In poultry, elevated leptin levels are associated with leptin resistance, a state in which hepatic and peripheral tissues fail to respond to leptin signaling. This impairment disrupts lipid homeostasis by reducing fatty acid oxidation while sustaining lipogenesis. Consequently, excess lipid deposition occurs in the liver, predisposing birds to NAFLD progression. The gene discussed is LEP; the disease is metabolic dysfunction-associated steatotic liver disease.