A 4-year-old boy is evaluated for recurrent respiratory infections, eczema, and petechiae. Laboratory studies show thrombocytopenia, decreased IgM levels, with increased IgA and IgE. What is the most probable diagnosis?

- The presentation of a young boy with recurrent respiratory infections, eczema, and petechiae along with thrombocytopenia and an immunoglobulin pattern of decreased IgM and increased IgA and IgE is characteristic of Wiskott-Aldrich syndrome.
- This X-linked immunodeficiency results from defects in the WAS gene, leading to abnormal platelet formation (causing thrombocytopenia with small platelets) and impaired T-cell function causing susceptibility to infections.
- The altered immunoglobulin profile with low IgM and elevated IgA and IgE further supports this diagnosis.
- The triad of eczema, thrombocytopenia, and recurrent infections is pathognomonic of this syndrome.

Reference: Davidson’s Principles and Practice of Medicine, 24th Edition, Chapter: Immunodeficiency, Page 506.