The area under the curve (AUC) of GPC3 in diagnosing HCC was 0.689 (95% CI: 0.620–0.753, p < 0.0001), and the AUC of AFP in diagnosing HCC was 0.809 (95% CI: 0.748–0.861), higher than that of GPC3 (p = 0.0151). The gene discussed is GPC3; the disease is hepatocellular carcinoma.