The Immune Deficiency Foundation (IDF), founded in 1980, is the national nonprofit organization dedicated to improving the diagnosis, treatment and quality of life of persons with primary immunodeficiency diseases through advocacy, education and research. Primary immunodeficiency diseases (PI) are a group of more than 350 rare, chronic disorders in which part of the body's immune system is missing or functions improperly. Because one of the most important functions of the normal immune system is to protect us against infection, patients with PI commonly have an increased vulnerability to infections, which can be recurrent, unusually severe, or won't clear up. People with PI can face frequent health problems and often develop serious and debilitating illnesses. There are approximately 250,000 people who are diagnosed with PI in the U.S., and thousands more go undetected. With early diagnosis and appropriate therapies, many patients diagnosed with a PI can live healthy, productive lives.