Tehran University of Medical Sciences Immunology and Genetics Journal 2645-4831 3 3 2020 09 01 8 15 Nazanin Aghamohamadi Department of Immunology, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran Ali Zarezadeh Mehrabadi Department of Immunology, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran 2020 07 13 Activated PI3 kinase delta syndrome (APDS) is a newly recognized primary immunodeficiency that was firstly discovered in 2013. APDS can result from gain-of-function mutations in PI3Kδ catalytic p110δ (PIK3CD known as APDS1) and regulatory p85α (PIK3R1 known as APDS2). Patients with APDS syndrome mostly present some major manifestations such as lymphadenopathy and autoimmune diseases like cytopenia and Immune thrombocytopenic purpura (ITP). Distinguishing APDS from the other antibody deficiencies such as the common variable immunodeficiency (CVID) and hyper IgM disorders is very important to use appropriate and targeted treatment strategies. In this review article, we attempted to discuss the pathogenesis, cell abnormality, clinical manifestations, diagnosis, and treatment of APDS disorder. https://igj.tums.ac.ir/index.php/igj/article/view/52 https://igj.tums.ac.ir/index.php/igj/article/download/52/43