Severe Combined Immune Deficiency (XSCID), X-linked

X-Linked Severe Combined Immunodeficiency (XSCID) is a severe combined immunodeficiency disorder that typically has a lymphocyte profile of T?, B+, NK?, with a prevalence of about 1 in 50,000 to 1 in 100,000 live births. XSCID usually manifests in affected males between three and six months of age. The clinical presentation during the first year of life almost universally includes failure to thrive, oral/diaper candidiasis, recurrent infections, absent tonsils and lymph nodes, persistent infections and infections with opportunistic organisms. Other features that may be noted are disseminating infections, recurrent bacterial meningitis and transplacental transfer of maternal lymphocytes to the infant, resulting is graft-vs-host disease with erythematous skin rashes, hepatomegaly and lymphadenopathy. Atypical XSCID occurs in a small subset of patients whose IL2RG gene produces a small amount of protein with residual activity. These individuals have an atypical presentation that is T+B+NK?. These patients may display immune disregulation and autoimmunity presenting with rashes, splenomegaly, gastrointestinal malabsorption, other autoimmune conditions, and short stature.

Tests Available

Forms and Documents

Test Details

  • Confirmation of a clinical diagnosis
  • Molecular follow-up to abnormal result in newborn screen for T-cell receptor excision circles
  • Differentiation between X-linked and autosomal forms of SCID
  • Carrier detection in female relatives of an affected male
  • Prenatal diagnosis in at-risk pregnancies
  • Capillary Sequencing


3 weeks
2-5 mL Blood - Lavender Top Tube
Oral Rinse (30-40 mL)|Dried Blood Spots|Buccal Swabs


  • 279.2 Combined immunity deficiency
  • 279.1 Deficiency of cell-mediated immunity
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  6. GeneReviews at GeneTests: Medical Genetics Information Resource. Copyright, University of Washington, Seattle. 1993- 2010. Available at Accessed 08-2010.