These data suggest that the combined effects of both iNKT cell deficiency (CD1d KO) and dysregulated IFNγ production (Yeti) might be attributed to a decrease in protective Foxp3+CD25+CD4+ Treg cells and an increase in pathogenic Foxp3−CD25+CD4+ T cells during DSS-induced colitis. The gene discussed is CD1D; the disease is colitis.