Pathophysiology
1) X-linked immunodeficiency syndrome with hallmarks of eczema, recurrent infections, and thrombocytopenia with subsequent hemorrhages 2) initial presentation is usually otitis media and petechiae 3) highly vulnerable to encapsulated organisms (Strep pneumonia) and H. influenza and CMV
Characteristic Test Findings
Laboratory – 1) platelets < 30,000/microliter and abnormally small 2) serum IgM reduced 50% 3) impaired CD43 glycoprotein expression on lymphocytes 4) low or absent isohemagglutins 5) increased IgE 6) total T cell count is normal
Biochemistry
1) impaired cellular and humoral immunity 2) cannot produce antibodies against an entire antigen class of polysaccharides 3) loss of gene for Wiskott-Aldrich syndrome protein (WASP) causes disturbance in actin in the cytoskeleton 4) delayed cutaneous hypersensitivity 5) cannot produce virus-specific cytotoxic T cells
Inheritance/Epidemiology
1) caused by defective gene on Xp11.22-11.23 (numerous specific mutations) 2) affected gene codes for WASP, which is a Rho-type GTPase 3) X-linked inheritance disease that affects boys and usually presents in first weeks of life 4) death usually occurs in childhood if no bone marrow transplantation
Treatment
1) myeloablative therapy followed by bone marrow transplantation 2) IV immunoglobulin and splenectomy to palliate
Tips for USMLE
1) only disorder with smaller than normal platelets 2) one of the only disorders with impaired CD43 glycoprotein expression 3) classic triad – eczema, recurrent infections, and thrombocytopenia 4) increased lymphoreticular malignancy
Leave a Reply