We also demonstrated an association between imprinted genes and obesity: In white adipose tissue (WAT), Igf2 and Peg3, paternally expressed imprinted genes (PEGs) involved in the regulation of body fat accumulation, were down-regulated in B6 and (PWK × B6) F1 mice, which are susceptible to high fat diet (HFD)-induced obesity, but not in PWK and (B6 × PWK) F1 mice, which are resistant. Here, PEG3 is linked to obesity due to melanocortin 4 receptor deficiency.