The requirement of reactive oxidative species (ROS) production by NADPH oxidase to protect against invasive fungal infections is underscored by the high prevalence of Aspergillus infections in patients with chronic granulomatous disease (CGD), a rare hereditary disease, in which a defect in one of the subunits of NADPH oxidase leads to a defect in ROS production by phagocytes, resulting in severe recurrent bacterial and fungal infections (10). This evidence concerns the gene FMO5 and chronic granulomatous disease.