ajmg.a.36864

Emerging Therapies

19. Meng L, Ward AJ, Chun S, et al. Towards a therapy for Angelman syndrome by targeting a long non-coding RNA. Nature. 2015;518(7539):409-412. doi:10.1038/nature13975

20. Margolis SS, Sell GL, Zbber MA, Bird LM. Angelman syndrome. Neurotherapeutics. 2015;12(3):641-650. doi:10.1007/s13311-015-0361-y

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Further Resources

Patient Support Organisations:

• Angelman Syndrome Foundation (US): www.angelman.org
• ASSERT (UK Angelman support): www.angelmanuk.org
• Foundation for Angelman Syndrome Therapeutics (FAST): www.cureangelman.org
• Angelman Syndrome Association Australia: www.angelmansyndrome.org.au
• Unique (Rare Chromosome Disorder Support Group): www.rarechromo.org

Research Registries:

• Global Angelman Syndrome Registry: www.angelmansyndromeregistry.org
• LADDER (Longitudinal Angelman Database and Data Exchange Registry)

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Medical Disclaimer: MedVellum content is for educational purposes and clinical reference. Clinical decisions should account for individual patient circumstances. Always consult appropriate specialists. This content does not constitute medical advice for individual patients.