LEP and obesity due to melanocortin 4 receptor deficiency: Animal model studies, indeed, have shown that a diet rich in fats and carbohydrates, with a consequent increase in body weight, can be associated with changes in DNA methylation patterns, which affect the promoter region of several genes involved in energetic homeostasis and obesity, such as LEP, NADH dehydrogenase (ubiquinone) 1 β subcomplex subunit 6 (NDUFB6), and FASN.