Overview
T-B+ severe combined immunodeficiency (SCID) is a very serious inherited condition that affects the immune system. In this form of SCID, the body cannot make working T cells, which are a critical type of white blood cell needed to fight infections. However, B cells (another type of immune cell) are present in normal or increased numbers, though they do not work properly without T cell help. The 'T-B+' name describes this pattern: T cells are absent or very low, while B cells are present. Babies with T-B+ SCID usually appear healthy at birth but quickly develop life-threatening infections within the first few months of life. Common problems include persistent thrush (oral yeast infections), chronic diarrhea, pneumonia, skin rashes, and failure to thrive (poor growth and weight gain). Without treatment, even common childhood illnesses like colds or chickenpox can become fatal. The most well-known cause of T-B+ SCID is a mutation in the IL2RG gene on the X chromosome, which causes X-linked SCID (also called 'bubble boy disease'). Other causes include mutations in the JAK3 gene or the IL7R gene. Treatment has improved dramatically over the past few decades. Hematopoietic stem cell transplant (bone marrow transplant) is the standard treatment and can be curative, especially when performed early in life. Gene therapy has also become available for some forms. Newborn screening programs that detect SCID through the TREC assay have greatly improved early diagnosis and outcomes.
Also known as:
Key symptoms:
Frequent and severe infections starting in early infancyPersistent oral thrush that does not respond to treatmentChronic diarrheaFailure to gain weight or grow normallyPneumonia or other serious lung infectionsSkin rashes or eczema-like rashesEar infections that keep coming backInfections caused by organisms that usually do not harm healthy people (opportunistic infections)Severe diaper rashAbsence of tonsils or lymph nodesInfections that do not improve with standard antibioticsBloodstream infections (sepsis)Liver or spleen enlargement from infections
Variable
Can be inherited in different ways depending on the underlying gene
Infantile
Begins in infancy, roughly 1 month to 2 years old
FDA & Trial Timeline
3 eventsNational Institute of Allergy and Infectious Diseases (NIAID) — PHASE1, PHASE2
Center for International Blood and Marrow Transplant Research — PHASE2
National Institute of Allergy and Infectious Diseases (NIAID) — PHASE1, PHASE2
Data sourced from FDA regulatory filings and ClinicalTrials.gov. Updated periodically.
Treatments
No FDA-approved treatments are currently listed for T-B+ severe combined immunodeficiency.
3 clinical trialsare actively recruiting — trials can provide access to cutting-edge therapies.
View clinical trials →Rare Disease Specialist
Rare Disease Specialist
Treatment Centers
8 centersBaylor College of Medicine Rare Disease Center ↗
Baylor College of Medicine
📍 Houston, TX
🏥 NORDStanford Medicine Rare Disease Center ↗
Stanford Medicine
📍 Stanford, CA
🔬 UDNNIH Clinical Center Undiagnosed Diseases Program ↗
National Institutes of Health
📍 Bethesda, MD
🔬 UDNUCLA UDN Clinical Site ↗
UCLA Health
📍 Los Angeles, CA
🔬 UDNBaylor College of Medicine UDN Clinical Site ↗
Baylor College of Medicine
📍 Houston, TX
🔬 UDNHarvard/MGH UDN Clinical Site ↗
Massachusetts General Hospital
📍 Boston, MA
🏥 NORDMayo Clinic Center for Individualized Medicine ↗
Mayo Clinic
📍 Rochester, MN
👤 Mayo Clinic Center for Individualized Medicine
🏥 NORDUCLA Rare Disease Day Program ↗
UCLA Health
📍 Los Angeles, CA
Travel Grants
No travel grants are currently matched to T-B+ severe combined immunodeficiency.
Community
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Caregiver Resources
NORD Caregiver Resources
Support, advocacy, and financial assistance for caregivers of rare disease patients.
Mental Health Support
Rare disease caregiving can be isolating. Connect with counseling and peer support.
Family & Caregiver Grants
Financial assistance programs specifically for caregivers of rare disease patients.
Social Security Disability
Learn how rare disease patients may qualify for SSDI/SSI benefits.
Questions for your doctor
Bring these to your next appointment
- Q1.What specific gene mutation is causing my child's SCID, and does this affect treatment options?,How soon should we proceed with a bone marrow transplant, and what type of donor is best?,Is gene therapy an option for my child's specific type of T-B+ SCID?,What infections should we watch for, and when should we go to the emergency room?,Will my child need lifelong immunoglobulin replacement therapy after transplant?,What are the long-term side effects of the conditioning chemotherapy used before transplant?,Should other family members be tested to see if they are carriers of this condition?
Common questions about T-B+ severe combined immunodeficiency
What is T-B+ severe combined immunodeficiency?
T-B+ severe combined immunodeficiency (SCID) is a very serious inherited condition that affects the immune system. In this form of SCID, the body cannot make working T cells, which are a critical type of white blood cell needed to fight infections. However, B cells (another type of immune cell) are present in normal or increased numbers, though they do not work properly without T cell help. The 'T-B+' name describes this pattern: T cells are absent or very low, while B cells are present. Babies with T-B+ SCID usually appear healthy at birth but quickly develop life-threatening infections with
At what age does T-B+ severe combined immunodeficiency typically begin?
Typical onset of T-B+ severe combined immunodeficiency is infantile. Age of onset can vary across affected individuals.
Are there clinical trials for T-B+ severe combined immunodeficiency?
Yes — 3 recruiting clinical trials are currently listed for T-B+ severe combined immunodeficiency on UniteRare. See the clinical trials section on this page for phase, sponsor, and site details sourced from ClinicalTrials.gov.
Which specialists treat T-B+ severe combined immunodeficiency?
5 specialists and care centers treating T-B+ severe combined immunodeficiency are listed on UniteRare, sourced from ClinicalTrials.gov principal investigators, published research, and the NPPES NPI registry.