Editors: Seyed Alireza Mahdaviani, Nima Rezaei

2019

Primary immunodeficiency diseases (PIDs) are a heterogeneous group of disorders, characterized by increased susceptibility of infections, mainly in respiratory system. More than 350 different PIDs have already been recognized and classified into 8 groups. Many patients with PIDs firstly present with upper and lower respiratory tract manifestations, while delay in diagnosis can lead to morbidity and even mortality of affected patients.