X-linked hyper-IgM syndrome with eosinophilia in a male child: A case report.

The hyper-IgM syndromes (HIGMs) are a group of primary immune deficiency diseases characterized by a normal or elevated serum level of IgM and low or absent serum levels of IgG, IgA and IgE. Here, we report a case of X-linked HIGM with a new CD40L gene mutation presenting with eosinophilia. The patient experienced recurrent pneumonia and acute respiratory distress syndrome (ARDS) from 4 months of age. Immunological evaluation revealed a normal level of serum IgM, with significantly low levels of serum IgG and IgA. Genetic analysis of the CD40L gene revealed a splice mutation in exon 5 at the nucleotide position 410 (c.410-2A>G), which has never been reported previously in the literature. Following treatment with regular intravenous immunoglobulin (IVIG) replacement therapy every 3 to 4 weeks and infection prophylaxis with trimethoprim-sulfamethoxazole during follow-up, the patient's immunoglobulin level returned to normal with no pulmonary infection. The eosinophil count also returned to normal after a small dose of steroid agent treatment was administered orally for 5 months. In summary, X-linked hyper-IgM syndrome with CD40L gene mutation presenting with eosinophilia may be successfully treated using IVIG replacement therapy and a small dose of steroid agent.