This may be due to HIV-induced immunodeficiency enhancing HBV-related hepatotoxicity mediated by immune responses.[27] Depletion of CD4 + T cells, a hallmark of HIV infection,[28] inhibits antigen presentation by liver macrophages (Kupffer cells) and cytokine secretion by lymphocytes, leading to host immunosuppression.[29] The suppression of the host immune response by HIV infection significantly enhances HBV replication,[30] which may in turn leads to severe liver damage. The gene discussed is CD4; the disease is immunodeficiency disease.