Several prospective studies have also suggested that breast cancer risk was positively associated with increasing levels of leptin [ORQ4 vs. Q1= 1.94 (1.37–2.75)] and the leptin-to-adiponectin ratio [ORQ4 vs. Q1= 1.91 (1.36–2.68)] [11] while other reported no association with leptin [13, 15, 22, 23]. The gene discussed is LEP; the disease is breast cancer.