DNMT1 and obesity due to melanocortin 4 receptor deficiency: The key role of DNA methylation and its maintenance enzyme DNMT1 in metabolic inflammation has been revealed in our recent report demonstrating that hypermethylation at peroxisome proliferator activated receptor γ (Pparγ) promoter by saturated fatty acids and proinflammatory cytokines, levels of which are commonly elevated in obesity, promotes M1 proinflammatory macrophage polarization and inflammation in adipose tissue, resulting in insulin resistance in obesity (10).