Disease Directory Severe Combined Immunodeficiency
Immune

Severe Combined Immunodeficiency

Also known as: SCID, bubble boy disease, ADA-SCID, X-linked SCID

Prevalence

1 in 50,000-100,000 live births

Onset

Neonatal to infancy (typically first 3-6 months of life)

Type

Combined primary immunodeficiency

Gene

IL2RG, ADA, RAG1, RAG2 (multiple)

About Severe Combined Immunodeficiency

Severe Combined Immunodeficiency encompasses a heterogeneous group of inherited disorders marked by profound defects in both T-cell and B-cell immunity, rendering affected infants susceptible to life-threatening infections by bacteria, viruses, and fungi. Newborn screening programs have enabled earlier identification, dramatically improving outcomes when hematopoietic stem cell transplantation or gene therapy is initiated before infectious complications occur. Without definitive treatment, SCID is uniformly fatal in early childhood.

Common Clinical Features

Recurrent and severe infections beginning in infancy Failure to thrive and poor weight gain Chronic diarrhea and oral candidiasis Absent or minimal lymph nodes and tonsils Opportunistic infections (Pneumocystis, CMV) Severe reactions to live viral vaccines Maternal engraftment graft-versus-host disease

Clinical Trial Eligibility Tips

What to know before applying to Severe Combined Immunodeficiency trials.

Gene therapy trials for ADA-SCID and X-linked SCID typically enroll infants without a matched sibling donor; confirm HLA typing results and donor search status before applying

Most interventional trials require patients to be free of active infection at enrollment; timing of application relative to current infectious status is critical

Newborn screening detection status (positive vs. incidental diagnosis) may affect eligibility in natural history studies — report NBS results accurately

Patient Resources

Patient Organization

Immune Deficiency Foundation

Visit website ↗

Natural History Registry

USIDNET Registry

Join registry ↗

Orphanet

European reference resource for rare diseases (ORPHA:183660)

View on Orphanet ↗

NORD

National Organization for Rare Disorders

Search NORD ↗

Find recruiting Severe Combined Immunodeficiency trials

Search 500,000+ studies from ClinicalTrials.gov, filtered for Severe Combined Immunodeficiency. Updated daily.

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