The involvement of several genes and multiple molecular/signalling oncogenic pathways (including growth factors, Notch, and pro-inflammatory signalling) events along with LEP gene promoter methylation, protein expression, and the obesity-related metabolic events highlight the magnitude and complexity of LEP molecular functions in both health or disease as discussed earlier (Figure 4) [49,83]. This evidence concerns the gene LEP and obesity due to melanocortin 4 receptor deficiency.