PYY and obesity due to melanocortin 4 receptor deficiency: Liu et al. reported that the peptide YY (PYY) gene polymorphism (rs2880412) displayed a dual effect on obesity susceptibility: the CC genotype elevated obesity risk, whereas the AA genotype conferred protection through the modulation of lipoprotein metabolism [triglycerides (TG)↑ and low-density lipoprotein cholesterol (LDL-C)↓] (50, 51).