PPARG and obesity due to melanocortin 4 receptor deficiency: Thus, an inherited predisposition to obesity (exemplified by the association between dietary fat intake and obesity in carriers of the PPARG2 Pro12Ala allele; Memisoglu et al. 2003) is in principle modifiable by diet (Walters et al. 2010; Ramachandrappa and Farooqi 2011).