A 3-year-old boy has severe eczema, recurrent staphylococcal skin abscesses, and elevated serum IgE >2000 IU/mL. He has coarse facial features with a broad nasal bridge and prominent forehead. Which gene mutation is most likely responsible?

• A BTK gene on Xq22
• B CD40 ligand gene on Xq26
• C NADPH oxidase component (CYBB gene)
• D STAT3 gene on chromosome 17q21 ✓

Explanation

This describes Hyper-IgE syndrome (Job syndrome), caused by autosomal dominant STAT3 mutations. The triad includes recurrent staphylococcal abscesses, eczema, and very high IgE, plus characteristic coarse facies and skeletal abnormalities. BTK mutation causes X-linked agammaglobulinemia with low all immunoglobulins. CYBB mutation causes chronic granulomatous disease. CD40 ligand deficiency causes Hyper-IgM syndrome with normal or high IgE but different infection pattern.

Reference: Nelson Textbook of Pediatrics, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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