One of the causes of ALPS is defective apoptosis, or said another way, an individual has an abnormality in how well lymphocytes (immune cells) die when they are instructed to do so. It is normal for lymphocytes to disintegrate (e.g., die) when they have done their job. In people with ALPS and in some of their affected relatives, the genetic message for the cells to die is altered: the message is not received and the cells do not die when they should. As a result, people with ALPS develop an enlarged spleen, liver and lymph glands, along with a range of other problems involving white blood cell counts and overactive immune responses (autoimmune disease). Some patients have an increased risk of developing lymphatic cancers (lymphoma).