Immunodeficiencies affecting cellular and humoral immunity

Combined immunodeficiencies (CIDs) are the result of defective development or function of T cells. As the most severe form of primary immunodeficiency disorders (PID), CIDs are characterized by a susceptibility to infection, particularly from opportunistic organisms, which leads to severe morbidity and mortality. A subpopulation of patients has additional syndromic features caused by the function of the affected gene beyond the immune system. In this chapter, we will focus on nonsyndromic CIDs.