CRHR2 and obesity due to melanocortin 4 receptor deficiency: For example, at the Crhr2 gene, which plays roles in lipid and cholesterol metabolism and has been implicated in obesity [46, 47], BL6 had significant changes on the American diet which were restored to standard-diet levels with GW4064 treatment, while NOD had no change in any diet or treatment group (Fig 5E).