Significant decrease in expression of CYP1A2, CYP2C8, CYP2C9, CYP2E1 and CYP3A4 was reported by Ren et al. [28] in tumor tissues from patients with hepatocellular carcinoma, what is in line with our result for these genes in Wilson’s disease livers. This evidence concerns the gene CYP3A4 and Wilson disease.