A typical example is that of the fat and obesity-associated (FTO) polymorphisms in the FTO gene (that signifies polygenic obesity) (Ho et al., 2010; Keller et al., 2011; Reitz et al., 2012; Verghese et al., 2013a; Caselli et al., 2015). Here, FTO is linked to obesity due to melanocortin 4 receptor deficiency.