Autoimmune lymphoproliferative syndrome (ALPS) caused by mutations in the genes responsible for the extrinsic apoptotic pathway (FAS, FASLG, CASP10) was the first inherited disease presenting with autoimmunity and lymphoproliferation (autoimmune lymphoproliferative immunodeficiency (ALPID) phenotype) that could be linked to a genetic deficiency [3, 4]. The gene discussed is FAS; the disease is Autoimmunity.