Chronic granulomatous disease (CGD) is a congenital IEI that presents with recurrent fungal and bacterial infection characterized by the formation of multiple systemic granulomas, which are common features of the disease. It is caused by defects in one of the subunits of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase system, resulting in the failure of the oxidative killing of catalase-positive organisms despite normal phagocytosis [2]. The gene discussed is CAT; the disease is chronic granulomatous disease.