However, while Malt1-KO mice as well as MALT1 CID patients display impaired T cell activation (3, 22, 38–47), this is not the case for IPEX patients, scurfy mice and mice only lacking Malt1 in Tregs, where there is a failure to control T cell activation due to the absence of Tregs or the reduced functionality of Tregs leading to lymphoproliferation and autoimmunity, resulting in death (36, 49, 63, 65–67, 71). This evidence concerns the gene MALT1 and combined immunodeficiency.