CYP2D6 and hepatocellular carcinoma: Moreover, the CYP2D6*10 mutant homozygote T/T frequency was lower (16.7% vs. 46.7%; P < 0.01) and the heterozygote C/T frequency was significantly higher (46.9% vs. 21.9%; P < 0.01) in HCC groups relative to control subjects, respectively.