Sulkowski et al reported that a greaterincrease in CD4 count was associated with increased risk of severe hepatotoxicity (ALT>200 IU/L) in HIV–hepatitis coinfection.28,29 In studies of HIV mono-infected patients that excluded viral hepatitis, one reportedan increased risk of ALT with lower CD4, while another study reported the opposite findings.20,22. The gene discussed is CD4; the disease is animal viral hepatitis.