NCF4 (Neutrophil Cytosolic Factor 4): NCF4 is a gene that encodes a component of the NADPH oxidase complex, which plays a key role in immune defense against pathogens. It helps generate reactive oxygen species in phagocytes, essential for killing microbes. Mutations in NCF4 have been linked to chronic granulomatous disease, a condition marked by recurrent bacterial and fungal infections.