Autoimmune lymphoproliferative syndrome IA (ALPS-FAS) is a disorder in which the body cannot properly regulate the number of immune system cells (lymphocytes). This results in the overproduction of lymphocytes, which build up and cause enlargement of the lymph nodes, liver and spleen. Affected individuals can have a variety of autoimmune disorders, most of which damage the blood cells; some of the autoimmune disorders associated with ALPS can also damage the kidneys, liver, eyes, nerves, or connective tissues. Other signs and symptoms may include skin rashes or inflammation of fat under the skin (panniculitis); joint pain (arthritis); inflammation of blood vessels (vasculitis); mouth sores; premature ovarian failure; and the development of neurological damage. ALPS-FAS is caused by mutations in the FAS gene, and makes up about 75% of all ALPS cases. It is usually inherited in an autosomal dominant manner, meaning that it is passed parent to child, and if one parent has it, there is a 50% chance their child will too. Management may include steroids or other medications, blood transfusions, and/or splenectomy (removal of the spleen) depending on the severity of the disorder.