CD4 and autoimmune disease: The functional or quantitative modification of FOXP3 leads to lack of efficient CD4+CD25+Treg cells, resulting in immune dysregulation, polyendocrinopathy, enteropathy, X-linked syndrome (Bennett et al., 2001; Wildin et al., 2002), scurfy mice and other autoimmune diseases including vitiligo supports the importance of Treg cells and FOXP3 in keeping autoreactive T cells in check (Yagi et al., 2004; Lahl et al., 2007).