Patients with both high serum myostatin and high serum AFP levels had 5-year HCC risks up to 18.0%, a significantly higher risk of HCC development than 1.4%, 5-year HCC risk with both low serum myostatin and low serum AFP levels (HR 14.70, 95% CI 5.72–37.81, p < 0.001). The gene discussed is MSTN; the disease is hepatocellular carcinoma.