A novel variant in the neutrophil cytosolic factor 2 (NCF2) gene results in severe disseminated BCG infectious disease: A clinical report and literature review

Background Chronic granulomatous disease (CGD) is a rare primary immunodeficiency disorder (PID) affecting NADPH oxidase activity. The rarest form of the disease is considered to be caused by NCF2 gene bi-allelic variant. Here, we report the clinical and molecular characterization of a patient presenting with early-onset severe disease due to bi-allelic NCF2 variant. Methods Gene mutational analysis was performed by whole-exome and Sanger sequencing. Results The patient presented with a history of fever and rash since the age of 1 month, followed by destructive osteomyelitis and necrotizing lymphadenopathy. The patient received the Bacillus Calmette-Guerin (BCG) vaccine at birth; she was subsequently diagnosed with disseminated BCG infection. Whole-exome sequencing identified a private (unreported) homozygous variant in NCF2 (c.290C > A) that results in a nonconservative change, p.Ala97Asp, in the p67(phox) protein. The variant is located in the third helix of the TRP domain, which is crucial for the binding of GTPase RAC2 to the NADPH oxidase complex. Conclusion We identified a novel NCF2 variant located in the region interacting with RAC2 that is linked to a severe and early CGD phenotype in the setting of disseminated BCG infection. Our findings support postponing BCG vaccination until 6-12 months of age and after PID assessment.