Tehran University of Medical Sciences Immunology and Genetics Journal 2645-4831 3 1 2020 03 01 29 40 Tannaz Moeini Shad Research Center for Immunodeficiencies, Pediatrics Center of Excellence, Children's Medical Center, Tehran University of Medical Science, Tehran, Iran Mohammad Reza Ranjouri Research Center for Immunodeficiencies, Pediatrics Center of Excellence, Children's Medical Center, Tehran University of Medical Science, Tehran, Iran Parisa Amirifar Research Center for Immunodeficiencies, Pediatrics Center of Excellence, Children's Medical Center, Tehran University of Medical Science, Tehran, Iran 2020 01 19 Background/objectives: AT is an autosomal recessive primary immunodeficiency (PID) disease with multisystem involvement caused by biallelic mutations in the ataxia telangiectasia mutated (ATM) gene. The patients with AT represent a broad range of clinical manifestations including progressive cerebellar ataxia, oculocutaneous telangiectasia, immunodeficiency, and susceptibility to malignancies. We aimed to determine different clinical features of the AT patients to identify their key diagnostic or prognostic characteristics. Methods: In the present study, 120 patients with the confirmed diagnosis of AT were enrolled from Iranian immunodeficiency registry center. A demographic information, clinical complications, and laboratory data were obtained from all the patients to evaluate the clinical manifestations. Results: In this study, we found that in the AT patients, the frequency of total infection, respiratory infection, gastrointestinal infection, urinary tract infection, chronic fever, lymphadenopathy, and hepatosplenomegaly were 83.3%, 68.3%, 18%, 6.7%, 26.7%, 7.5%, and 20%, respectively. Conclusion: The AT patients present different types of infections and noninfectious complications; therefore, early detection and careful management is necessary for these patients. https://igj.tums.ac.ir/index.php/igj/article/view/43 https://igj.tums.ac.ir/index.php/igj/article/download/43/33