Last reviewed: 22 May 2021
Last updated: 15 Jan 2020



History and exam

Key diagnostic factors

  • at-risk demographic
  • family history of SCID, infant death, or consanguinity
  • recurrent and unusually severe infections
  • chronic diarrhea
  • failure to thrive
  • absent lymphoid tissue

Other diagnostic factors

  • rash
  • oral or genital ulcers
  • microcephaly
  • skeletal abnormalities
  • blindness
  • dystonia
  • radiation sensitivity

Risk factors

  • Family history of SCID
  • Family history of infant death
  • Athabascan-speaking Native American people
  • Consanguinity 

Diagnostic investigations

1st investigations to order

  • CBC
  • flow cytometry
  • chest x-ray
  • quantitative immunoglobulin test (IgG, IgM, and IgA)

Investigations to consider

  • T-cell proliferation studies
  • enzyme testing
  • serum uric acid
  • MRI chest
  • chest ultrasound
  • CT scan of the chest
  • genetic testing
  • radiation sensitivity of fibroblast cultures
  • polymerase chain reaction-based viremia testing
  • fundoscopy

Treatment algorithm


Associate Professor

Pediatrics, Allergy, and Immunology

Baylor College of Medicine

Texas Children’s Hospital




JC declares that he has no competing interests.

Dr Chinen would like to gratefully acknowledge Dr John M. Cunningham, Dr James L. LaBelle, Dr John Routes, Dr James Verbsky, Dr Nicole Chase, and Dr Ebrahim Shakir, the previous contributors to this topic. JLL, JR, JV, and NC are authors of references cited in this topic. JMC and ES declare that they have no competing interests.

Peer reviewersVIEW ALL

Professor of Pediatrics

University of Pennsylvania


Division of Allergy and Immunology

Children's Hospital of Philadelphia




KS declares that she has no competing interests.

Professor of Medicine


Adult Immunodeficiency Program

University of Colorado Denver




CK is an author of a reference cited in this topic. CK has received speaker fees from Cention, Aventis Behring, and Bristol Myers Squibb. CK has received honorarium for speaking at the Aspen Allergy Conference, for the Colorado Allergy Society. CK ran the research program for a biotechnology company with an approximate budget of $3.5 million.

Senior Lecturer

Institute of Child Health

Consultant in Paediatric Immunology & Bone Marrow Transplantation

Great Ormond Street Hospital




WQ declares that he has no competing interests.

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