Chronic granulomatous disease (CGD) is a rare primary immunodeficiency caused by a dysfunction of the NADPH oxidase enzyme, especially in neutrophils (PNN). This defect leads to insufficient production of reactive oxygen species (ROS), which are essential for eliminating intracellular pathogens, thereby predisposing patients to recurrent and severe infections. The dihydrorhodamine (DHR) flow cytometry assay is a functional test used to evaluate neutrophil oxidative activity. This study aims to identify CGD cases in children with recurrent infections and screen carrier females using the DHR test.
This was a retrospective descriptive study conducted over 24 months in the immunology laboratory at Ibn Rochd University Hospital in Casablanca. Included were patients who underwent the DHR test, while uninterpretable results and incomplete records were excluded. Flow cytometry using DHR with PMA stimulation was used to measure DHR oxidation into fluorescent rhodamine. Data were collected from the laboratory information system and medical records.
The study included 171 patients (58.48% male, 41.52% female), with an average age of 4 years in children and 30.8 years in adults. Most cases came from pediatric departments (161 patients). The main indications were abscesses (32.52%) and recurrent infections (22.76%). The DHR test showed normal neutrophil responses in 135 patients (93.69% PMA response), decreased response in 23 patients (65.76%), and absent response in 13 patients (0.27%). CGD was genetically confirmed in all children with absent oxidative response and in 23.8% of children with a partial response. Two women were identified as X-linked carriers based on the bimodal histogram patterns.
The high proportion of children (94.15%) in this study is consistent with the literature, where 80–90% of CGD cases are diagnosed before the age of five. The DHR test is a rapid and sensitive tool for diagnosing CGD, effectively distinguishing between normal and defective responses. In our series, CGD was confirmed in 100% of children with absent DHR responses, justifying early intervention and family screening.
