FMO5 and chronic granulomatous disease: Flow cytometry showed diminished gp91phox expression in the patient's neutrophils suggestive of X-linked CGD.<h4>Conclusion</h4>Our case highlights that early-onset inflammatory bowel disease can be a presenting manifestation of CGD and diagnosis of CGD can be missed if NBT alone is used for screening, especially in the presence of NADPH oxidase activity.