Autoimmune lymphoproliferative syndrome (ALPS) is a disorder associated with abnormal lymphocyte apoptosis, lymphoproliferation, and autoimmunity. It is inherited as an autosomal dominant pattern with variable penetrance. The mutations in most ALPS patients are in the gene encoding the lymphocyte protein Fas. Some forms of ALPS do not involve FAS gene mutations. Severe lymphadenopathy and splenomegaly are common. Clinically Autoantibodies most often are directed to red blood cells, neutrophils, and platelets. Hemolytic anemia, autoimmune neutropenia, and immune thrombocytopenia purpura occur frequently. ALPS patients have lymphocytosis and a number of lymphocyte abnormalities, including the marked expansion of T lymphocytes that express alpha/beta T-cell receptors but neither CD4 nor CD8 surface markers (TCRalpha/beta+ ; CD4- ; CD8- cells). Lymphoproliferation in ALPS patients is generally benign, but they are at increased risk for the development of Hodgkin's and non-Hodgkin's lymphoma. At present, more than 100 patients have been reported in the literature.
Last update: July 2005