Defect of NADPH oxidase → ↓ reactive oxygen species (eg, superoxide) and ↓ respiratory burst in neutrophils.

- X-linked form most common

- ↑ susceptibility to catalase ⊕ organisms (Nocardia, Pseudomonas, Listeria, Aspergillus, Candida, E coli, Staphylococci, Serratia)

Findings:- Abnormal dihydrorhodamine (flow cytometry) test (↓ green fluorescence)- Nitroblue tetrazolium dye reduction test fails to turn blue