Chediak-Higashi syndrome is characterized by recurrent pyogenic infections, partial albinism, and peripheral neuropathy. The defect lies in which specific cellular function?

• A Absent oxidative burst due to NADPH oxidase component mutation
• B Defective fusion of lysosomes with phagosomes due to LYST protein mutation causing giant granules ✓
• C Deficiency of myeloperoxidase causing impaired H2O2 utilization
• D Absent CD18 integrin preventing neutrophil extravasation (LAD-1)

Explanation

Chediak-Higashi syndrome is caused by mutations in the LYST (CHS1) gene encoding a vesicle trafficking protein. LYST deficiency impairs fusion of lysosomes with phagosomes, leading to formation of pathological giant granules visible in neutrophils and melanocytes on peripheral smear. This impairs intracellular killing. Chronic granulomatous disease results from NADPH oxidase mutation (absent oxidative burst). MPO deficiency is generally mild. LAD-1 involves CD18 deficiency.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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