CYBB and chronic granulomatous disease: Another known PID is chronic granulomatous disease (CGD), which results from defects in genes encoding the NADPH oxidase subunits (CYBA and CYBB, encoding the cytochrome B-245 alpha and beta chains, respectively; and NCF-1, NCF-2, and NCF-4, encoding neutrophil cytosolic factors 1, 2 and 4), which together are critical for the generation of superoxide within phagocytes [39].