UCP2 and obesity due to melanocortin 4 receptor deficiency: As for the functional UCP2 promoter variant -866 GA (rs659366), previous studies have found that it is associated with a reduced prevalence of obesity [17], reduced risk of coronary artery disease [51], reduced [52] or increased [14] risk of T2DM, lower insulin secretion [15,53], reduced insulin sensitivity [54], a decreased [13] or increased [17]UCP2 mRNA level in adipose tissue, higher oxidative stress and risk of coronary heart disease [18], decreased HDL-cholesterol [55], and increased serum triglyceride, total cholesterol and LDL-cholesterol levels [56].