Background: Chronic granulomatous disease (CGD) is a rare immune disorder caused by a mutation in the CYBB gene. People with CGD have white blood cells that do not work properly. This places them at risk of developing infections that may be life-threatening. Stem cell transplant can cure CGD but transplanting stem cells donated by other people can have serious complications. In addition, not everyone has a matched donor. Another approach is a type of gene therapy that involves base-editing to correct the mutation in a person s own stem cells. Researchers want to know if the base-edited stem cells can improve the white cells' functioning and result in fewer CGD-related infections. Objective: To learn if base-edited stem cells will improve white blood cells' ability to fight against infections in people with CGD. Eligibility: Males aged 18 years and older with X-linked CGD. Design: This is a non-randomized study. Participants with the specific mutation under study will be screened during the initial phase. During the development phase, participants will undergo apheresis to collect stem cells for base-editing correction of the mutation. During the treatment phase, participants will receive the base-edited cells after chemotherapy with busulfan. Participants will remain in the hospital until their immunity recovers. Follow-up visits will continue for 15 years.