Obesity can lead to the infiltration of immune cells such as macrophages and lymphocytes, which are important sources of circulating pro-inflammatory factors (tumor necrosis factor-α and interleukin-6); high levels of pro-inflammatory mediators promote cancer development and progression through local and systemic effects [33, 45–47]. The gene discussed is TNF; the disease is obesity due to melanocortin 4 receptor deficiency.