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

Abstract

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‐Guérin (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 p67phox 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.

Clinical and molecular significance of flow cytometric analysis for reactive oxygen species production and residual p67phox expression in p67phox‐deficient chronic granulomatous disease

“…13,14 The results are presented as the stimulation index (SI), which is the ratio of the mean fluorescence intensity (MFI) of stimulated granulocytes to unstimulated granulocytes. [10][11][12]15,16 We always evaluated healthy individuals as positive controls and confirmed that the consistent results were obtained.…”

“…After erythrocyte lysis, the production of ROS by granulocytes was quantified by measuring intracellular rhodamine with FACSCalibur flow cytometer (BD Bioscience, Tokyo, Japan), as previously described 13,14 . The results are presented as the stimulation index (SI), which is the ratio of the mean fluorescence intensity (MFI) of stimulated granulocytes to unstimulated granulocytes 10–12,15,16 . We always evaluated healthy individuals as positive controls and confirmed that the consistent results were obtained.…”

“…Mutational hotspots are distributed along the length of the NCF2 gene 5 ; however, one of these mutations, Arg102X, was identified in 5 of 11 patients (allele frequency of 27% [6/22]). Arg102X has previously been reported as the nearly complete lack of DHR activity and protein expression levels in p67 phox ‐CGD 5,12,16,22 . By contrast, the missense variant, Tyr394Asp, can be relatively functional with diminished DHR activity and p67 phox expression 5,23 .…”

“…Arg102X has previously been reported as the nearly complete lack of DHR activity and protein expression levels in p67 phox -CGD. 5,12,16,22 By contrast, the missense variant, Tyr394Asp, can be relatively functional with diminished DHR activity and p67 phox expression. 5,23 Our flow cytometric analysis results with Patients #3, #8, and #11 were virtually consistent with the preceding analysis, which suggested that our results were reasonable.…”