Severe combined immunodeficiency (SCID), sometimes called “bubble boy” disease, is a group of rare inherited disorders in which a baby’s immune system cannot fight infections. Without treatment it is usually fatal in the first year, but when caught at birth and treated early, most babies survive and do well, which is exactly why it is screened for.
What causes SCID
SCID is caused by changes in any of several genes (most commonly IL2RG, which is X-linked, as well as ADA and others) that are needed to build working immune cells. Most forms are inherited, and a baby can be affected even with no family history.
How newborn screening detects SCID
SCID is screened for in all U.S. states using the TREC test (T-cell receptor excision circles), which measures markers of healthy T-cell production in a dried blood spot. A low result is followed by confirmatory immune testing. Because newborns with SCID look healthy at birth, screening is what makes early detection possible.
How SCID is treated
SCID is treatable, and outcomes are dramatically better when treatment starts early, before infections occur. Options include a stem cell (bone marrow) transplant, gene therapy for certain types, and enzyme replacement for ADA-deficient SCID. Protecting the baby from infection in the meantime is critical.
Related conditions beyond the standard panel
Standard newborn screening is designed to catch SCID specifically, but it does not detect most other primary immunodeficiencies. Conditions such as agammaglobulinemia, Wiskott-Aldrich syndrome, and chronic granulomatous disease are generally not on state panels. Genomic screening can assess the genes linked to a much broader set of immune disorders, giving a fuller picture than the TREC test alone.
How genomic screening fits in
State screening does an excellent job of catching SCID. Fore Genomics’ at-home cheek-swab screen looks at the genes tied to more than 1,000 clinically actionable childhood conditions, including immune disorders beyond SCID, sequenced in CLIA-certified and CAP-accredited labs with board-certified genetic counselor support. See what we screen for or start screening.
Frequently asked questions
Is SCID on every state’s newborn screening panel?
Yes. SCID is screened for in all U.S. states using the TREC test.
Can a baby with SCID be cured?
Many babies treated early, often with a stem cell transplant or gene therapy, go on to live healthy lives. Early detection before infections is key.
Medically reviewed by Fore’s Clinical Team. This article is for general educational purposes and is not medical advice. Sources: HRSA Newborn Screening; Immune Deficiency Foundation.