Chronic granulomatous disease, or CGD in short, is a hereditary immunodeficiency caused by mutations in genes that encode the key components of the phagocyte NADPH oxidase (known as NOX2), gp91phox, p22phox, p47phox, p67phox, and seldom p40phox, resulting in impaired formation of superoxide anion and other reactive oxygen intermediates. This evidence concerns the gene CYBB and chronic granulomatous disease.