MC5R is a functional candidate for fatness in domestic animals and obesity in humans (Switonski et al., 2013) because it regulates interleukin 6 (IL6) (Jun et al., 2010) and downregulates leptin secretion (Hoggard et al., 2004) respectively resulting in increased fat deposition and increased feed intake. Here, IL6 is linked to obesity due to melanocortin 4 receptor deficiency.