Autoimmune lymphoproliferative syndrome (ALPS), characterized by chronic lymphoproliferation, autoimmune manifestations, and an increased lymphoma risk, stems from defects in lymphocyte apoptosis, particularly in components of the apoptotic pathway (e.g., FAS, FASL, FADD, CASP10, and CASP8). The gene discussed is CASP8; the disease is autoimmune lymphoproliferative syndrome.