ClinicalTrials.gov record NCT07417137

A Natural History Study of Angelman Syndrome

Record copied from ClinicalTrials.gov: Oct 10, 2026AI summaries generated: Aug 25, 2026

A Longitudinal Natural History Study of Adults and Children With Angelman Syndrome

StatusRecruitingThe study is currently enrolling participants. Only the study team can say whether a particular person can join.
Study typeObservationalA study in which researchers do not assign participants to a treatment or other intervention. They observe or measure what happens, which may include study visits, tests, questionnaires or a review of medical records.
Age1 year old and older
SexAll
LocationUnited States
AI summaryWhat this study is about, in plain languageShow ▾Hide ▴

AI-written from the registry record, not the study's own wording. May contain errors or omissions. Check the registry text on this page and the original record ↗ before acting on it.

This is a prospective observational study of about 40 people with genetically confirmed Angelman syndrome followed for 12 months. Participants attend five study visits over the year -- three in person (Weeks 0, 26 and 52) and two remote (Weeks 13 and 39) for developmental assessments, caregiver questionnaires, EEGs, and to wear a sleep monitor at home. The study describes how skills, behaviors, sleep, and brain activity change over one year.

What it is studying. The study is trying to describe the natural progression of Angelman syndrome over a 12-month period. It aims to measure changes in developmental skills (communication, motor abilities, adaptive behavior), behavior and sleep, and to see whether patterns in brain activity (EEG) or sleep (actigraphy) are linked with changes in symptoms over time. The data are intended to create reference information to help design and interpret future clinical trials and to support development of better diagnostic or measurement tools.

What the researchers hope to learn. Establish age-related, one-year patterns of development, behavior, seizure frequency, and sleep in people with Angelman syndrome. Identify EEG and actigraphy biomarker patterns that relate to clinical changes and provide normative data to inform future trial design and diagnostic or measurement tool development.

What this study is about

The study's own summary, as published on ClinicalTrials.gov. Underlined terms have a short explanation.

The goal of this observational study is to learn about the natural progression of Angelman syndrome (AS) in children and adults with a confirmed genetic diagnosis of AS. The main questions it aims to answer are:

  • How do developmental skills, such as communication, motor abilities, and adaptive behaviors, change over a 1-year period in people with AS?
  • Are there specific patterns in brain activity or sleep that are associated with changes in AS symptoms over time?

Participants will:

  • Attend 3 in-person and 2 virtual study visits over 1 year for assessments.
  • Complete tests and questionnaires about development, behaviors, and sleep with the help of their caregivers.
  • Undergo electroencephalograms (EEGs) to measure brain activity and wear a sleep-monitoring device at home (to collect actigraphy data).

Eligibility

The criteria exactly as listed on ClinicalTrials.gov. Only the study team can say whether they apply to you.

Inclusion criteria

  • The participant has a primary clinical diagnosis of Angelman syndrome with documented genetic variation(s) affecting the function of the UBE3A gene within the human 15q11.2-q13.3 locus. Co-occurring conditions (e.g., autism spectrum disorder, cerebral palsy, intellectual disability) are permitted; however, Angelman syndrome must be the primary clinical diagnosis.
  • The participant is male or female (assigned sex at birth) and aged ≥1 year at the initial study visit.
  • The participant has a study partner who meets the study partner criteria below.
  • The participant, if unable to provide informed consent, has an appropriate surrogate who is at least 18 years of age and willing and able to provide informed consent on behalf of the participant in accordance with current International Council for Harmonisation (ICH) guidelines and applicable institutional regulations.
  • Individuals must satisfy the following criteria to be enrolled as study partners:
  • The study partner is a parent or primary caregiver who is at least 18 years of age.
  • The study partner has consistent contact with the participant and, in the opinion of the investigator, is sufficiently knowledgeable about the participant's ongoing condition to provide accurate and current information.
  • The study partner has sufficient English-language proficiency to complete study partner assessments.
  • The study partner is willing and able to provide informed consent on their own behalf in accordance with ICH guidelines and applicable institutional regulations.
  • The study partner is, in the opinion of the investigator, reliable and competent; willing and able to accompany the participant to all study visits and comply with study procedures; reachable by telephone or email as needed; and sufficiently knowledgeable about the participant's ongoing condition(s) to provide accurate and current information regarding the participant's health and well-being.

Exclusion criteria

  • The participant has at least one additional known genetic abnormality outside the human 15q11.2-q13.3 locus causing a probable or known developmental disability.
  • At least one standard-of-care treatment (medication or adjunctive therapy) used by the participant was changed during the 28 days (4 weeks) prior to the first study visit. Treatments include, but are not limited to, doses of anti-epileptic medications, behavioral management medications, sleep medications, gabapentin, cannabidiol, special diets, supplements, speech therapy, occupational therapy, applied behavioral analysis (ABA), psychosocial interventions, physical therapy, or nutritional support.
  • The participant has unstable epilepsy, defined as having an emergency department visit or hospitalization for seizure-related concerns within the 28 days (4 weeks) preceding the initial study visit.
  • The participant is of childbearing potential and is either pregnant, breastfeeding, or not using an adequate method of contraception; abstinence is acceptable.
  • The participant has a clinically relevant history of malignancy; clinically significant abnormal test results; clinically significant cardiovascular, hematologic, hepatic, muscular, neurologic, or renal disease; or has experienced other clinical events which, in the opinion of the investigator, render participation unsuitable.
  • The participant has a lifetime history of treatment with any cell- or gene-based therapy, including antisense oligonucleotides or gene-editing therapies.
  • The participant has received any investigational therapy other than a cell- or gene-based therapy within 28 days or 5 half-lives (whichever is longer) preceding the initial study visit.
  • The participant is currently enrolled or plans to enroll in an interventional study involving an investigational agent or device during the planned observation period.
  • The participant has a known contraindication to electroencephalography, actigraphy, or any other study procedure described in the schedule of assessments.
  • The participant or study partner is, in the opinion of the investigator, unsuitable for participation in any other way, including an inability to fulfill study requirements.

Study description and what participation involves

The study's detailed description, as published on ClinicalTrials.gov.

Detailed description from the registry
  • Longitudinal, natural history study of 40 individuals with AS, enriched for a child and adolescent population.
  • Seeks to establish normative data to inform future design and interpretation of clinical trials for AS and to support the development of more precise diagnostic tools and targeted therapeutic interventions for AS.
  • Track adaptive behavior, communication, challenging behaviors, general health, overall disease severity, and common co-occurring conditions (including epilepsy and sleep disturbances) through standardized assessments.
  • Biomarker data collected through EEGs and actigraphy recordings will be analyzed to assess age-related changes in clinical outcomes and neurophysiological measures.
  • Participants will attend up to 5 study visits over the course of 12 months: Week 0, Week 13, Week 26, Week 39, Week 52. Weeks 0, 26, 52 will be in-person. Weeks 13 and 39 will be remote.
AI summaryWhat participation may involve, in plain languageShow ▾Hide ▴

AI-written from the registry record, not the study's own wording. May contain errors or omissions. Check the registry text on this page and the original record ↗ before acting on it.

Participants attend up to five visits over 12 months (Weeks 0, 13, 26, 39 and 52), about every 3 months. Three of these are in person (Weeks 0, 26 and 52) and two are remote (Weeks 13 and 39). At visits they complete standardized developmental, behavior, and health assessments with caregiver help and clinician-rated scales; they will have electroencephalograms (EEGs) and caregivers will complete questionnaires and diaries (for sleep and seizures). Participants will wear a home sleep-monitoring device (actigraphy) between visits to collect sleep data. If a participant cannot give consent, an appropriate surrogate (≥18 years) may provide consent on their behalf.

How the study is structured. A prospective, observational cohort study. Participants have five scheduled visits over 52 weeks (Week 0, 13, 26, 39, 52) for standardized developmental tests and caregiver-completed questionnaires. Brain activity is recorded with EEG, and participants wear a home sleep-monitoring device (actigraphy) to collect sleep data between visits. No investigational treatments are assigned. Note: adults (18+) are limited to a small number of slots, and children aged 1-12 are enrolled into a prioritized cohort first.

Questions you could ask

These questions are suggestions for a conversation with the study team or your own clinician, not advice.

  • This is an observational study, so the study itself gives no treatment. What would taking part involve for me, and would it change my usual care?
  • The listed sites are in United States. Is any of them reachable for me, and does the study help with travel?
  • Which of the eligibility criteria would need to be checked with tests before I could join?

More on Angelman syndrome

Clinical trials11 trials listed for Angelman syndromeEvery trial the registry lists for Angelman syndrome, with recruitment status, phase and sites, updated from ClinicalTrials.gov.See all trials →Research updatesWhat changed in Angelman syndrome researchLatest monthly update: September 2026. Includes: Seizure frequency. New research summarized each month in plain language, with links to every source paper.Read the latest update →

Important dates

Study start
August 2026 (estimated)
Primary completion
September 2028 (estimated)
Study completion
September 2029 (estimated)
Target enrollment
40 participants (estimated)
Last updated on registry
Aug 21, 2026
Data verified
Oct 10, 2026

Sponsor and research team

The lead sponsor funds and oversees the trial. A pharmaceutical or biotech company sponsor typically means the study is testing that company's drug or device; a hospital, university, or government agency usually indicates investigator-initiated or publicly funded research.

Lead sponsor
Massachusetts General Hospital
Principal investigator
Christopher Keary, Behavioral Director (Angelman Syndrome Clinic) & Staff Psychiatrist (Lurie Center for Autism)
Massachusetts General Hospital
Collaborators
  • Astellas Pharma Global Development, Inc.

Central study contact

If you're interested in participating, the central contact can answer general questions about the study — including eligibility requirements and how to find a recruiting site near you. Actual eligibility is determined by the site's medical team.

Participating sites (1)

Terms used on this page · explanations by MedicalUpdates.ai

informed consent
The process of explaining a study, including its risks and what participation involves, so that a person can decide freely whether to take part. Consent is usually documented in writing, and a participant can choose to leave the study later.
childbearing potential
Studies often ask participants who could become pregnant, or could father a child, to use contraception during the study and for a period afterwards, because the effect of the treatment on a pregnancy is unknown.
investigational
A treatment that is being tested and has not been approved for this use. It may be approved for a different condition. Being studied does not mean it works or is available outside the study.
5 half-lives
The time it takes for the amount of a drug in the body to fall by half. 'Five half-lives' is often used as the point at which a previous drug has essentially left the body.
interventional study
A study in which researchers assign participants to one or more interventions, such as a drug, procedure, device, behavioural programme or other approach, to measure their effects.
contraindication
A reason a particular test or treatment should not be used for a person, for example a metal implant that rules out an MRI scan.
Inclusion Criteria
The conditions a person must meet to be considered for the study, for example a confirmed diagnosis, an age range or a test result.
Exclusion Criteria
The conditions that rule a person out even if they meet the inclusion criteria, for example other illnesses, certain medicines or pregnancy.
natural history study
A study that follows how a condition changes over time without assigning an experimental treatment. It may involve study visits and tests, and is often used to plan future trials.
Biomarker
Something measurable in the body, such as a blood test result or an imaging finding, that indicates how a condition or treatment is behaving.

The study record on this page is reproduced from ClinicalTrials.gov, a database of the U.S. National Library of Medicine, where it was submitted by the study sponsor. MedicalUpdates.ai does not own this content, is not affiliated with or endorsed by ClinicalTrials.gov, NIH, or the U.S. Government, and does not verify the record. Plain-language notes, the glossary and the questions above are added by this site; text in the boxes marked "AI summary" was written by an AI model and may contain errors. Registry records change over time. Check the original record for the current version and discuss eligibility or participation with a qualified healthcare professional.

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