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Wiskott-Aldrich syndrome results from a combined B- and T-cell defect and is characterized by recurrent infection, eczema, and thrombocytopenia.
Inheritance is X-linked recessive. Wiskott-Aldrich syndrome is caused by mutations in the gene that encodes the Wiskott-Aldrich syndrome protein (WASP), a cytoplasmic protein necessary for normal B- and T-cell signaling. Because B- and T-cell functions are impaired, infections with pyogenic bacteria and opportunistic organisms, particularly viruses and Pneumocystis jirovecii, develop. Infections with varicella zoster virus and herpesvirus are common.
The first manifestations are often hemorrhagic (usually bloody diarrhea), followed by recurrent respiratory infections, eczema, and thrombocytopenia. Cancers, especially Epstein-Barr virus lymphomas and acute lymphoblastic leukemia, develop in about 10% of patients > 10 yr.
Diagnosis is based on a decreased T-cell count and function, elevated IgE and IgA levels, low IgM levels, and low or normal IgG levels, decreased natural killer cell cytotoxicity, and impaired neutrophil chemotaxis. Antibodies to polysaccharide antigens (eg, blood group antigens A and B) may be selectively deficient. Platelets are small and defective, and splenic destruction of platelets is increased, causing thrombocytopenia. Mutation analysis may be used to confirm the diagnosis. Genetic testing is recommended for 1st-degree relatives.
Because risk of lymphoma and leukemia is increased, a CBC with differential is usually done every 6 mo. Acute changes in symptoms related to B-cell dysfunction require more in-depth evaluations.
Treatment is prophylactic antibiotics and IV immune globulin to prevent recurrent bacterial infections, acyclovir to prevent severe herpes simplex virus infections, and platelet transfusions to treat hemorrhage. If thrombocytopenia is severe, splenectomy can be done, but it is usually avoided because it increases risk of septicemia.
The only established cure is bone marrow transplantation, but gene therapy is under study.
Without transplantation, most patients die by age 15; however, some patients survive into adulthood.
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