Medical MCQ - A 10-year-old boy with a history of recurrent bacterial infections presents with fever and a productive cough. Biochemical analysis of his neutrophils demonstrates defective oxidative burst. This patient most likely has inherited mutations in the gene that encodes which of the following proteins?

A 10-year-old boy with a history of recurrent bacterial infections presents with fever and a productive cough. Biochemical analysis of his neutrophils demonstrates defective oxidative burst. This patient most likely has inherited mutations in the gene that encodes which of the following proteins?

Catalase

Cytochrome P450

Myeloperoxidase

NADPH oxidase

Question Category:

Pathology

Correct Answer:

NADPH oxidase

Description:

The impoance of oxygen-dependent mechanisms in the bacterial killing by phagocytic cells is exemplified in chronic granulomatous disease (CGD). Children with this disease suffer from a hereditary deficiency of NADPH oxidase which leads to decreased oxidative burst. Susceptible to recurrent bacterial infections. The most common variants are an X-linked defect in one of the membrane-bound components (gp91phox) and autosomal recessive defects in the genes encoding two of the cytoplasmic components (p47phox and p67phox). -Patients deficient in myeloperoxidase (choice C) cannot produce hypochlorous acid (HOCl) and experience an increased susceptibility to infections with the fungal pathogen Candida. -Catalase (choice A) conves hydrogen peroxide to water and molecular oxygen. Diagnosis: Chronic granulomatous disease

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