While the focus to date has been on opportunistic infections that are most frequent at CD4 <200 cells/μL, recent studies have raised concern about the risk of death from liver, renal, and heart diseases, as well as from "non-AIDS" cancers; incidence of these diseases is increased at lower CD4 counts, with significant differences seen between those with CD4 <350 cells/μL and those with CD4 >350 cells/μL [23]. Here, CD4 is linked to AIDS.