Activation-induced cytidine deaminase (AID) acts as genomic mutants in activated B cells, and inappropriate expression of AID is associated with immunopathological phenotypes of human B cell malignancies. Abnormal activation of AID in hepatocytes leads to the accumulation of multiple genetic changes in the p53 gene, which may enhance genetic susceptibility to mutagenesis leading to HCC development. Here, AICDA is linked to hepatocellular carcinoma.