Mouse models with severe autoimmune phenotype in addition to the genetic defect of the FOXP3 gene prevent the development of Tregs resulting in impaired activation of the gut immune system [40] and eventually leading to inflammation in the gut. Furthermore, evidence shows that a mutation in the FOXP3 gene contributes to the development of immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome, a rare autoimmune disease, along with other autoimmune conditions such as IBD, diabetes, and arthritis [41]. The gene discussed is FOXP3; the disease is arthritic joint disease.