RecruitingAscertainment of Families for Genetic Studies of Familial Lymphoproliferative DisordersThe purpose of this study is to better understand the genetic causes of Hodgkin's disease (a kind of lymphoma) and non-Hodgkin's lymphoma, as well as multiple myeloma, leukemia, and related diseases. The doctors have identified the patient because 1) they have had a lymphoproliferative disorder such as lymphoma, leukemia, or multiple myeloma, and have a family member with one of these disorders or 2) they are a member of a family with a lymphoproliferative disorder, including Hodgkin's disease and/or, non-Hodgkin's lymphoma or a second cancer after Hodgkin's disease.