Apoptosis and Autoimmunity: Lymphoproliferative Syndromes
Autoimmune lymphoproliferative syndrome (ALPS), also known as Canale-Smith syndrome, is a genetically determined disease characterized by accumulation of lymphoid cells, hypergammaglobulinemia, and autoimmunity. It is caused by mutations in genes encoding components of the cell death pathway that is activated by the ligation of Fas, a member of the tumor necrosis factor (TNF) receptor family. Genotyping of family members of ALPS patients for Fas mutations usually reveals a dominant pattern of inheritance, but relatives that share the mutation often have no history of lymphadenopathy or autoimmune disease, even though their lymphocytes are resistant to apoptosis following ligation of Fas. This illustrates the great variation in the penetrance of the disease. Moreover, the significance of ALPS has been from the insights it has provided into the mechanisms of apoptosis and autoimmunity, but because it is such a rare disease there is little incentive to develop specific therapies. The main burdens of disease faced by ALPS patients are due to the accumulation of lymphoid tissue and the flare-ups of autoimmune disease. © 2006 Elsevier Inc. All rights reserved.