Genetic abnormalities are commonly observed during HCC formation, such as activated oncogenes12 and inactivated tumor suppressor genes.13 Deletion or mutation of wild-type p53 frequently occurs in HCC, indicating a poorer patient prognosis.14 H101, which is generated by both E1B and E3 gene deletions, is a recombinant human type-5 adenovirus.15 H101 infects tumor cells, ultimately killing them through viral oncolysis.16 The active p53 gene in normal cells prevents the adenovirus from replicating and lysing cells, leading to selective H101 replication in cancer cells, rather than normal cells. The gene discussed is TP53; the disease is hepatocellular carcinoma.