Abstract The dihydrorhodamine‐123 flow cytometry (DHR FC) assay is used to diagnose chronic granulomatous disease (CGD). This study presents the experience of a single center with the DHR FC assay in a large cohort to evaluate its applications and limitations. A total of 179 subjects were included in the study for CGD diagnosis, X‐linked CGD (X‐CGD) carrier determination, and post‐hematopoietic stem cell transplantation (HSCT) chimerism monitoring. We performed the DHR FC assay using a standardized protocol, with additional intracellular myeloperoxidase (MPO) staining for borderline cases. The DHR FC assay demonstrated high diagnostic accuracy. PMA stimulation detected 94% of CGD cases. E. coli stimulation identified all CGD cases, including atypical EROS‐deficient ( CYBC1 ) patients (4.3% of the cohort) who exhibited residual reactive oxygen species production (median SI PMA = 40 vs. E. coli = 24). Genetic confirmation revealed that 82% of CGD patients had X‐CGD ( CYBB ), and 18% had autosomal recessive CGD ( CYBA / NCF1 / NCF2 / CYBC1 ) forms. Borderline results were clarified by MPO staining, which diagnosed three MPO‐deficient cases. The assay reliably identified 43 X‐CGD carriers out of 45 suspected cases and showed a strong correlation with the real‐time quantitative polymerase chain reaction for HSCT chimerism monitoring ( r = 0.78, p < 0.0001). The DHR FC assay is a rapid and reliable diagnostic tool for CGD, providing results within hours. Its applications extend to X‐CGD carrier detection and post‐HSCT chimerism monitoring. Dual‐stimulant protocols (PMA + E. coli ) and MPO staining enhance diagnostic accuracy. These findings support the use of the DHR FC assay as a versatile and essential tool in CGD management.
Oiuna et al. (Mon,) studied this question.