T cell-mediated autoimmunity occurs when checkpoints of peripheral tolerance, including suppression by CD4+CD25+FOXP3+ regulatory T cells (Treg cells), fail to delete or otherwise inactivate self-reactive clonotypes.1 Treg cells can either develop in the thymus or differentiate from peripheral naive T cells stimulated under tolerogenic conditions;2 in either case, the expression of the transcription factor FOXP3 is essential for their development and suppressive function.3–5. Here, FOXP3 is linked to Autoimmunity.