An observational study in Down Syndrome, sponsored by National Institute of Allergy and Infectious Diseases (NIAID). Recruiting at 1 site in United States. Open to participants aged 1 Year to 120 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-10-29.
Sponsored by National Institute of Allergy and Infectious Diseases (NIAID) · Observational
Background:
Down syndrome is a genetic disorder that can cause heart defects and other problems in the body. People with Down syndrome are more likely to have infections, autoimmunity, and blood diseases. Some may need surgery to treat congenital heart problems. During this surgery, doctors sometimes remove part of the thymus. The thymus is an organ that plays a role in immune function. People who have had part of their thymus removed may get sick more often than others do.
Objective:
This natural history study will gather data about how removing part of the thymus affects the health of people with Down syndrome.
Eligibility:
People aged 1 year and older with Down syndrome. The study will include both people who have, and those who have not had, surgery to remove part of their thymus. Healthy relatives are also needed.
Design:
Participants with Down syndrome will have clinic visits at least once a year for 15 years.
At each visit they will have a physical exam. They will give blood and stool samples. They will have tests of their heart and lung function.
Participants aged 18 years or older may have at least 1 imaging scan: They will lie on a table that slides into a donut-shaped machine. The machine uses X-rays to take pictures of the inside of the body.
Participants who have tissue samples collected from their bodies (biopsies) taken during the study may have extra tissue taken for research.
Healthy relatives will also have visits once a year for 15 years. They will only have a physical exam and provide blood and stool samples.
...
Study Description:
This is a longitudinal observational study of individuals with trisomy 21 (T21) to gather data on the immune function in order to identify clinical and laboratory signatures of immunodeficiency and/or immune dysregulation, characterize their pathophysiology, evaluate their progression and evolution over time, and analyze the impact of immunomodulatory and immunosuppressive treatment. In order to assess the possible impact of thymectomy on immune dysfunction and on the risk of developing autoimmunity, malignancies, and/or increased susceptibility to infections, both individuals who have had previous thymectomy and those who have not received this procedure will be included. Affected participants will have a baseline visit and follow-up study visits every year (starting from baseline) to assess their health and collect biospecimens (including but not limited to blood). Additional visits can also be scheduled as clinically indicated. Data and excess biospecimens from routine clinical care may also be collected and used for research. Unaffected relatives who live in the same household as the corresponding affected participant will be enrolled as controls and will undergo yearly blood collection and optional yearly stool, buccal swab, and saliva collections for comparison of microbiome and immunological data.
Objectives:
Primary Objectives:
Secondary Objectives:
- Identify cellular and molecular mechanisms of immune dysfunction in individuals with T21
Endpoints:
Primary Endpoints:
Secondary Endpoints:
Exploratory Endpoints:
438 studies on the registry are indexed under Down Syndrome; 99 are open to participants now.
This study's planned enrollment of 700 is above the median of 158 across 145 observational studies indexed under Down Syndrome.
Browse Down Syndrome studies →National Institute of Allergy and Infectious Diseases (NIAID) is the lead sponsor of 2,446 studies on the registry; 179 are open to participants now.
Of its 405 completed or terminated interventional studies of FDA-regulated products, 302 (75%) have results posted.
Counted across the registry records on this site, refreshed daily.
Participants will be selected in an equitable manner from the available pool of potentially eligible individuals, without regard to factors such as sex, race, ethnicity, socioeconomic status, etc. To facilitate recruitment, the study will be registered in clinicaltrials.gov and will be shared with T21 advocacy groups.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
In order to be eligible to participate in this study, an individual must meet all of the following criteria:
1. Aged >=1 year.
2. Willingness to allow storage of specimens and data for future research.
Additional Inclusion Criteria for Affected Participants
Additional Inclusion Criteria for Unaffected Relatives
EXCLUSION CRITERIA:
An individual who meets any of the following criteria will be excluded from participation in this study:
1. Any condition that, in the judgment of the investigator, may put the participant at undue risk or make them unsuitable for participation in the study.
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants aged \>=1 year old who have T21
Participants aged \>=1 year old who are related to a participant with T21
Frequency of T21 individuals with laboratory evidence of autoantibodies
Describe the immune correlates of clinical endpoints (infections, autoimmunity, malignancies), and their cumulative frequency over time, in individuals with T21. Describe the possible impact of previous thymectomy on the incidence of clinical manifestations of immune deficiency and immune dysregulation, and on laboratory parameters of immune function
Time frame: Through end of study
Number and type of autoimmune manifestations/year
Describe the immune correlates of clinical endpoints (infections, autoimmunity, malignancies), and their cumulative frequency over time, in individuals with T21. Describe the possible impact of previous thymectomy on the incidence of clinical manifestations of immune deficiency and immune dysregulation, and on laboratory parameters of immune function
Time frame: Through end of study
Frequency of individuals with abnormal T and B cell counts and immunoglobulin serum levels
Describe the immune correlates of clinical endpoints (infections, autoimmunity, malignancies), and their cumulative frequency over time, in individuals with T21. Describe the possible impact of previous thymectomy on the incidence of clinical manifestations of immune deficiency and immune dysregulation, and on laboratory parameters of immune function
Time frame: Through end of study
Proportion of T21 individuals with malignancies by age group (compared to the general population), and type of malignancies
Describe the immune correlates of clinical endpoints (infections, autoimmunity, malignancies), and their cumulative frequency over time, in individuals with T21. Describe the possible impact of previous thymectomy on the incidence of clinical manifestations of immune deficiency and immune dysregulation, and on laboratory parameters of immune function
Time frame: Through end of study
Nature of infections (bacterial, viral, fungal, opportunistic pathogens) requiring hospitalization
Describe the immune correlates of clinical endpoints (infections, autoimmunity, malignancies), and their cumulative frequency over time, in individuals with T21. Describe the possible impact of previous thymectomy on the incidence of clinical manifestations of immune deficiency and immune dysregulation, and on laboratory parameters of immune function
Time frame: Through end of study
Incidence of severe infections requiring hospital admission (number of admissions/year; number of days of hospitalization/year)
Describe the immune correlates of clinical endpoints (infections, autoimmunity, malignancies), and their cumulative frequency over time, in individuals with T21. Describe the possible impact of previous thymectomy on the incidence of clinical manifestations of immune deficiency and immune dysregulation, and on laboratory parameters of immune function
Time frame: Through end of study
Levels of specific antibodies to immunization antigens
Identify cellular and molecular mechanisms of immune dysfunction in individuals with T21
Time frame: Through end of study
Proportion of T cells exhibiting expression of exhaustion markers
Identify cellular and molecular mechanisms of immune dysfunction in individuals with T21
Time frame: Through end of study
Diversity of T-cell receptor repertoire, measured as proportion of CD4+ and CD8+ cells expressing distinct TRBV families
Identify cellular and molecular mechanisms of immune dysfunction in individuals with T21
Time frame: Through end of study
Distribution of subsets of Th, T follicular helper, and Treg cells
Identify cellular and molecular mechanisms of immune dysfunction in individuals with T21
Time frame: Through end of study
Proportion of dysreactive B cell subsets (defined as CD19(hi) CD21(low) CD38(low) B cells)
Identify cellular and molecular mechanisms of immune dysfunction in individuals with T21
Time frame: Through end of study
Plan to share: Yes — Individual subjects' clinical and laboratory metadata will be de-identified. Each subject is given a unique patient code, and the metadata will be imported in ImmPort.
Time frame: In preparation of publication, data will be deposited on data sharing platforms (such as Zenodo, Github, ImmPort, dbGaP) with an embargo until publication date, and access codes that will be made available to reviewers of the manuscript.
Access criteria: Unpublished data will be made available upon written request and according to a data sharing agreement approved by the Office of Technology Transfer and Intellectual Property, National Institutes of Health.@@@@@@When included in publications, these data will be made available as part of the Supporting Information associated with the manuscript.@@@@@@
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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