MALT1 and Immunodeficiency: Surprisingly though, congenital disruption of MALT1 protease function resulted in a spontaneous and lethal Immunodeficiency-Polyendrocrinopathy and Enteropathy-X-linked (IPEX)-like multi-organ inflammatory pathology in MALT1 protease-deficient (MALT1 PD) animals, caused by an impaired regulatory T cell (Treg) compartment (13–16).