Interestingly, although the most common clinical cause of obesity is over-nutrition rather than genetic abnormalities, recent genome-wide association studies have identified single-nucleotide polymorphisms in the Prox-1 that are linked with increased waist circumferences and obesity (Kim et al., 2013; Lecompte et al., 2013). Here, PROX1 is linked to obesity due to melanocortin 4 receptor deficiency.