Primary immunodeficiency diseases (PI) are a group of more than 450 rare, chronic disorders in which part of the body’s immune system is missing or functions improperly. These diseases are caused by hereditary or genetic defects, and although some disorders present at birth or in early childhood, the disorders can affect anyone, regardless of age or gender. Some affect a single part of the immune system, others may affect one or more components of the system. While the diseases may differ, they all share one common feature: each results from a defect in one of the functions of the body’s normal immune system.
For people living with PI, infections may not go away or can come back often, even with the use of medications. Infections may be common, severe, long-lasting, hard to cure and may become life threatening.