Chronic granulomatous disease (CGD) is a primary immunodeficiency characterized by increased susceptibility to bacteria and fungi since early in life, caused by mutations in any of the five genes coding for protein subunits in NADPH oxidase. X-linked variant CGD can be missed during routine evaluation or present later in life due to hypomorphic mutations and a residual superoxide production. The case of a 10-month-old boy who died of pneumonia is reported. The isolation of Burkholderia cepacia from his lung, together with a marginally low nitroblue tetrazolium reduction assay (NBT), made us suspect and pursue the molecular diagnosis of CGD. A postmortem genetic analysis finally demonstrated CGD caused by a hypomorphic missense mutation with normal gp91phox expression. In a patient being investigated for unusually severe or recurrent infection, a high index of suspicion of immunodeficiency must be maintained. 1. Introduction Chronic granulomatous disease (CGD) is a rare primary immunodeficiency that affects microbial killing by phagocytes, resulting in bacterial, fungal, and/or mycobacterial infections since early life [1, 2]. The superoxide production by NADPH oxidase is markedly reduced or absent due to mutations in any of the five genes coding for protein subunits of the enzymatic complex [3]. Mutations in CYBB, coding for gp91phox, result in the most common X-linked CGD (65%–70% of all cases) [4]. Hypomorphic mutations (Xgp91+ and Xgp91-) may result in X-linked variant CGD [5, 6]. Patients with variant CGD express the gp91phox protein and produce decreased but detectable superoxide, which allow the defect to manifest later in life with a milder history of infections. By far, the most common micro-organisms causing infections in CGD are Staphylococcus aureus and Aspergillus species; other agents include Pseudomonas, Serratia, Salmonella, and Candida species. Burkholderia cepacia infection is frequently associated to CGD diagnosis (6–8). Here, we present the case of a patient who died of Burkholderia cepacia lung infection, in whom the diagnosis of X-CGD could only be attained postmortem due to residual superoxide production and normal protein expression. 2. Case Report A 10-month-old boy, the first child of nonconsanguineous parents living in the Tahiti archipelago (French Polynesia), was referred for severe pneumonia. The father is from Europe and the mother is from Oceania; there was no relevant family history. During the first months of life, the patient had experienced some infections, mostly of the upper airways, as well as bronchitis and
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