Focus on FOCIS: the continuing diagnostic challenge of autosomal recessive chronic granulomatous disease

Chronic granulomatous disease (CGD) is a primary immunodeficiency of defective neutrophil oxidative burst activity due to mutations in the genes CYBA, NCF-1, NCF-2, and CYBB, which respectively encode the p22-phox, p47-phox, p67-phox, and gp91-phox subunits. CGD usually presents in early childhood with recurrent or severe infection with catalase-positive bacteria and fungi. We present an unusual case of CGD in which Burkholderia cepacia lymphadenitis developed in a previously healthy 10-year-old girl. Flow cytometric analysis of dihydrorhodamine (DHR)-labeled neutrophils performed by a CLIA-approved outside reference laboratory was reported as normal. However, we found that this patient's neutrophil oxidative burst activity in DHR assays was substantially reduced but not absent. A selective decrease in intracellular staining for p67-phox suggested the diagnosis of autosomal recessive CGD due to NCF-2 gene mutations, and a novel homozygous and hypomorphic NCF-2 gene mutation was found. The potential mechanisms for this delayed and mild presentation of CGD are discussed.