Case report: a case of CYBB gene variant in X-linked chronic granulomatous disease.

Chronic granulomatous disease (CGD) is an inherited immunodeficiency characterized by impaired phagocytic function due to defects in the NADPH oxidase complex. This enzymatic deficiency compromises the production of reactive oxygen species required for microbial killing, predisposing affected individuals to recurrent and often severe infections. Pulmonary involvement is particularly frequent. We describe a 10-year-old Chinese boy who initially presented with persistent fever and failed to respond adequately to standard therapy, ultimately developing rapidly progressive multi-organ failure. Genetic testing identified a hemizygous variant (c.252G > A) in exon 3 of the X-linked CYBB gene, which produces a splicing mutation(p.Ala84=). His mother was confirmed to be a heterozygous carrier. This case underscores the value of molecular diagnostics in confirming X-linked CGD (X-CGD) and highlights the importance of prenatal testing to prevent recurrence in high-risk families.