Observational Study to Characterize Biomarkers and Disease Progression in Participants With Methyl CpG Binding Protein 2 (MECP2) Duplication Syndrome

April 6, 2026 updated by: Ionis Pharmaceuticals, Inc.

A Prospective and Retrospective Observational/Non-interventional Study to Characterize Biomarkers and Disease Progression in Patients With MECP2 Duplication Syndrome

The purpose of the study is to prospectively assess longitudinal changes in biomarkers (MECP2, potential biomarkers of target engagement and disease activity) in cerebrospinal fluid (CSF) and blood; characterize longitudinal changes in performance on clinical scales (clinician-reported measures of neurodevelopment and functioning) and caregiver-reported outcome assessments (communication, gastrointestinal, social-emotional-adaptive behavioral measures); evaluate longitudinal changes in caregiver-reported health-related quality-of-life measures; and assess the frequency, type, and severity of seizures over time.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Terminated

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Detailed Description

This is a multi-center, non-randomized, non-interventional prospective and retrospective study in up to 40 participants with MECP2 duplication syndrome (MDS) who can undergo general anesthesia or conscious sedation to collect fluid biomarkers (CSF and blood), undergo electrophysiological assessments (electroencephalogram [EEG], evoked potentials [EP], pupillometry), clinical assessments and caregiver reported outcomes measures, to be used in support of the development of therapies for MDS. The study duration for each participant will be approximately 110 weeks.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Observational

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
29

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • United States
    • California
      • San Diego, California, United States, 92123
        • UCSD - Rady Children's Hospital
    • Minnesota
      • Saint Paul, Minnesota, United States, 55101
        • Gillette Children's Specialty Healthcare
    • Pennsylvania
      • Philadelphia, Pennsylvania, United States, 19104
        • Children's Hospital of Philadelphia
    • Tennessee
      • Nashville, Tennessee, United States, 37203
        • Vanderbilt University Medical Center
    • Texas
      • Houston, Texas, United States, 77030
        • Baylor College of Medicine

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Child
  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

Participants who have a diagnosis of MDS with genetic confirmation of MECP2 duplication or triplication will be enrolled into this study.

Description

Key Inclusion Criteria

  • Participant has a diagnosis of MDS with genetic confirmation of MECP2 duplication (or triplication)
  • Participant has a parent or caregiver (CG) ≥ 18 years old capable of providing informed consent (signed and dated), and able to attend all scheduled study visits and provide feedback regarding the participant's symptoms and performance as described in the protocol and be able to comply with all study requirements and activities
  • Male ≥ 1 month and ≤ 65 years of age
  • No contraindications for lumbar puncture (LP)'s, blood draws, sedation (if necessary) or other study activities
  • Medically stable to complete the study and will tolerate sedation or general anesthesia and other study activities

Key Exclusion Criteria

  • Clinically significant abnormalities in medical history (e.g., clinically significant renal, hepatic, or cardiac abnormalities; major surgery within 3 months of screening) or upon physical examination that could potentially impact the NH of MDS
  • Unwillingness or inability to comply with study procedures, including follow up, as specified by this protocol, or unwillingness to cooperate fully with the Investigator
  • Treatment with an investigational drug, gene therapy, stem cell therapy, biological agent, or device within 30 days of screening, or 5 half-lives of investigational agent, whichever is longer (participants cannot be concurrently enrolled in NH00006 and ION440-CS1).

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

Cohorts and Interventions

Group / Cohort

Group / Cohort

A group or subgroup of participants in an observational study that is assessed for biomedical or health outcomes.
MECP2 Duplication Syndrome Disease Participants
Participants with a diagnosis of MDS with genetic confirmation of MECP2 duplication (or triplication) will undergo CSF and blood collection, electrophysiological and clinical assessments, up to Week 104 as a part of prospective study. Each participant's medical and family history data will be collected retrospectively from available medical notes and charts, from birth up to the end of the study (up to 110 weeks). Participants will have an option to participate in an optional sub-study that will capture pre-defined list of activities at home video.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Change From Baseline in MeCP2 in the CSF
Time Frame: Baseline and on Weeks 13, 26, 39, 52
Baseline and on Weeks 13, 26, 39, 52
Laboratory biomarkers for MECP2 Duplication
Time Frame: Baseline and on Weeks 13, 26, 39, 52
Proteomic analysis of plasma samples to determine biomarkers of disease progression.
Baseline and on Weeks 13, 26, 39, 52
Change From Baseline in MECP2 Duplication Syndrome Severity Scale Across All Domains
Time Frame: Baseline and on Weeks 13, 26, 39, 52, 78, 104
Baseline and on Weeks 13, 26, 39, 52, 78, 104
Change From Baseline in the Revised Motor Behavioral Assessment
Time Frame: Baseline and on Weeks 13, 26, 39, 52, 78, 104
Baseline and on Weeks 13, 26, 39, 52, 78, 104
Change From Baseline in the Bayley Scales of Infant and Toddler Development, 3rd Edition
Time Frame: Baseline and on Weeks 13, 26, 39, 52, 78, 104
Baseline and on Weeks 13, 26, 39, 52, 78, 104
Change From Baseline in Vineland Adaptive Behavior Scales 3rd Edition
Time Frame: Baseline and on Weeks 13, 26, 39, 52, 78, 104
Baseline and on Weeks 13, 26, 39, 52, 78, 104
Change From Baseline in Observer Reported Communication Ability Measure
Time Frame: Baseline and on Weeks 13, 26, 39, 52, 78, 104
Baseline and on Weeks 13, 26, 39, 52, 78, 104
Change From Baseline in Quality-of-Life Inventory-Disability Score
Time Frame: Baseline and on Weeks 13, 26, 39, 52, 78, 104
Baseline and on Weeks 13, 26, 39, 52, 78, 104
Change From Baseline in the Frequency of Seizures
Time Frame: Baseline and on Weeks 13, 26, 39, 52, 78, 104
Baseline and on Weeks 13, 26, 39, 52, 78, 104
Change From Baseline in Global Assessment of Severity of Epilepsy Scale Score
Time Frame: Baseline and on Weeks 13, 26, 39, 52, 78, 104
Baseline and on Weeks 13, 26, 39, 52, 78, 104

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Time Frame
Change From Baseline in Auditory Evoked Potential
Time Frame: Baseline and on Weeks 13, 26, 39, 52, 78, 104
Baseline and on Weeks 13, 26, 39, 52, 78, 104
Change From Baseline in Visual Evoked Potentials
Time Frame: Baseline and on Weeks 13, 26, 39, 52, 78, 104
Baseline and on Weeks 13, 26, 39, 52, 78, 104
Perform a retrospective chart review of the participant's medical history and family history to characterize the natural history of MDS
Time Frame: Baseline and on Weeks 13, 26, 39, 52, 78, 104
Baseline and on Weeks 13, 26, 39, 52, 78, 104

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Ionis Pharmaceuticals, Inc.

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
October 3, 2023

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
October 7, 2025

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
October 7, 2025

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
August 9, 2023

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
August 23, 2023

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
August 28, 2023

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
April 9, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 6, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
April 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • NH00006

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Ionis may share anonymized individual participant data, aggregated clinical data, and other types of data that support the results in this study. Data requests from qualified researchers will be considered once all three of the following criteria are met: (1) 12 months from marketing approval of the study drug in both the United States and European Union; (2) 18 months from conclusion of the study; and (3) 6 months from publication of study article. Access would be via a secure environment and is contingent upon approval of a research proposal and entry into an appropriate data use agreement. Requests to access data can be submitted via the website https://vivli.org/ourmember/ionis/.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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