Circulating apolipoprotein A1 (P = 0.009), HDL cholesterol (HDL-C) (P < 0.0001), cholesterol efflux (P = 0.002) and paroxonase-1 (PON-1) activity (P < 0.0001) were lower, and serum amyloid A (SAA) (P < 0.0001) was higher in participants with obesity compared to controls. This evidence concerns the gene APOA1 and obesity due to melanocortin 4 receptor deficiency.