AIF1 and obesity due to melanocortin 4 receptor deficiency: WT mice developed characteristic features of obesity that were not seen in Aif1−/− mice, and CT scanning revealed marked expansion of both subcutaneous and visceral adipose depots in HFD-fed WT mice also not found in HFD-fed Aif1−/− mice, or in mice of either genotype on standard chow diet (CD) (Fig. 1a, b).