Primary immunodeficiency diseases

Abstract Primary immunodeficiency diseases (PID), or inborn errors of immunity, are a heterogeneous and variable group of disorders that result in increased susceptibility to infectious diseases, as well as the development of autoimmune disease, lymphoproliferation, and dysregulated inflammation. Often presenting in childhood, many of these diseases cause significant morbidity and can be fatal if not identified. This chapter aims to summarize laboratory evaluation of suspected PID cases, as well as a description of some of the most commonly observed disorders.