RXRA and obesity due to melanocortin 4 receptor deficiency: A few human studies investigating the epigenetic changes of early postnatal nutrition showed thatCpG3 methylation of leptin (LEP) and retinoid X receptor alpha (RXRA) obesity-related genes in infants are increased or decreased, depending on the duration of breastfeeding, and as a result, activate the PPAR-induced DNA demethylation in WAT, which drives changes in breast milk fatty acid (BM FA) composition [108].