With virtually no detectable levels of fas protein, these mice develop an ALPS-like phenotype that includes autoimmunity, lymphadenopathy, splenomegaly, and expansion of CD4−/CD8− DNTs and have been used historically to evaluate the potential benefit of other therapeutic candidates (11, 12, 13, 14, 15, 16, 17, 18, 19, 20). This evidence concerns the gene FAS and Splenomegaly.