Document Type: Case Report
Department of Allergy and Clinical Immunology, Department of Pediatrics, Pediatrics Center of Excellence, Children's Medical Center, Tehran, University of Medical Sciences, Tehran, Iran
Pediatric Rheumatology Research Group, Rheumatology Research Center, Tehran University of Medical Science, Tehran, Iran
Department of Allergy and Clinical Immunology, Child Growth and Development Research Center, Research Institute for Primordial Prevention of Non-Communicable Disease, Isfahan University of Medical Sciences, Isfahan, Iran
Ataxia-telangiectasia is a rare primary immunodeficiency and multisystem DNA repair disorder which is caused by mutation in ataxia telangiectasia mutated (ATM) gene. The ATM protein plays a critical role in sensing DNA double-strand breaks (DSB), oxidative stress and other genetic stresses. The ATM can directly mention DNA ends in repair complexes and directly involved in the repair of DSBs induced during T cell and B cell rearrangement. Therefore, increase serum IgM level and recurrent infection mainly sinopulmonary, indistinguishable from hyper IgM syndrome can be a presentation of some AT patients. AT patients with class-switched defect are more prone to severe infections, autoimmunity and lymphoproliferative disorders. Herein we present an AT patient with characteristic feature of hyper IgM phenotype and lymphoproliferation.