The purpose of this family based natural history protocol is to allow for patients, and relatives of patients to be screened for Autoimmune Lymphoproliferative Syndrome (ALPS) and related disorders of apoptosis, RAS associated leukoproliferative disorder (RALD). Patients and relatives will be evaluated at the NIH Clinical Center if they meet the eligibility criteria. This evaluation will include blood and relevant tissue studies along with long-term clinical evaluation to define the biology, inheritance, clinical spectrum, and natural history of this syndrome. The aim of the research studies is to elucidate mechanisms underlying the immune dysregulation due to defective apoptosis in these patients. Knowledge gained from these studies provides important insights into the mechanisms of autoimmunity, normal thymic and extra thymic T cell differentiation, TCR repertoire selection, and lymphomagenesis. Medically indicated management of ALPS-related autoimmune disease and cytopenias will also be considered and provided, using standard of care treatments.