combined immunodeficiency, X-linked

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combined immunodeficiency, X-linked

A form of combined immunodeficiency (OMIM:312863) caused by a mutation in the same gene (IL2RG) as that causing severe combined immunodeficiency (SCIDX), a genetically and clinically heterogeneous group of rare congenital disorders characterised by impairment of both humoral and cell-mediated immunity, leukopaenia and low or absent antibody levels. XCID is more banal, and survival up to age 30 has been described.

Clinical findings
Paucity of lymphoid tissue; recurrent sinusitis, otitis media, bronchitis, and pneumonia; severe varicella; chronic HPV infections.

Immunologic analysis
Normal concentrations of serum immunoglobulins, but reduced IgG antibody response to antigens; normal numbers of B cells and NK cells, but decreased numbers of CD4+ and CD8+ T cells; diminished proliferative responses of blood T cells to allogeneic cells, mitogens and antigens; decreased production of IL2 by mitogen-stimulated lymphocytes.

Molecular pathology
Defects in IL2RG, which encodes the gamma chain, an important signalling component of many IL receptors (e.g., IL2, IL4, IL7 and IL21), cause XCID.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.
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