INS and obesity due to melanocortin 4 receptor deficiency: We observed an increase in serum total cholesterol (Figure 1F), and fasting insulin levels (Figure 1G) in Batf3-/- mice as early as 8 weeks of age, which preceded the development of obesity, and increased fasting blood glucose levels in Batf3-/- mice compared to WT mice at 16 weeks of age (Figure 1H).