Zero tolerance! A perspective on monogenic disorders with defective regulatory T cells and IBD-like disease.

Recently, several studies have investigated a number of rare monogenic autoimmune disorders, in which the causative genetic defects were identified and found to affect the development or function of regulatory T cells (Tregs). The studies of these disorders have facilitated a deeper understanding of the mechanisms involved in immune regulation and tolerance. Furthermore, these studies have highlighted the importance of Tregs in maintaining homeostasis at the mucosal interface between the host and microbiome. Here, we offer our perspective on these monogenic autoimmune disorders, highlighting their overlapping clinical features with inflammatory bowel disease.