One study examined DNA hypermethylation of seven tumor-related genes, including APC, WIF1, RUNX3, DLC1, SFRP1, DKK, and E-cad, in HCC patients, and showed that the hypermethylation status of those seven genes in HCC tissues, as defined by extent of CpG island methylation, differs significantly between male and female patients. This evidence concerns the gene WIF1 and hepatocellular carcinoma.