Increasing prevalence of obesity is thought to contribute to the increasing incidence of RCC via several hormonal mechanisms including free estrogen [41], insulin and IGF-1 [42, 43], as well as physical damage mechanisms by lipid peroxidation, higher glomerular filtration rate and renal plasma flow [44, 45]. The gene discussed is IGF1; the disease is obesity due to melanocortin 4 receptor deficiency.