Combined T- and B-cell immunodeficiencies (SCID)
SCID as a newborn-screened emergency (TRECs), the immunophenotypes and genes, protecting the infant before transplant, HSCT outcomes, and the less severe combined defects that adult physicians meet (CD40L, Wiskott-Aldrich, ataxia-telangiectasia, DOCK8, late-onset combined immunodeficiency).
Tier 1Condition
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- SCID is the most severe primary immunodeficiency: no functional T cells, so no effective cellular or antibody immunity. Without HSCT it is usually fatal in the first year of life.
- Australia screens every newborn for SCID with TRECs on the bloodspot card, so most cases are now found before infection.
- SCID is a medical emergency: isolate, no live vaccines, irradiated CMV-negative blood, PJP prophylaxis, immunoglobulin replacement, and HSCT as early as possible.
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Sources
- Primary Immunodeficiencies (PID) Clinical UpdateAU/NZASCIA (Australasian Society of Clinical Immunology and Allergy), 2025
- Newborn bloodspot screening, what is screened in the programAU/NZAustralian Government Department of Health, Disability and Ageing, Page updated 15 October 2026
- Human inborn errors of immunity: 2024 update on the classification from the International Union of Immunological Societies Expert Committee (Poli MC et al. J Hum Immun 2025;1(1):e20250003)International Union of Immunological Societies, 2024 update (published April 2025)
- The 2024 update of IUIS phenotypic classification of human inborn errors of immunity (Bousfiha A et al. J Hum Immun 2025;1(1):e20250002)International Union of Immunological Societies, 2024 update (published April 2025)
- Transplantation outcomes for severe combined immunodeficiency, 2000-2009 (Pai SY et al. N Engl J Med 2014;371:434-46)Primary Immune Deficiency Treatment Consortium, NEJM, 2014
- Establishing the diagnosis of severe combined immunodeficiency: the PIDTC 2022 definitions (Dvorak CC et al. J Allergy Clin Immunol 2023;151:539-46)Primary Immune Deficiency Treatment Consortium, 2022 definitions (published 2023)
- Late-onset combined immune deficiency: a subset of common variable immunodeficiency with severe T cell defect (Malphettes M et al. Clin Infect Dis 2009;49:1329-38)Clinical Infectious Diseases, 2009
- Australian Immunisation Handbook, close contacts of people who are immunocompromisedAU/NZAustralian Technical Advisory Group on Immunisation, updated 13 March 2026
- Last updated
- 14 November 2026
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