A Novel Mutation in CD40LG Gene Causing X-Linked Hyper IgM Syndrome

Excerpt

To the Editor: A 4-mo-old male infant was admitted to our hospital for treatment of pneumonia. He was intubated because of the rapid progression to acute respiratory distress syndrome (ARDS). He underwent immunologic evaluation and bronchoalveolar lavage (BAL). Systemic corticosteroids and intravenous immunoglobulin were administered after the immunologic studies were performed. After treatment with these medications, he rapidly recovered from ARDS. Serum immunoglobulin (Ig) levels were as follows: IgG, 54 mg/dL (480–1200 mg/dL); IgA, below detectable limits (33–180 mg/dL); and IgM, 105 mg/dL (54–200 mg/dL). Polymerase chain reaction (PCR) for Pneumocystis jiroveci (P. jiroveci) in the BAL fluid revealed positive results. He received no specific treatment targeting the P. jiroveci infection because the P. jiroveci PCR were confirmed to be positive on the 14th day of admission. To obtain an accurate diagnosis, he underwent lung biopsy and histopathological examination demonstrated the formation of a foamy eosinophilic alveolar exudate (Fig. 1a and b). We performed whole exome sequencing (WES) and the details are described in Table 1. This variant has not been reported previously and was confirmed by Sanger sequencing. Family DNA analysis revealed that his mother was a heterozygous carrier but his father, brother, and maternal grandmother had no relevant mutations (Fig. 1c).

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