FAS and autoimmune lymphoproliferative syndrome: A condition that has characteristics similar to asplenia is found in Autoimmune lymphoproliferative syndrome (ALPS), a rare hereditary disease, caused by impaired FAS-mediated apoptosis of lymphocytes.119–121 Autoimmune lymphoproliferative syndrome (ALPS) presents in childhood with nonmalignant lymphadenopathy and splenomegaly associated with a characteristic expansion of mature CD4 and CD8 negative or double negative T-cell receptor ab1 T lymphocytes.119–121 Elevated counts of circulating TCRab1 double-negative CD42CD82 T lymphocyte cells (DN-Ts) are hallmarks of the disease.