Autoimmune lymphoproliferative syndrome type 1A (ALPS 1A) generally presents in early childhood, and is characterized by chronic, non-malignant lymphadenopathy, usually with autoimmunity. The underlying cause is a defect in lymphocyte apoptosis, or programmed cell death, leading to persistence of mature T and B cells including the usually rare CD4/CD8-double-negative T (DNT) cell. The formal diagnostic triad for ALPS is elevated DNT cells, hepato/splenomegaly, and defective in vitro lymphocyte apoptosis. Autoimmunity may be present, most often directed against erythrocytes, platelets and neutrophils. In some patients, skin rashes, glomerulonephritis, arthritis, Guillan-Barré syndrome and autoimmune hepatitis may occur. The disorder can vary significantly in severity, even within families. Some individuals have only positive laboratory findings, typically including DNT cells, autoantibodies (such as Coombs positivity), hypergammaglobulinemia (IgG, IgM, IgA), elevated serum IL-10, and elevated serum vitamin B12. ALPS patients and their mutation-bearing relatives have a significantly increased risk for both Hodgkin and non-Hodgkin lymphoma.