CDKN2A and hepatocellular carcinoma: In the past two decades, there has been great progress in the identification of candidate HCC-related genetic and epigenetic risk or disease causal factors such as HLA-DRB, HLA-DQB1, and perhaps other HLA regions, PBX4, PNPLA3, GLUL, and STAT4 from genome-wide association studies (GWAS) [2,3,4,5,6]; genome-wide methylation differential analysis (GWMA) also have identified such examples as Ras association domain family member 1A (RASSF1A), P16, SLC22A20, PNPLA7 as epigenetic factors as well as their interaction [7,8,9,10].