Metabolic by-products characteristic of obesity augment the permeability of the blood-brain barrier and induce a sustained liberation of pro-inflammatory cytokines (e.g., interleukin-6, or IL-6), which ultimately increase the activity of the hypothalamic-pituitary-adrenal (HPA-) axis (Foss and Dyrstad, 2011). The gene discussed is IL6; the disease is obesity due to melanocortin 4 receptor deficiency.