These observations and the finding that a plethora of MC4R loss-of-function variants predispose to human obesity have made the MC4R an attractive target for the development of novel, anti-obesity pharmacotherapies (Huszar et al, 1997; Yeo et al, 1998; Farooqi et al, 2003). This evidence concerns the gene MC4R and obesity due to melanocortin 4 receptor deficiency.