The purposes of this study are to 1) identify the genes responsible for certain immune disorders, 2) learn about the medical problems they cause, and 3) learn how to predict who is likely to develop these disorders and what the risk is of passing them on to children. The immune system is the body s defense system. Some immune deficiencies impair a person s ability to fight infections; others render a person susceptible to allergies, or to autoimmune diseases such as lupus or arthritis, in which the immune cells (white blood cells) attack and destroy the body s own tissues.