An IRF2BP2 Variant in a Pediatric Patient with Common Variable Immunodeficiency.

Background: Interferon regulatory factor-2 binding protein 2 (IRF2BP2) is an important new transcriptional cofactor that interacts with IFN regulatory factor 2 (IRF-2) and an IRF-2-dependent transcriptional repressor. IRF2BP2 plays a role in different cellular functions, including apoptosis, survival, and cell differentiation. In this study, we report a case with common variable immunodeficiency (CVID), which has a heterozygous variant in the IRF2BP2 gene. Case Presentation: A 13-year-old girl was evaluated for immunodeficiency due to recurrent sinusitis and tonsillitis in the previous year. She had been suffering from chronic cough for 3 months. She was hospitalized with lobar pneumonia and bronchiectasis. She was the second child of consanguineous parents. On physical examination, there was no growth and development retardation. Immunological screening of the patient demonstrated panhypogammaglobulinemia with low total memory B and class-switching memory B cells. Specific antibody responses to rubella and hepatitis B were negative. T- and B-lymphocyte counts and T-cell responses to phytohemagglutinin (PHA) were normal. Exome sequencing identified a heterozygous variant in IRF2BP2 (c.112C>Tp.Arg38Cys). On follow-up, she has maintained a good infection control with antibiotic prophylaxis and immunoglobulin replacement therapy. Conclusion: To the best of our knowledge, this case is the youngest CVID who was diagnosed with IRF2BP2 in the literature. The low percentage of total memory and switched memory B cells in the proband suggested that IRF2BP2 might have had a role in the development or survival of memory B cells. Functional studies are needed about the critical role of IRF2BP2 protein in B-cell maturation and humoral immune responses.