Compared with controls, only the CLH for CYP2E1 in HCC patients was significantly increased (P=1.28E-4), while the CLH values for CYP1A2, 2A6, 2B6, 2C8, 2C19, and 3A4/5 were significantly reduced (P=6.14E-13, 3.86E-6, 1.46E-3, 9.98E-27, 1.87E-9, and 1.30E-2, respectively) and the CLH for CYP2C9 and 2D6 did not significantly change. The gene discussed is CYP1A2; the disease is hepatocellular carcinoma.