CYBA and chronic granulomatous disease: CGD is a genetically heterogeneous disease caused by a defect in any of the five structural components of the nicotinamide adenine dinucleotide phosphate (NAPDH) oxidase complex including the granule or plasma membrane-bound glycoproteins gp91phox (phagocyte oxidase) and p22phox, and the cytoplasmatic components p47phox, p67phox and p40phox [4].