Chronic granulomatous disease (CGD) is a rare immunodeficiency disorder characterized by a defective NADPH oxidase complex leading to an impaired respiratory burst and defective killing of pathogens by phagocytes. The most common type of CGD is caused by hemizygous mutations of the CYBB gene on the X chromosome encoding the gp91phox subunit. It usually affects males, yet heterozygous females may rarely manifest clinical signs of the disease due to skewed X chromosome inactivation in leukocytes . Despite advances in gene therapy, hematopoietic stem cell transplantation (HSCT) remains the main definitive treatment. Older patients, however, are at greater risk of HSCT-related complications and mortality and may require a specific approach.
