It has been reported that Jα18−/− mice that lack iNKT cells developed diet-induced obesity to the same extent as WT mice, whereas CD1d−/− mice lacking both iNKT and vNKT cells exhibited improved metabolic parameters as compared with WT mice, suggesting that vNKT cells may also respond to endogenous Ag presented by CD1d on adipocytes18. The gene discussed is CD1D; the disease is obesity due to melanocortin 4 receptor deficiency.