Utilizing a mouse model homologue of FOXP3 deficiency (scurfy mice), the first rescue experiments using adoptive Treg transfer were successfully performed, paving the way for these cells to be applied in therapy of IPEX patients and other autoimmune diseases with dysfunctional FOXP3 expression [13, 15, 16]. This evidence concerns the gene FOXP3 and immune dysregulation-polyendocrinopathy-enteropathy-X-linked syndrome.