In addition, it may be difficult to diagnose ALPS, since a biological and clinical overlap exists with other diseases, which may show lymphoproliferation, autoimmunity, and apoptosis defects, such as caspase-8 deficiency (CEDS), RAS-associated autoimmune leukoproliferative disease (RALD), Dianzani autoimmune lymphoproliferative disease (DALD), and even X-linked lymphoproliferative syndrome (XLP) [84,86,100,101,102,103]. The gene discussed is CASP8; the disease is X-linked lymphoproliferative disease.