FOXP3 and immune dysregulation-polyendocrinopathy-enteropathy-X-linked syndrome: The most prominent example is the IPEX (immuno-dysregulation, polyendocrinopathy, enteropathy, X-linked) syndrome, a disease that develops due to mutations in the FOXP3 gene leading to Treg defects and resulting in lethal multi-organ inflammation and autoimmunity (Bacchetta et al., 2018).