In addition, we found that the biosynthesis pathway for long-chain polyunsaturated fatty acid is up-regulated in the liver of female huCETP transgenic mice, which was associated with the increased liver fatty acid β-oxidation and reduced liver fat content, further supporting the protective role of CETP in lipid and lipoprotein metabolism with obesity. This evidence concerns the gene CETP and obesity due to melanocortin 4 receptor deficiency.