Stratification by assay method revealed the HCC group had significantly higher leptin levels than the CFC group by both “ELISA” (SMD = 2.13, 95% CI (1.27, 2.99), P = 0.000) and “RIA” (SMD = 0.79, 95% CI (0.39, 1.19), P = 0.000). The gene discussed is LEP; the disease is hepatocellular carcinoma.