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Key Features

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Essentials of Diagnosis
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  • Immunodeficiency with recurrent infections

  • Microplatelet thrombocytopenia

  • Eczema

  • Occurs only in males

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General Considerations
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  • Characterized by immunodeficiency, microplatelet thrombocytopenia, and eczema

  • Results from mutations of the gene encoding WAS protein (WASP) at X11p

  • WASP is a protein involved in the rearrangement of actin and is important in interactions between T lymphocytes and antigen-presenting cells

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Clinical Findings

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Symptoms and Signs
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  • Common presenting symptoms include mucosal bleeding, bloody diarrhea, cerebral hemorrhage, and severe infections with polysaccharide-encapsulated bacteria

  • Clinical presentation can vary from classic severe Wiskcott-Aldrich syndrome to mild thrombocytopenia without immunodeficiency, or X-linked thrombocytopenia, depending on the mutation

  • Malignancies and autoimmune syndromes can develop over time

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Differential Diagnosis
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  • Idiopathic thrombocytopenic purpura

  • Leukemia

  • Myelodysplasia

  • Drug adverse effect

  • Infection

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Diagnosis

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Laboratory Findings
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  • Low platelet count

  • Small platelets

  • Low or absent isohemagglutinins

  • Reduced antibody responses to polysaccharide antigens (Streptococcus pneumoniae and Haemophilus influenzae)

  • IgM may be low

  • IgG is usually normal

  • IgA and IgE are often high

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Diagnostic Procedure
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  • Diagnosis can be confirmed by genetic testing for a mutation of the WASP gene or by assessing WASP expression

  • Genetic testing can also be used for carrier screening

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Treatment

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  • Infection prophylaxis with antibiotics (including trimethoprim-sulfamethoxazole for Pneumocystis jirovecii pneumonia)

  • IVIg-replacement therapy for patients with deficient antibody responses

  • Splenectomy to reduce thrombocytopenia has been helpful in some patients with X-linked thrombocytopenia, but it must be followed by antibiotic prophylaxis because of the increased risk of septicemia and sudden death

  • Platelet transfusions should be avoided unless severe bleeding has occurred

  • Finally, bone marrow transplantation using the best-matched donor offers the possibility of a definitive cure, but it is associated with morbidity and mortality

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Outcome

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Prognosis
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  • Left untreated, survival beyond adolescence is rare

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Reference

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Kersseboom  R  et al: Educational paper: syndromic forms of primary immunodeficiency. Eur J Pediatr 2011;170:295–308
[PubMed: 21337117]

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