Although Bim is required for deletion of autoreactive thymocytes, Bim-deficient mice do not succumb to extensive organ-specific autoimmune disease, which may be due to an increase in T regulatory (Treg) cells [37-40], impaired T cell activation [41] and reduced apoptotic sensitivity of the Bim-deficient target cells (See Section 4). Here, BCL2L11 is linked to autoimmune disease.