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In an evaluation of an 8-year-old who has recurrent infections since the first year of life, findings include enlargement of the liver and spleen, lymph nod inflammation, and a superficial dematitis resembling eczema. Microscopic examination of a series of peripheral blood smears taken during a course of a staphylococcal infection indicates that the bactericidal capacity of the boy's neutrophils is impaired or absent.Which of the flowing is the most likely cause of this child's illness?
A.
Defect in the enzyme NADPH oxidase
B.
Defect in the enzyme adenosine deaminase ( ADA )
C.
Defect in the IL-2 receptor
D.
Developmental defect at the pre-B stage
E.
Developmental failure of pharyngeal pouches 3 to 4