For example, the FTO gene encodes for an enzyme that is able to remove methyl groups from DNA [77], long-term exposure to high-fat diet can decrease the melanocortin-4 receptor (MC4R) gene methylation [78] and high-fat diet–induced obesity can modify leptin methylation patterns [79]. The gene discussed is MC4R; the disease is obesity due to melanocortin 4 receptor deficiency.