These appear to be due to an excess of suicides, accidental deaths and deaths due to substance abuse within those CD4 strata as these causes accounted for 53% (8/15) of deaths at CD4 >650 cells/mm3, and for 66% (2/3) and 44% (8/18) of deaths in persons with CD4 500-650 and 350-500 cells/mm3 respectively. This evidence concerns the gene CD4 and substance abuse.