Misclassification of Ataxia Telangiectasia with Hyper IgM immune profile

Document Type: Case Report


1 Department of Allergy and Clinical Immunology, Department of Pediatrics, Pediatrics Center of Excellence, Children's Medical Center, Tehran, University of Medical Sciences, Tehran, Iran

2 Pediatric Rheumatology Research Group, Rheumatology Research Center, Tehran University of Medical Science, Tehran, Iran

3 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.