Combined Immunodeficiency

Combined immunodeficiency (CID) combines humoral and cellular immune defects; the severe form is severe combined immunodeficiency (SCID). Etiologies: IL2RG common-gamma-chain (X-linked), ADA deficiency, PNP deficiency, MHC class II deficiency, reticular dysgenesis, Omenn syndrome. It presents in infancy with severe recurrent infection (opportunistic: Pneumocystis, candidiasis, CMV), failure to thrive, chronic diarrhea, oral thrush, graft-versus-host from maternal engraftment. Without treatment it is fatal in infancy; curable by hematopoietic-stem-cell transplant/gene therapy.

Common Symptoms

Severe recurrent infection; oral thrush; chronic diarrhea; failure to thrive; Pneumocystis pneumonia; opportunistic infection; graft-versus-host rash

Causes and Pathogenesis

Genetic defects in T-cell development (gamma-chain, ADA, RAG, MHC) cause T-cell lymphopenia with secondary B-cell dysfunction; both cellular and humoral immunity fail.

Treatment

Hematopoietic-stem-cell transplant; gene therapy; IVIG; PCP/antifungal prophylaxis; ADA enzyme replacement; isolation

Preventive Measures

Newborn screening for SCID; avoid live vaccines; genetic counseling; irradiated/CMV-negative blood products.

Department to Visit

It is recommended to visit the Pediatric Immunology department; an appointment can be booked on this platform before the visit.

Warm reminder: The above information is for health science reference only and cannot replace professional medical diagnosis. If you have related symptoms, please seek medical attention at a regular hospital promptly.