FAS and autoimmune lymphoproliferative syndrome: Aberrant accumulation of DN T cells is also a clinical hallmark of the Autoimmune Lymphoproliferative Syndrome (ALPS, also known as Canale-Smith syndrome), a genetic disorder caused by defective FAS-mediated apoptosis that is characterized by the development of autoimmune disease, splenomegaly, lymphadenopathy, and an increased risk of secondary lymphomas during childhood (79, 80).