Tehran University of Medical Sciences Immunology and Genetics Journal 2645-4831 2 4 2019 12 01 207 212 Arezou Rezaei Research Center for Immunodeficiencies, Pediatrics Center of Excellence, Childrens Medical Center, Tehran University of Medical Science, Tehran, Iran Paniz Shirmast Research Center for Immunodeficiencies, Pediatrics Center of Excellence, Childrens Medical Center, Tehran University of Medical Science, Tehran, Iran Mohammad Hossein Eslamian Allergy and clinical immunology division, Department of pediatrics, Hamadan University of medical science, Hamadan, Iran. 2019 10 19 NF-κB pathway is a complex protein playing an important role in regulating lymphocyte development, immune responses, inflammation, cell proliferation, and cell death. The NF-kB signaling pathway has been described to be associated with canonical and noncanonical pathway. The canonical pathway utilizes NF-kB1, whereas the latter pathway involves NF-kB2, which is the cornerstone of the non-canonical NF-kB pathway, and has been shown to be critical for the development of secondary lymphoid organs, B cell development, and the humoral response to T-dependent and T-independent antigens. In this study, we investigated the patient with chief complain of low body temperature as well as feeling cold even in the warm seasons since 15 years ago. We reported a middle age man with mild lymphopenia and no significant infection, but hypothermia with significant chills even in the warm seasons with a mutation in NF-κB2 pathway. https://igj.tums.ac.ir/index.php/igj/article/view/39 https://igj.tums.ac.ir/index.php/igj/article/download/39/30