Six studies assessed plasma leptin levels using enzyme-linked immunosorbent assays (ELISAs), and their results suggested that the plasma leptin concentration was higher in individuals with OSA compared to those in controls (WMD=4.45 ng/ml, 95%CI=2.75-6.16, P<0.0001; Table 2). The gene discussed is LEP; the disease is obstructive sleep apnea syndrome.