Introduction
Activation induced cytidine deaminase (AID) is an essential enzyme for class switch recombinationand somatic hypermutation. We herein report a patient who had AID gene defect and is diagnosed as the autosomal recessive form of hyper-IgM syndrome (HIGM) type 2.
Case report
A 8-year-old male patient was referred to our hospital for further evaluation of low immunoglobulin levels. The patient was the second child of the family with neither family history of immunodeficiency nor serious infections/hospitalizations up to 3 years of age. Parents were non-consanguineous and healthy. In the third year of life he had begun to suffer from recurrent otitis media and papular skin lesions. Physical examination on admission showed enlarged (1.5x1.5cm) cervical lymph nodes. Laboratory tests revealed hemoglobin levels of 13.7 g/dL, a white blood cell count of 10500/mm3, platelet count of 255000/mm3, there was not any abnormal findings in liver and renal function tests. He had high IgM, while he had low IgA, IgE and IgG (IgM 261 mg/dL, IgA <7 mg/dL, IgE <1,00 UI/mL, and IgG <33,3 mg/dL). Lymphocyte subsets, CH50, C3, and C4 levels, NBT were normal. Based on clinical/laboratory findings, the initial diagnosis was HIGM sydrome and intravenous immunoglobulin (IVIG) replacement therapy (0.4 g/kg) was started monthly. In the follow-up, we performed “next generation sequencing (NGS)” analysis for primary immunodeficiency diseases, anda homozygous c.70C>T (p.R24W) mutation was found in AID gene.
Conclusion
HIGM2 should be considered in patients presenting with recurrent infections. Early diagnosis and treatment will decrease the risks of complication.