For proper development and function of Treg cells, Tregs are crucially depend on the forkhead box transcription factor FOXP3; loss of Foxp3 function in humans and rodents results in devastating autoimmunity (Jordan et al., 2001; Seddiki et al., 2006; Toker et al., 2013). The gene discussed is FOXP3; the disease is Autoimmunity.